Selasa, 09 Juli 2013
Anomalies of eruption in mixed dentition
In the mixed dentition, three other anomalies of eruption are fairly common:
1. Infraoccluded primary teeth usually exfoliate provided that the permanent successors are present, but they should be kept under review. If they are not shed and eruption of the permanent tooth is seriously delayed, or if the infraocclusion becomes very marked, then they should be extracted and a space maintainer fitted if appropriate.
2. Impaction of the upper first permanent molar into the distal of the upper second primary molar causing resorption. It is possible to disimpact the tooth with an appliance, but the problem usually resolves spontaneously when the primary molar is shed. The resorption may cause pain if it involves the pulp, in which case the primary molar should be removed. This allows the permanent molar to move rapidly mesially, and a space maintainer or an active appliance to move it distally should be considered.
3. Second premolars in unfavourable positions are sometimes seen as incidental findings on panoramic radiographs, but fortunately they usually correct spontaneously and eventually erupt satisfactorily. Very occasionally this does not happen, and a few cases have been reported of a lower second premolar migrating towards the mandibular ramus. Upper or lower second premolars that are blocked out of the arch because of crowding usually erupt, but are displaced lingually.
ANOMALIES OF ERUPTION-THE ECTOPIC MAXILLARY CANINE
Introduction
The path of eruption of any tooth can become disturbed. Sometimes the reason is obvious, such as a supernumerary tooth impeding an upper incisor, but often it is obscure. In clinical orthodontics, the most common problem of aberrant eruption is the impacted maxillary canine, which is second only to the third molar in the frequency of impaction.
Prevalence of impacted maxillary canines
Ectopic maxillary canines occur in about 2% of the population, of which about 85% of canines are palatal and 15% buccal to the line of the upper arch. The risk of impaction of the upper canine is greater where the lateral incisor is diminutive or absent¾the lateral incisor root is known to guide the erupting canine. An impacted canine can sometimes resorb adjacent incisor roots, and this risk may be as high as 12%. Incisor resorption is sometimes quite dramatic.
The path of eruption of any tooth can become disturbed. Sometimes the reason is obvious, such as a supernumerary tooth impeding an upper incisor, but often it is obscure. In clinical orthodontics, the most common problem of aberrant eruption is the impacted maxillary canine, which is second only to the third molar in the frequency of impaction.
Prevalence of impacted maxillary canines
Ectopic maxillary canines occur in about 2% of the population, of which about 85% of canines are palatal and 15% buccal to the line of the upper arch. The risk of impaction of the upper canine is greater where the lateral incisor is diminutive or absent¾the lateral incisor root is known to guide the erupting canine. An impacted canine can sometimes resorb adjacent incisor roots, and this risk may be as high as 12%. Incisor resorption is sometimes quite dramatic.
Impacted canine causing root resorption
Clinical assessment
During the mixed dentition stage the normal path of eruption of the maxillary canines is slightly buccal to the line of the arch, and from about 10 years of age the crowns should be palpable as bulges on the buccal aspect of the alveolus.
If not, an abnormal path of eruption should be suspected, particularly where eruption of one canine is very delayed compared with the other side. Unerupted maxillary canines should be palpated routinely on all children from the age of 10 years until eruption.
Radiographic assessment
Where the canine is not palpable it should be assessed radiographically. A periapical radiograph shows whether the primary canine root is resorbing normally and whether the canine follicle is enlarged. If the apex of the primary canine is not resorbing, with either no root resorption or only lateral resorption, the path of eruption of the permanent canine may be abnormal. However, a single radiograph cannot fully determine the unerupted canine's position relative to the other teeth¾two views are needed for this, either at right angles to each other or for the parallax technique.
Parallax technique
This method, also known as the tube-shift method, compares two views of the area taken with the X-ray tube in two different positions. (a) shows a palatal canine on a periapical film being taken with the tube positioned forward or mesially. A second film taken with the tube positioned further distally gives an image which apparently shows the canine crown in a different position relative to the adjacent roots. In this case the image of the canine appears to have shifted distally when compared with the first film, that is in the same direction that the tube was moved, which indicates that the canine is palatal to the other teeth. An apparent shift in the opposite direction to the tube shift would indicate that the tooth is lying buccally to the other teeth.
The parallax technique works best using two periapical views, but with care it can also be applied to a panoramic tomogram with a standard occlusal view, using vertical shift. The tube position is low down for the panoramic tomogram and much higher for the occlusal view, and so in this example the palatal canine appears to be nearer the incisor apices in the occlusal view, i.e. its apparent movement is upwards with the tube. The size of the image of a displaced tooth on a panoramic radiograph is another indicator, being enlarged if it is palatal and reduced if it is labial or buccal. However, a periapical view is still necessary to check for associated pathology, and this can be used with the occlusal view to make another parallax pair. The combination of panoramic, standard occlusal, and periapical views, such as that in, allows comprehensive assessment of a maxillary canine.
Two films at right angles
This method is more applicable to the specialist as it involves a taking lateral skull view and a posteroanterior (p-a) view: possibly a p-a skull, but more commonly using a panoramic radiograph for the same purpose. The lateral skull view shows whether the canine crown is buccal or palatal to the incisor roots, and the p-a or panoramic view shows how close it is to the mid-line. The angulation of the tooth and its vertical position are assessed using both views. An intraoral view must also be taken to check for any associated pathology.
The position of the impacted canine's crown should be determined as being buccal, palatal, or in the line of the arch. The degree of displacement should be assessed horizontally, that is how close it is to the mid-line, in terms of how far it overlaps the roots of the incisors. The canine crown's vertical position is assessed relative to the incisor apices. An estimate should also be made of the tooth's angulation and the position of its apex relative to the line of the arch.
Other radiographic signs that may suggest an abnormal path of eruption are: obvious asymmetry between the positions of the two upper canines; lack of resorption of the root of the primary canine on the affected side; and resorption of permanent incisor roots. If there are signs of incisor resorption, urgent advice and treatment should be sought.
During the mixed dentition stage the normal path of eruption of the maxillary canines is slightly buccal to the line of the arch, and from about 10 years of age the crowns should be palpable as bulges on the buccal aspect of the alveolus.
If not, an abnormal path of eruption should be suspected, particularly where eruption of one canine is very delayed compared with the other side. Unerupted maxillary canines should be palpated routinely on all children from the age of 10 years until eruption.
Radiographic assessment
Where the canine is not palpable it should be assessed radiographically. A periapical radiograph shows whether the primary canine root is resorbing normally and whether the canine follicle is enlarged. If the apex of the primary canine is not resorbing, with either no root resorption or only lateral resorption, the path of eruption of the permanent canine may be abnormal. However, a single radiograph cannot fully determine the unerupted canine's position relative to the other teeth¾two views are needed for this, either at right angles to each other or for the parallax technique.
Parallax technique
This method, also known as the tube-shift method, compares two views of the area taken with the X-ray tube in two different positions. (a) shows a palatal canine on a periapical film being taken with the tube positioned forward or mesially. A second film taken with the tube positioned further distally gives an image which apparently shows the canine crown in a different position relative to the adjacent roots. In this case the image of the canine appears to have shifted distally when compared with the first film, that is in the same direction that the tube was moved, which indicates that the canine is palatal to the other teeth. An apparent shift in the opposite direction to the tube shift would indicate that the tooth is lying buccally to the other teeth.
The parallax technique works best using two periapical views, but with care it can also be applied to a panoramic tomogram with a standard occlusal view, using vertical shift. The tube position is low down for the panoramic tomogram and much higher for the occlusal view, and so in this example the palatal canine appears to be nearer the incisor apices in the occlusal view, i.e. its apparent movement is upwards with the tube. The size of the image of a displaced tooth on a panoramic radiograph is another indicator, being enlarged if it is palatal and reduced if it is labial or buccal. However, a periapical view is still necessary to check for associated pathology, and this can be used with the occlusal view to make another parallax pair. The combination of panoramic, standard occlusal, and periapical views, such as that in, allows comprehensive assessment of a maxillary canine.
Two films at right angles
This method is more applicable to the specialist as it involves a taking lateral skull view and a posteroanterior (p-a) view: possibly a p-a skull, but more commonly using a panoramic radiograph for the same purpose. The lateral skull view shows whether the canine crown is buccal or palatal to the incisor roots, and the p-a or panoramic view shows how close it is to the mid-line. The angulation of the tooth and its vertical position are assessed using both views. An intraoral view must also be taken to check for any associated pathology.
The position of the impacted canine's crown should be determined as being buccal, palatal, or in the line of the arch. The degree of displacement should be assessed horizontally, that is how close it is to the mid-line, in terms of how far it overlaps the roots of the incisors. The canine crown's vertical position is assessed relative to the incisor apices. An estimate should also be made of the tooth's angulation and the position of its apex relative to the line of the arch.
Other radiographic signs that may suggest an abnormal path of eruption are: obvious asymmetry between the positions of the two upper canines; lack of resorption of the root of the primary canine on the affected side; and resorption of permanent incisor roots. If there are signs of incisor resorption, urgent advice and treatment should be sought.
Parallax location of |3. (a) Radiograph taken with the tube positioned forward shows that the image of the canine crown is slightly mesial to the image of |1. (b) Radiograph taken with the tube positioned further distally shows that the image of |3 is further distally. The image of |3 has shifted in the same direction as the tube shift:|3 is therefore nearer to the film than |1, i.e. it is palatal to the line of the arch. (c) Diagrammatic representation of how a palatally positioned tooth moves 'with' the tube from left to right
Early treatment
During the later mixed dentition, if an upper canine is not palpable normally and is found to be ectopic, extraction of the primary canine has a good chance of correcting or improving the path of eruption of the permanent canine, provided it is not too severely displaced. Extraction of the primary canine is only appropriate under these conditions:
(1) early detection¾mixed dentition;
(2) canine crown overlap of no more than half the width of the adjacent incisor root as seen on a panoramic view;
(3) canine crown no higher than the apex of the adjacent incisor root;
(4) angle of 30° or less between the canine's long axis and the mid-sagittal plane;
(5) reasonable space available in the arch¾no more than moderate crowding.
Unless the upper arch is spaced, the contralateral primary canine should also be removed to prevent the upper centreline shifting. Eruption of the permanent canine should be monitored clinically and if necessary radiographically, and specialist advice sought if it fails to show reasonable improvement after a year.
The main disadvantage of extracting the primary canine is losing the option of retaining it if the permanent canine fails to erupt. It may also allow forward drift of the upper buccal teeth where there is a tendency to crowding, and if space is critical a space maintainer should be fitted.
Later treatment
The treatment options in the permanent dentition are to:
(1) expose the canine and align it orthodontically;
(2) transplant the canine;
(3) extract the canine;
(4) leave the impacted canine in situ.
Exposure and orthodontic alignment
This is the treatment of choice for a well-motivated patient, provided the impaction is not too severe. The canine should lie within these limits:
(1) canine crown overlapping no more than half the width of the central incisor root;
(2) canine crown no higher than the apex of the adjacent incisor root;
(3) canine apex in the line of the arch.
The tooth can either be exposed into the mouth and the wound packed open, or a bracket attached to a gold chain can be bonded to it and the wound closed. An orthodontic appliance, usually fixed, then applies traction to bring the tooth into alignment. This treatment can take up to 2 years, depending on the severity of the canine's displacement. Exposure works well for palatally impacted canines, but buccally impacted canines usually have a poor gingival contour following exposure, even when an apically repositioned flap procedure has been used. For this reason some operators prefer to attach a chain to buccally impacted canines and to close the wound, so that the unerupted canine is brought down to erupt through attached, rather than free, gingiva.
Transplantation
The attraction of transplantation is that orthodontic treatment is avoided and yet the canine is brought into function. Two criteria must be met: the canine can be removed intact with a minimum of root handling; and there must be adequate space for the canine in the arch.
The major cause of failure is root resorption, but the incidence of this is reduced if the surgical technique is atraumatic and the transplanted tooth is root- filled with calcium hydroxide shortly after surgery. The success rate for canine transplantation is about 70% survival at 5 years, but many clinicians regard it as being appropriate in only a few cases.
Extraction of the permanent canine
This is appropriate if the position of the canine puts it beyond orthodontic correction, or if the patient does not want appliance treatment. If present, the primary canine can be left in situ, and although the prognosis is unpredictable, a canine with a good root may last for many years. When it is eventually lost a prosthesis will be needed, and provision of this can be difficult if the overbite is deep¾another factor to be taken into account when considering treatment options.
Extraction of the permanent canine may also be considered where the lateral incisor and premolar are in contact, giving a good appearance. In this case it is often expedient to accept the erupted teeth and extract the canine.
Leaving the unerupted canine in situ
During the early teenage years there is a risk of resorption of adjacent incisor roots so that annual radiographic review is necessary, although the risk of root resorption reduces with increasing age. The onset of root resorption can be quite rapid, and for this reason many impacted canines are removed. There may be a case for retaining the canine in the short term in a younger patient, in case they have a change of heart about orthodontic treatment to align the tooth.
Key Points
Ectopic canines
· About 2% of children have ectopic upper canines, of which 85% are palatal.
· Always palpate for upper canines from the age of 10 years until eruption.
· Non-palpable upper canines should be located radiographically or referred for investigation.
· Consider extraction of a primary canine if a permanent canine is mildly displaced.
· Untreated, unerupted permanent canines may resorb incisor roots and should be radiographed annually during the teenage years.
During the later mixed dentition, if an upper canine is not palpable normally and is found to be ectopic, extraction of the primary canine has a good chance of correcting or improving the path of eruption of the permanent canine, provided it is not too severely displaced. Extraction of the primary canine is only appropriate under these conditions:
(1) early detection¾mixed dentition;
(2) canine crown overlap of no more than half the width of the adjacent incisor root as seen on a panoramic view;
(3) canine crown no higher than the apex of the adjacent incisor root;
(4) angle of 30° or less between the canine's long axis and the mid-sagittal plane;
(5) reasonable space available in the arch¾no more than moderate crowding.
Unless the upper arch is spaced, the contralateral primary canine should also be removed to prevent the upper centreline shifting. Eruption of the permanent canine should be monitored clinically and if necessary radiographically, and specialist advice sought if it fails to show reasonable improvement after a year.
The main disadvantage of extracting the primary canine is losing the option of retaining it if the permanent canine fails to erupt. It may also allow forward drift of the upper buccal teeth where there is a tendency to crowding, and if space is critical a space maintainer should be fitted.
Later treatment
The treatment options in the permanent dentition are to:
(1) expose the canine and align it orthodontically;
(2) transplant the canine;
(3) extract the canine;
(4) leave the impacted canine in situ.
Exposure and orthodontic alignment
This is the treatment of choice for a well-motivated patient, provided the impaction is not too severe. The canine should lie within these limits:
(1) canine crown overlapping no more than half the width of the central incisor root;
(2) canine crown no higher than the apex of the adjacent incisor root;
(3) canine apex in the line of the arch.
The tooth can either be exposed into the mouth and the wound packed open, or a bracket attached to a gold chain can be bonded to it and the wound closed. An orthodontic appliance, usually fixed, then applies traction to bring the tooth into alignment. This treatment can take up to 2 years, depending on the severity of the canine's displacement. Exposure works well for palatally impacted canines, but buccally impacted canines usually have a poor gingival contour following exposure, even when an apically repositioned flap procedure has been used. For this reason some operators prefer to attach a chain to buccally impacted canines and to close the wound, so that the unerupted canine is brought down to erupt through attached, rather than free, gingiva.
Transplantation
The attraction of transplantation is that orthodontic treatment is avoided and yet the canine is brought into function. Two criteria must be met: the canine can be removed intact with a minimum of root handling; and there must be adequate space for the canine in the arch.
The major cause of failure is root resorption, but the incidence of this is reduced if the surgical technique is atraumatic and the transplanted tooth is root- filled with calcium hydroxide shortly after surgery. The success rate for canine transplantation is about 70% survival at 5 years, but many clinicians regard it as being appropriate in only a few cases.
Extraction of the permanent canine
This is appropriate if the position of the canine puts it beyond orthodontic correction, or if the patient does not want appliance treatment. If present, the primary canine can be left in situ, and although the prognosis is unpredictable, a canine with a good root may last for many years. When it is eventually lost a prosthesis will be needed, and provision of this can be difficult if the overbite is deep¾another factor to be taken into account when considering treatment options.
Extraction of the permanent canine may also be considered where the lateral incisor and premolar are in contact, giving a good appearance. In this case it is often expedient to accept the erupted teeth and extract the canine.
Leaving the unerupted canine in situ
During the early teenage years there is a risk of resorption of adjacent incisor roots so that annual radiographic review is necessary, although the risk of root resorption reduces with increasing age. The onset of root resorption can be quite rapid, and for this reason many impacted canines are removed. There may be a case for retaining the canine in the short term in a younger patient, in case they have a change of heart about orthodontic treatment to align the tooth.
Key Points
Ectopic canines
· About 2% of children have ectopic upper canines, of which 85% are palatal.
· Always palpate for upper canines from the age of 10 years until eruption.
· Non-palpable upper canines should be located radiographically or referred for investigation.
· Consider extraction of a primary canine if a permanent canine is mildly displaced.
· Untreated, unerupted permanent canines may resorb incisor roots and should be radiographed annually during the teenage years.
Senin, 08 Juli 2013
RUBBER DAM - Benifits for the patient and dentist, technique
Introduction
Most texts that discuss operative treatment for children advocate the use of rubber dam, but it is used very little in practice despite many sound reasons for its adoption. In the United Kingdom less than 2% of dentists use it routinely. It is perceived as a difficult technique that is expensive in time and arduous for the patient.
In fact, once mastered, the technique makes dentalcare for children easier and a higher standard of care can be achieved in less time than would otherwise be required. In addition, it isolates the child from the operative field making treatment less invasive of their personal space.
The benefits can be divided into three main categories as shown below.
Safety
Damage of soft tissues
The risks of operative treatment include damage to the soft tissues of the mouth from rotary and hand instruments and the medicaments used in the provision of endodontic and other care. Rubber dam will go a long way to preventing damage of this type.
Risk of swallowing or inhalation
There is also the risk that these items may be lost in the patient's mouth and swallowed or even inhaled and there are reports in the literature to substantiate this risk.
Risk of cross-infection
In addition, there is considerable risk that the use of high-speed rotary instruments distribute an aerosol of the patients' saliva around the operating room, putting the dentist and staff at risk of infection. Again, a risk that has been substantiated in the literature.
Nitrous oxide sedation
If this is used it is quite likely that mouth breathing by the child will increase the level of the gas in the environment, again putting dentist and staff at risk. The use of rubber dam in this situation will make sure that exhaled gas is routed via the scavenging system attached to the nose piece. Usually less nitrous oxide will be required for a sedative effect, increasing the safety and effectiveness of the procedure.
Benefits to the child
Isolation
One of the reasons that dentaltreatment causes anxiety in patients is that the operative area is very close to and involved with all the most vital functions of the body such as sight, hearing, breathing, and swallowing. When operative treatment is being performed, all these vital functions are put at risk and any sensible child would be concerned. It is useful to discuss these fears with child patients and explain how the risks can be reduced or eliminated.
Glasses should be used to protect the eyes and rubber dam to protect the airways and the oesophagus. By doing this, and provided that good local analgesia has been obtained, the child can feel themselves distanced from the operation. Sometimes it is even helpful to show the child their isolated teeth in a mirror. The view is so different from what they normally see in the mirror that they can divorce themselves from the reality of the situation.
Relaxation
The isolation of the operative area from the child will very often cause the child to become considerably relaxed¾always provided that there is good pain control. It is common for both adult and child patients to fall asleep while undergoing treatment involving the use of rubber dam¾a situation that rarely occurs without. This is a function of the safety perceived by the patient and the relaxed way in which the dentalteam can work with its assistance.
In fact, once mastered, the technique makes dentalcare for children easier and a higher standard of care can be achieved in less time than would otherwise be required. In addition, it isolates the child from the operative field making treatment less invasive of their personal space.
The benefits can be divided into three main categories as shown below.
Safety
Damage of soft tissues
The risks of operative treatment include damage to the soft tissues of the mouth from rotary and hand instruments and the medicaments used in the provision of endodontic and other care. Rubber dam will go a long way to preventing damage of this type.
Risk of swallowing or inhalation
There is also the risk that these items may be lost in the patient's mouth and swallowed or even inhaled and there are reports in the literature to substantiate this risk.
Risk of cross-infection
In addition, there is considerable risk that the use of high-speed rotary instruments distribute an aerosol of the patients' saliva around the operating room, putting the dentist and staff at risk of infection. Again, a risk that has been substantiated in the literature.
Nitrous oxide sedation
If this is used it is quite likely that mouth breathing by the child will increase the level of the gas in the environment, again putting dentist and staff at risk. The use of rubber dam in this situation will make sure that exhaled gas is routed via the scavenging system attached to the nose piece. Usually less nitrous oxide will be required for a sedative effect, increasing the safety and effectiveness of the procedure.
Benefits to the child
Isolation
One of the reasons that dentaltreatment causes anxiety in patients is that the operative area is very close to and involved with all the most vital functions of the body such as sight, hearing, breathing, and swallowing. When operative treatment is being performed, all these vital functions are put at risk and any sensible child would be concerned. It is useful to discuss these fears with child patients and explain how the risks can be reduced or eliminated.
Glasses should be used to protect the eyes and rubber dam to protect the airways and the oesophagus. By doing this, and provided that good local analgesia has been obtained, the child can feel themselves distanced from the operation. Sometimes it is even helpful to show the child their isolated teeth in a mirror. The view is so different from what they normally see in the mirror that they can divorce themselves from the reality of the situation.
Relaxation
The isolation of the operative area from the child will very often cause the child to become considerably relaxed¾always provided that there is good pain control. It is common for both adult and child patients to fall asleep while undergoing treatment involving the use of rubber dam¾a situation that rarely occurs without. This is a function of the safety perceived by the patient and the relaxed way in which the dentalteam can work with its assistance.
Shows rubber dam placed in the a child and with the comfort it provides it is not unusual for children to fall asleep in the dental chair during treatment under rubber dam.
Benefits to the dentist
Reduced stress
As noted above, once rubber dam has been placed the child will be at less risk from the procedures that will be used to restore their teeth. This reduces the effort required by the operator to protect the soft tissues of the mouth and the airways. Treatment can be carried out in a more relaxed and controlled manner, therefore lessening the stress of the procedure on the dental team.
Retraction of tongue and cheeks
Correctly placed rubber dam will gently pull the cheeks and tongue away from the operative area allowing the operator a better view of the area to be treated.
Retraction of gingival tissue
Rubber dam will gently pull the gingival tissues away from the cervical margin of the tooth, making it much easier to see the extent of any caries close to the margin and often bringing the cervical margin of a prepared cavity above the level of the gingival margin thus making restoration considerably easier. Interdentally, this retraction should be assisted by placing a wedge firmly between the adjacent teeth as soon as the dam has been placed. This wedge is placed horizontally below the contact area and above the dam, thus compressing the interdental gingivae against the underlying bone. Approximal cavities can then be prepared, any damage from rotary instruments being inflicted on the wedge rather than the child's gingival tissue.
Quite often it can be difficult and time consuming to take the rubber dam between the contacts because of dentalcaries or broken restorations. It is possible to make life easier by using a 'trough technique', which involves snipping the rubber dam between the punched holes. All the benefits of rubber dam are retained except for the retraction and protection of the gingival tissues.
Moisture control
As mentioned previously, silver amalgam is probably the only restorative material that has any tolerance to being placed in a damp environment, and there is no doubt that it and all other materials will perform much more satisfactorily if placed in a dry field. Rubber dam is the only technique that readily ensures a dry field.
Reduced stress
As noted above, once rubber dam has been placed the child will be at less risk from the procedures that will be used to restore their teeth. This reduces the effort required by the operator to protect the soft tissues of the mouth and the airways. Treatment can be carried out in a more relaxed and controlled manner, therefore lessening the stress of the procedure on the dental team.
Retraction of tongue and cheeks
Correctly placed rubber dam will gently pull the cheeks and tongue away from the operative area allowing the operator a better view of the area to be treated.
Retraction of gingival tissue
Rubber dam will gently pull the gingival tissues away from the cervical margin of the tooth, making it much easier to see the extent of any caries close to the margin and often bringing the cervical margin of a prepared cavity above the level of the gingival margin thus making restoration considerably easier. Interdentally, this retraction should be assisted by placing a wedge firmly between the adjacent teeth as soon as the dam has been placed. This wedge is placed horizontally below the contact area and above the dam, thus compressing the interdental gingivae against the underlying bone. Approximal cavities can then be prepared, any damage from rotary instruments being inflicted on the wedge rather than the child's gingival tissue.
Quite often it can be difficult and time consuming to take the rubber dam between the contacts because of dentalcaries or broken restorations. It is possible to make life easier by using a 'trough technique', which involves snipping the rubber dam between the punched holes. All the benefits of rubber dam are retained except for the retraction and protection of the gingival tissues.
Moisture control
As mentioned previously, silver amalgam is probably the only restorative material that has any tolerance to being placed in a damp environment, and there is no doubt that it and all other materials will perform much more satisfactorily if placed in a dry field. Rubber dam is the only technique that readily ensures a dry field.
'Trough technique' of rubber dam placement.
Technique
Most texts on operative dentistry demonstrate techniques for the use of rubber dam. It is not intended to duplicate this effort, but it would seem useful to point out features of the technique that have made life easier for the authors when using rubber dam with children.
Analgesia
Placement of rubber dam can be uncomfortable especially if a clamp is needed to retain it. Even if a clamp is not required the sharp cut edge of the dam can cause mild pain. Soft tissue analgesia can be obtained using infiltration in the buccal sulcus followed by an interpapillary injection. This will usually give sufficient analgesia to remove any discomfort from the dam. However, more profound analgesia may be required for the particular operative procedure that has to be performed.
Method of application
There are at least four different methods of placing the dam, but most authorities recommend a method whereby the clamp is first placed on the tooth, the dam stretched over the clamp and then over the remaining teeth that are to be isolated. Because of the risk of the patient swallowing or inhaling a dropped or broken clamp before the dam is applied, it is imperative that the clamp be restrained with a piece of floss tied or wrapped around the bow. This adds considerable inconvenience to the technique and the authors favour a simpler method whereby the clamp, dam, and frame are assembled together before application and taken to the tooth in one movement. Because the clamp is always on the outside of the dam relative to the patient there is no need to use floss to secure the clamp.
A 5-inch (about 12.5 cm) square of medium dam is stretched over an Ivory frame and a single hole punched in the middle of the square. This hole is for the tooth on which the clamp is going to be placed and further holes should be punched for any other teeth that need to be isolated. A winged clamp is placed in the first hole and the whole assembly carried to the tooth by the clamp forceps. The tooth that is going to be clamped can be seen through the hole and the clamp applied to it. The dam is then teased off the wings using either the fingers or a hand instrument. It can then be carried forward over the other teeth with the interdental dam being 'knifed' through the contact areas. It may need to be stabilized at the front using either floss, a small piece of rubber dam, a 'Wedjet', or a wooden wedge.
Most texts on operative dentistry demonstrate techniques for the use of rubber dam. It is not intended to duplicate this effort, but it would seem useful to point out features of the technique that have made life easier for the authors when using rubber dam with children.
Analgesia
Placement of rubber dam can be uncomfortable especially if a clamp is needed to retain it. Even if a clamp is not required the sharp cut edge of the dam can cause mild pain. Soft tissue analgesia can be obtained using infiltration in the buccal sulcus followed by an interpapillary injection. This will usually give sufficient analgesia to remove any discomfort from the dam. However, more profound analgesia may be required for the particular operative procedure that has to be performed.
Method of application
There are at least four different methods of placing the dam, but most authorities recommend a method whereby the clamp is first placed on the tooth, the dam stretched over the clamp and then over the remaining teeth that are to be isolated. Because of the risk of the patient swallowing or inhaling a dropped or broken clamp before the dam is applied, it is imperative that the clamp be restrained with a piece of floss tied or wrapped around the bow. This adds considerable inconvenience to the technique and the authors favour a simpler method whereby the clamp, dam, and frame are assembled together before application and taken to the tooth in one movement. Because the clamp is always on the outside of the dam relative to the patient there is no need to use floss to secure the clamp.
A 5-inch (about 12.5 cm) square of medium dam is stretched over an Ivory frame and a single hole punched in the middle of the square. This hole is for the tooth on which the clamp is going to be placed and further holes should be punched for any other teeth that need to be isolated. A winged clamp is placed in the first hole and the whole assembly carried to the tooth by the clamp forceps. The tooth that is going to be clamped can be seen through the hole and the clamp applied to it. The dam is then teased off the wings using either the fingers or a hand instrument. It can then be carried forward over the other teeth with the interdental dam being 'knifed' through the contact areas. It may need to be stabilized at the front using either floss, a small piece of rubber dam, a 'Wedjet', or a wooden wedge.
FISSURE SEALING-Introduction, Definition, Clinical technique, Advantages, Disadvantages
Introduction
Fissure sealants cannot be discussed in isolation from caries diagnosis or treatment of pit and fissure caries. The authors discuss use of these materials both preventively and therapeutically.
Toothbrush bristles cannot access the pit and fissure system because the dimensions of the fissures are too small. As a result micro-organisms remain undisturbed within the fissure system. The tooth is most susceptible to plaque stagnation during eruption, that is, a period of between 12 and 18 months. During this time, children need extra parental help in maintaining their oral hygiene. Lesion formation takes place in the plaque stagnation area at the entrance to the fissure and commences with subsurface demineralization. Demineralized enamel is more porous than sound enamel. The more demineralized and porous the affected enamel, the more it shows up both clinically and on radiographs.
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| Before and after fissure sealing |
Key Point
To detect the earliest white spots the tooth must be dried to render them more obvious.
Once the initial lesion has developed, caries may spread laterally such that a small surface lesion may hide a much greater area of destruction below the surface.
Remineralization of occlusal lesions is much more difficult to achieve. Fissure sealing, 6 monthly 2.26% fluoride varnish application with oral hygiene instruction, and a weekly 0.2% sodium fluoride rinse, have all been found to help stabilize the disease and retard the progress of occlusal caries, but the fissure sealing group exhibited the best effectiveness. Many studies have shown that generally as the caries rates decline, the proportion of caries that affects pits and fissures of molar teeth increases, and also that the caries appears to be concentrated in a smaller cohort of children¾most of the decay occurs in 25% of the child population. This predilection has meant that correct use of fissure sealants should have a maximal effect.
There is no dispute that when correctly applied and monitored, fissure sealants are highly effective at preventing dentalcaries in pits and fissures, but interpretation of the correct application and monitoring requires scrutiny.
To detect the earliest white spots the tooth must be dried to render them more obvious.
Once the initial lesion has developed, caries may spread laterally such that a small surface lesion may hide a much greater area of destruction below the surface.
Remineralization of occlusal lesions is much more difficult to achieve. Fissure sealing, 6 monthly 2.26% fluoride varnish application with oral hygiene instruction, and a weekly 0.2% sodium fluoride rinse, have all been found to help stabilize the disease and retard the progress of occlusal caries, but the fissure sealing group exhibited the best effectiveness. Many studies have shown that generally as the caries rates decline, the proportion of caries that affects pits and fissures of molar teeth increases, and also that the caries appears to be concentrated in a smaller cohort of children¾most of the decay occurs in 25% of the child population. This predilection has meant that correct use of fissure sealants should have a maximal effect.
There is no dispute that when correctly applied and monitored, fissure sealants are highly effective at preventing dentalcaries in pits and fissures, but interpretation of the correct application and monitoring requires scrutiny.
Key Point
Fissure sealants reduce caries incidence but must be carefully monitored and maintained.
Fissure sealants reduce caries incidence but must be carefully monitored and maintained.
Hidden caries ¾ although the occlusal surface looks mostly intact it hides extensive caries.
Caries has been removed. The size of the cavity emphasizes the extent of the lesion.
Who will benefit?
Not every fissure will become carious if it is not sealed. Therefore, each tooth for each child must be assessed on its own merits. The clinician must assess the risk factors for that tooth developing pit or fissure caries. As a general guide to who will benefit, review the British Society for Paediatric Dentistry Policy Document (Nunn et al., 2000).
The main beneficiaries are:
1. Children and young people with medical, intellectual, physical, and sensory impairments, such that their general health would be jeopardized by either the development of oral disease or the need for dentaltreatment. In such children all susceptible sites in both the primary and permanent dentitions should receive consideration.
2. All susceptible sites on permanent teeth should be sealed in children and young people with caries in their primary teeth (dmfs = 2 or more).
3. Where occlusal caries affects one permanent molar, the operator should seal the occlusal surfaces of all the other molars.
4. If the anatomy of the tooth is such that surfaces are deeply fissured, then these should be sealed.
5. Where potential risk factors, such as dietary factors or oral hygiene factors, indicate a high risk of caries, then all sites at risk should be sealed.
6. Where there is a doubt about the caries status of a fissure or it is known to have caries confined to the enamel, fissure sealants may be used therapeutically. After application, it is essential to monitor the surface both clinically and radiologically.
Sealant use must be based on personal, tooth, and surface risk, and the clinician must assess these risks since it might change at any time in the life of the patient. So whereas it was traditionally stated that dentists should complete sealant application up to a year or two after eruption, he or she should assess the potential risk factors regularly, and place the sealant, when indicated irrespective of age. Failure rates are higher when sealants are placed on newly erupted teeth and in mouths with higher previous caries experience. Monitoring the integrity of sealant is vital in those circumstances and any deficiencies in a sealant should be corrected.
Not every fissure will become carious if it is not sealed. Therefore, each tooth for each child must be assessed on its own merits. The clinician must assess the risk factors for that tooth developing pit or fissure caries. As a general guide to who will benefit, review the British Society for Paediatric Dentistry Policy Document (Nunn et al., 2000).
The main beneficiaries are:
1. Children and young people with medical, intellectual, physical, and sensory impairments, such that their general health would be jeopardized by either the development of oral disease or the need for dentaltreatment. In such children all susceptible sites in both the primary and permanent dentitions should receive consideration.
2. All susceptible sites on permanent teeth should be sealed in children and young people with caries in their primary teeth (dmfs = 2 or more).
3. Where occlusal caries affects one permanent molar, the operator should seal the occlusal surfaces of all the other molars.
4. If the anatomy of the tooth is such that surfaces are deeply fissured, then these should be sealed.
5. Where potential risk factors, such as dietary factors or oral hygiene factors, indicate a high risk of caries, then all sites at risk should be sealed.
6. Where there is a doubt about the caries status of a fissure or it is known to have caries confined to the enamel, fissure sealants may be used therapeutically. After application, it is essential to monitor the surface both clinically and radiologically.
Sealant use must be based on personal, tooth, and surface risk, and the clinician must assess these risks since it might change at any time in the life of the patient. So whereas it was traditionally stated that dentists should complete sealant application up to a year or two after eruption, he or she should assess the potential risk factors regularly, and place the sealant, when indicated irrespective of age. Failure rates are higher when sealants are placed on newly erupted teeth and in mouths with higher previous caries experience. Monitoring the integrity of sealant is vital in those circumstances and any deficiencies in a sealant should be corrected.
Fig. 9.6 This tooth which is too early to seal with resin, should be painted with fluoride varnish or if the caries risk is very high should be sealed with glass ionomer until further eruption has taken place.
Fig. 9.7 This molar is just at the correct stage to apply fissure sealant. The very small operculum of gingival tissue can be held away from the tooth gently with a flat plastic.
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| Fissure sealing technique |
Clinical technique
Pretreatment prior to sealant application
Tooth preparation with pumice and a rotary brush results in a good clinical retention rate. Dry brushing achieves similar results. Air polishing, using a 'Prophy-Jet', an early air abrasion system that uses sodium bicarbonate particles as the abrasive medium, provides good bond strength and sealant penetration but has not received general acceptance, probably, because most dental surgeries do not possess this equipment.
Some researchers have advocated the use of 'Enameloplasty', a more aggressive intervention into the tooth, that is, mechanical enlargement of the fissures with a bur or with air abrasion, to improve sealant penetration and reduce micro-leakage. Although some studies have confirmed these claims, the authors feel that this is an unnecessary extra procedure to subject the child to, and do not recommend it.
Etching
All the methods of cleaning the tooth, discussed above, should be accompanied with etching of the enamel surface. Etching for just 20 s with a range of concentrations of acid but most often, 35-37.5% phosphoric acid is the tried and tested method. Its one drawback is the susceptibility of the etched surface to saliva or moisture contamination, which reduces the bond strength. Salivary contamination results in significantly reduced bond strengths unless removed by thorough washing. Re-etching of the surface is usually necessary if salivary contamination has occurred.
Bonding agents
Bonding agents used as an additional layer under a resin sealant yield bond strengths significantly greater than the bond strength obtained when using sealant alone. Initial results of clinical trials also show increased retention of the sealant when an intermediate bond is used. New bonding techniques are proving to be less technique sensitive, with respect to moisture control than erstwhile procedures.
The use of a bonding agent under a sealant on wet contaminated surfaces yields bond strengths equivalent to the bond strength obtained when sealant is bonded directly to clean etched enamel without contamination. Most of the data on the subject of using a bonding agent as part of the sealant procedure supports its use. Use of a bonding agent would tend to increase the time and cost of the sealant application but in cases where maintaining a dry surface is difficult or where there are areas of hypomineralization on the surface, it would have many advantages.
Logically, combination of these technologies to achieve better penetration with less steps in the application sequence would be beneficial and there is some evidence already in the use of self-etching primer-adhesive systems. As yet, there has only been a 2-year follow-up but the early results are promising in relation to retention. Other studies have shown that there are concerns about micro-leakage compared with conventional acid etching. The big bonus of the self-etching primer-adhesive system is the speed with which the operator can apply it. In the application procedure for the Prompt-L-Pop system, the operator brushes the self-etching adhesive on to the surface; air thins it, and follows this by immediate placement of the sealant and polymerization. In the study, the average time operators took for the procedure was 1.8 min compared with 3.1 min for conventional technique. Such time saving is very useful in young fidgety children. At present, therefore, there are conflicting views on these systems but with technology moving ever onwards it does seem likely that in the future it should be possible to achieve good etching and bonding with a simpler application method.
Most clinicians will employ a resin-based sealant, because they have a good track record. Many clinical trials have demonstrated the effectiveness of resin sealants and there are several long-term studies, which show the benefits. Fifteen years after a single application, resin sealants have shown 28% complete retention of sealants and 35% partial retention on first permanent molars. Where researchers re-applied sealant to those surfaces that had deficient sealant as determined by yearly exams, 65% complete retention was obtained and only 13% of the surfaces had caries or restorations after 20 years.
Retreatment
Sealants placed in the first permanent molars in children of ages 6, 7, and 8 and in second permanent molars in children of ages 11 and 12 required more re-application than those placed in older teeth. If the clinician places fissure sealant in newly erupted teeth it is more likely to fail, but should still be placed as early as possible, because the teeth are more vulnerable to caries at this time.
Modifying the resin to incorporate fluoride is a logical rationale. However, fluoride release occurs only for a very short time and at a very low level. Many studies over 2-3-year periods have reported good retention but with a similar caries incidence to conventional sealant. Since the addition of fluoride to sealant resin does not have any detrimental effect it could certainly be used, but until the chemistry can be adapted to readily unlock the fluoride, the anti-cariogenicity cannot be attributed to the fluoride.
Greater release of fluoride can be achieved using glass ionomer (poly-alkenoate). Such cements have high levels of fluoride available for release but they suffer from the drawback of poor retention. Even with the very poor retention rates, sealing with glass ionomer does seem to infer some caries protective effect. This may be due to both the fluoride released by the glass ionomer and residual material retained in the bottom of the fissure, invisible to the naked eye.
Hence, glass ionomers, used as sealants can be classed as a fissure sealant but more realistically as a fluoride depot material. They can be usefully employed to seal partially erupted molars in high risk children since eruption of the molars takes 12-18 months and during this time they are often very difficult to clean. Once the teeth are sufficiently erupted the operator may place a resin sealant. They are also useful in children where there are difficulties with the level of co-operation, as the technique does not depend on absolute moisture control.
Logically, improvement in glass ionomer technology has occurred and both resin-modified glass ionomers (RMGI) and compomers have been used as sealants. As yet, studies of these materials used as fissure sealants while available, show no improvement over resin-based sealants and so there is nothing to recommend them in preference to resins.
Filled or unfilled resins?
Retention is better for unfilled resins probably because it penetrates into the fissures more completely. It also does not need occlusal adjustment as it abrades very rapidly. If a filled resin is not adjusted there is a perceptible occlusal change, possible discomfort, and wear of the opposing antagonist tooth.
Coloured or clear material?
Opaque sealants have the advantage of high visibility at recall. It has been found that identification error for opaque resin was only 1% while for clear resin the corresponding figure was 23% with the most common error being false identification of the presence of clear resin on an untreated tooth. The disadvantage of opaque sealant is that the dentist cannot examine the fissure visually at future recalls. The choice of an opaque versus a clear sealant is usually one of personal choice.
Safety issues
There has only been one report of an allergy to the resin used for pit and fissure sealing and concern has been raised about the oestrogenicity of resin-based composites. The proposed culprit, bis-phenol A (BPA), is not a direct ingredient of fissure sealants, but is a chemical that appears in the final product when the raw materials fail to fully react. The amount released orally is undetectable in the systemic circulation and concerns about potential oestrogenicity are probably unfounded.
Sealant bulk in relation to application
It is important to remember that the sealant must be kept to a minimum, consistent with the coverage of the complete fissure system including buccal and lingual pits. Overfilling can lead to reduction in retention and increased micro-leakage.
Sealant monitoring
Once the sealant has been placed the operator must monitor it at recall appointments and repair or replenish as necessary. Teeth lose is between 5% and 10% of sealant volume per year. Partial loss of resin sealant allows ingress of bacteria into the fissure system. This leaves that surface equally at risk from caries compared to an unsealed surface.
Cost-effectiveness
Cost-effectiveness will depend on the caries rate for the children in the population. Where there is a higher caries rate, generalized sealing will protect more surfaces that would have become carious in the future. However, if the caries rate is very high, then the risk of developing interproximal lesions is also higher and may lead to a two surface restoration even when the fissure sealed surfaces remain caries free. In low caries areas, the cost-effectiveness of sealant application en masse is questionable and the dentist should assess each child's individual risk factors. In contrast to this general concept, one study has shown that it is 1.6 times as costly to restore the carious lesions in the first permanent molars in an unsealed group of 5-10-year-old children living in a fluoridated area than it is to prevent them with a single application of pit and fissure sealant. This study also revealed a greater number of lesions if sealant was not utilized.
Sealing over caries
Once caries has been diagnosed it is important to determine its extent. If there is clear unequivocal evidence that the lesion does not extend beyond the enamel, then the surface may be sealed and monitored both clinically and radiologically. If the lesion extends into the dentine, the dentist would normally place either a preventive resin restoration (PRR), or if in an area of occlusal load, a conventional restoration. However, several authors have shown that dentinal carious lesions do not progress under intact sealants. Nevertheless, if the sealant were to fail immediately or shortly after application, then the lesion would have 4-6 months to progress before the next review. We do not advocate sealing over caries except in very exceptional circumstances, that is, very nervous children who cannot cope with even minimal intervention dentistry.
Pretreatment prior to sealant application
Tooth preparation with pumice and a rotary brush results in a good clinical retention rate. Dry brushing achieves similar results. Air polishing, using a 'Prophy-Jet', an early air abrasion system that uses sodium bicarbonate particles as the abrasive medium, provides good bond strength and sealant penetration but has not received general acceptance, probably, because most dental surgeries do not possess this equipment.
Some researchers have advocated the use of 'Enameloplasty', a more aggressive intervention into the tooth, that is, mechanical enlargement of the fissures with a bur or with air abrasion, to improve sealant penetration and reduce micro-leakage. Although some studies have confirmed these claims, the authors feel that this is an unnecessary extra procedure to subject the child to, and do not recommend it.
Etching
All the methods of cleaning the tooth, discussed above, should be accompanied with etching of the enamel surface. Etching for just 20 s with a range of concentrations of acid but most often, 35-37.5% phosphoric acid is the tried and tested method. Its one drawback is the susceptibility of the etched surface to saliva or moisture contamination, which reduces the bond strength. Salivary contamination results in significantly reduced bond strengths unless removed by thorough washing. Re-etching of the surface is usually necessary if salivary contamination has occurred.
Bonding agents
Bonding agents used as an additional layer under a resin sealant yield bond strengths significantly greater than the bond strength obtained when using sealant alone. Initial results of clinical trials also show increased retention of the sealant when an intermediate bond is used. New bonding techniques are proving to be less technique sensitive, with respect to moisture control than erstwhile procedures.
The use of a bonding agent under a sealant on wet contaminated surfaces yields bond strengths equivalent to the bond strength obtained when sealant is bonded directly to clean etched enamel without contamination. Most of the data on the subject of using a bonding agent as part of the sealant procedure supports its use. Use of a bonding agent would tend to increase the time and cost of the sealant application but in cases where maintaining a dry surface is difficult or where there are areas of hypomineralization on the surface, it would have many advantages.
Logically, combination of these technologies to achieve better penetration with less steps in the application sequence would be beneficial and there is some evidence already in the use of self-etching primer-adhesive systems. As yet, there has only been a 2-year follow-up but the early results are promising in relation to retention. Other studies have shown that there are concerns about micro-leakage compared with conventional acid etching. The big bonus of the self-etching primer-adhesive system is the speed with which the operator can apply it. In the application procedure for the Prompt-L-Pop system, the operator brushes the self-etching adhesive on to the surface; air thins it, and follows this by immediate placement of the sealant and polymerization. In the study, the average time operators took for the procedure was 1.8 min compared with 3.1 min for conventional technique. Such time saving is very useful in young fidgety children. At present, therefore, there are conflicting views on these systems but with technology moving ever onwards it does seem likely that in the future it should be possible to achieve good etching and bonding with a simpler application method.
Most clinicians will employ a resin-based sealant, because they have a good track record. Many clinical trials have demonstrated the effectiveness of resin sealants and there are several long-term studies, which show the benefits. Fifteen years after a single application, resin sealants have shown 28% complete retention of sealants and 35% partial retention on first permanent molars. Where researchers re-applied sealant to those surfaces that had deficient sealant as determined by yearly exams, 65% complete retention was obtained and only 13% of the surfaces had caries or restorations after 20 years.
Retreatment
Sealants placed in the first permanent molars in children of ages 6, 7, and 8 and in second permanent molars in children of ages 11 and 12 required more re-application than those placed in older teeth. If the clinician places fissure sealant in newly erupted teeth it is more likely to fail, but should still be placed as early as possible, because the teeth are more vulnerable to caries at this time.
Modifying the resin to incorporate fluoride is a logical rationale. However, fluoride release occurs only for a very short time and at a very low level. Many studies over 2-3-year periods have reported good retention but with a similar caries incidence to conventional sealant. Since the addition of fluoride to sealant resin does not have any detrimental effect it could certainly be used, but until the chemistry can be adapted to readily unlock the fluoride, the anti-cariogenicity cannot be attributed to the fluoride.
Greater release of fluoride can be achieved using glass ionomer (poly-alkenoate). Such cements have high levels of fluoride available for release but they suffer from the drawback of poor retention. Even with the very poor retention rates, sealing with glass ionomer does seem to infer some caries protective effect. This may be due to both the fluoride released by the glass ionomer and residual material retained in the bottom of the fissure, invisible to the naked eye.
Hence, glass ionomers, used as sealants can be classed as a fissure sealant but more realistically as a fluoride depot material. They can be usefully employed to seal partially erupted molars in high risk children since eruption of the molars takes 12-18 months and during this time they are often very difficult to clean. Once the teeth are sufficiently erupted the operator may place a resin sealant. They are also useful in children where there are difficulties with the level of co-operation, as the technique does not depend on absolute moisture control.
Logically, improvement in glass ionomer technology has occurred and both resin-modified glass ionomers (RMGI) and compomers have been used as sealants. As yet, studies of these materials used as fissure sealants while available, show no improvement over resin-based sealants and so there is nothing to recommend them in preference to resins.
Filled or unfilled resins?
Retention is better for unfilled resins probably because it penetrates into the fissures more completely. It also does not need occlusal adjustment as it abrades very rapidly. If a filled resin is not adjusted there is a perceptible occlusal change, possible discomfort, and wear of the opposing antagonist tooth.
Coloured or clear material?
Opaque sealants have the advantage of high visibility at recall. It has been found that identification error for opaque resin was only 1% while for clear resin the corresponding figure was 23% with the most common error being false identification of the presence of clear resin on an untreated tooth. The disadvantage of opaque sealant is that the dentist cannot examine the fissure visually at future recalls. The choice of an opaque versus a clear sealant is usually one of personal choice.
Safety issues
There has only been one report of an allergy to the resin used for pit and fissure sealing and concern has been raised about the oestrogenicity of resin-based composites. The proposed culprit, bis-phenol A (BPA), is not a direct ingredient of fissure sealants, but is a chemical that appears in the final product when the raw materials fail to fully react. The amount released orally is undetectable in the systemic circulation and concerns about potential oestrogenicity are probably unfounded.
Sealant bulk in relation to application
It is important to remember that the sealant must be kept to a minimum, consistent with the coverage of the complete fissure system including buccal and lingual pits. Overfilling can lead to reduction in retention and increased micro-leakage.
Sealant monitoring
Once the sealant has been placed the operator must monitor it at recall appointments and repair or replenish as necessary. Teeth lose is between 5% and 10% of sealant volume per year. Partial loss of resin sealant allows ingress of bacteria into the fissure system. This leaves that surface equally at risk from caries compared to an unsealed surface.
Cost-effectiveness
Cost-effectiveness will depend on the caries rate for the children in the population. Where there is a higher caries rate, generalized sealing will protect more surfaces that would have become carious in the future. However, if the caries rate is very high, then the risk of developing interproximal lesions is also higher and may lead to a two surface restoration even when the fissure sealed surfaces remain caries free. In low caries areas, the cost-effectiveness of sealant application en masse is questionable and the dentist should assess each child's individual risk factors. In contrast to this general concept, one study has shown that it is 1.6 times as costly to restore the carious lesions in the first permanent molars in an unsealed group of 5-10-year-old children living in a fluoridated area than it is to prevent them with a single application of pit and fissure sealant. This study also revealed a greater number of lesions if sealant was not utilized.
Sealing over caries
Once caries has been diagnosed it is important to determine its extent. If there is clear unequivocal evidence that the lesion does not extend beyond the enamel, then the surface may be sealed and monitored both clinically and radiologically. If the lesion extends into the dentine, the dentist would normally place either a preventive resin restoration (PRR), or if in an area of occlusal load, a conventional restoration. However, several authors have shown that dentinal carious lesions do not progress under intact sealants. Nevertheless, if the sealant were to fail immediately or shortly after application, then the lesion would have 4-6 months to progress before the next review. We do not advocate sealing over caries except in very exceptional circumstances, that is, very nervous children who cannot cope with even minimal intervention dentistry.
White fissure sealants can easily be check at recall, they are also visible to show the patient and parent to help them understand the procedure.
Clear fissure sealant is less easy to see though its presence can be checked, if an area is giving cause for concern, by etching.
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