Senin, 14 November 2011

White Lesions of Oral Mucosa

White lesions of the oral mucosa are a multifactorial group of disorders,the color of which is produced by the scattering of the light through an altered epithelial surface. The diagnosis and differential diagnosis of oral white lesions should be made on the basis of the medical history, clinical features, and laboratory tests.
 
O Leukoplakia
O Hairy leukoplakia
O Lichen planus
O Lichenoid reactions
O Linea alba
O Nicotinic stomatitis
O Uremic stomatitis
O Cinnamon contact stomatitis
O Chemical burn
O Candidiasis
O Chronic biting
O Geographic tongue
O Hairy tongue
O Furred tongue
O Materia alba of the gingiva
O Fordyce’s granules
O Leukoedema
O White sponge nevus
O Dyskeratosis congenita
O Pachyonychia congenita
O Focal palmoplantar and oral mucosa hyperkeratosis syndrome
O Papilloma
O Verrucous carcinoma
O Squamous-cell carcinoma
O Skin and mucosal grafts
O Epithelial peeling

White Lesions


Leukoplakia

Definition Leukoplakia is a clinical term, and the lesion is defined as a white patch or plaque, firmly attached to the oral mucosa, that cannot be classified as any other disease entity. It is a precancerous lesion.

Etiology The exact etiology remains unknown. Tobacco, alcohol, chronic local friction, and Candida albicans are important predisposing factors. Human papilloma virus (HPV) may also be involved in the pathogenesis of oral leukoplakia.

Clinical features Three clinical varieties (Figs. 1 and 2) are recognized: homogeneous (common), speckled (less common), and verrucous (rare). Speckled and verrucous leukoplakia have a greater risk for malignant transformation than the homogeneous form. The average percentage of malignant transformation for leukoplakia varies between 4% and 6%. The buccal mucosa, tongue, floor of the mouth, gingiva, and lower lip are the most commonly affected sites.

Laboratory tests Histopathological examination.
Differential diagnosis Lichen planus, cinnamon contact stomatitis, candidiasis, hairy leukoplakia, lichen planus reactions, chronic biting, tobacco pouch keratosis, leukoedema, chemical burn, uremic stomatitis, skin graft, some genodermatoses and discoid lupus erythematosus.

Treatment Elimination or discontinuation of predisposing factors, systemic retinoid compounds. Surgical excision is the treatment of choice.
Homogeneous leukoplakia.

Speckled leukoplakia


Hairy Leukoplakia

Definition Hairy leukoplakia is one of the most common and characteristic lesions of human immunodeficiency virus (HIV) infection. Rarely, it can also appear in immunosuppressed patients after organ transplantation.

Etiology Epstein–Barr virus seems to play an important role in the pathogenesis.

Clinical features Hairy leukoplakia presents as a white asymptomatic, often elevated and unremovable patch. The lesion is almost always found bilaterally on the lateral margins of the tongue, and may spread to the dorsumand the ventral surface. Characteristically, the surface of the lesion is corrugated with a vertical orientation. However, smooth and flat lesions may also be seen. The lesion is not precancerous.
Laboratory tests Histological examination, in situ hybridization, polymerase chain reaction (PCR) and electron microscopy.

Differential diagnosis Chronic biting, lichen planus, frictional keratosis, cinnamon contact stomatitis, uremic stomatitis, candidiasis.

Treatment Not required; however, in some cases aciclovir or valaciclovir can be used with success.
Hairy leukoplakia.


Lichen Planus

Definition Lichen planus is a relatively common chronic inflammatory disease of the oral mucosa and skin.

Etiology Although the cause is not well known, T cell-mediated autoimmune phenomena are involved in the pathogenesis of lichen planus.

Clinical features White papules that usually coalesce, forming a network of lines (Wickman’s striae), are the characteristic oral lesions of the disease. Six forms of the disease are recognized in the oral mucosa, classified according to frequency: the common ;the less common ; and the rare . Middle-aged individuals are more com-monly affected (the ratio of women to men ratio is 3 : 2). The buccal mucosa, tongue, and gingiva are the sites of predilection. The skin lesions characteristically appear as polygonal purple, pruritic papules, usually affecting the flexor surfaces of the extremities. The glans penis and nails may also be affected. The disease can usually be diagnosed on clinical grounds alone. The prognosis of lichen planus is usually good, and malignant transformation (particularly of the erosive form) remains controversial.

Laboratory tests Histopathological examination is very helpful. Direct immunofluorescence can also be used, although the features are not specific.

Differential diagnosis Discoid lupus erythematosus, candidiasis, graft-versus-host disease, geographic tongue, leukoplakia, erythroplakia, cicatricial pemphigoid, pemphigus, bullous pemphigoid.

Treatment No treatment is needed in asymptomatic lesions. Topical steroids (ointment in Orabase, intralesional injection), may be helpful. Systemic steroids in low doses can be used in severe and extensive cases. The topical use of antiseptic mouthwashes should be avoided.
Lichen planus of the buccal mucosa: reticular form.

Lichen planus of the dorsum of the tongue: hypertrophic form.

Lichen planus, papular and reticular forms, of the buccal mucosa

Lichen planus, pigmented form, of the buccal mucosa

Lichenoid Reactions

Definition Lichenoid or lichen planus reactions are a heterogeneous group of lesions of the oral mucosa that show clinical and histopathological similarities to lichen planus, but have a different course.

Etiology Hypersensitivity to dental restorative materials, amalgam, composite resins and dental plaque accumulation are the most common causative factors. Rarely, a reaction to drugs may be responsible.

Clinical features Clinically, they appear as white and/or erythematous lesions, usually associated with peripheral delicate white striae.
Erosions are also common . The lesions mimic erosive lichen planus. Characteristically, the lesions are strictly confined to the mucosa directly in contact with the restorative materials, and do not migrate to other sites. The lesions disappear after removal of the adjacent material.

The diagnosis is usually made clinically.

Laboratory tests A skin punch test may be helpful in some cases.

Differential diagnosis Lichen planus, fixed drug eruption, discoid lupus erythematosus, cicatricial pemphigoid, cinnamon contact stomatitis.
Treatment Replacement of the restorative material, polishing and smoothing, and good oral hygiene are recommended. Topical steroid treatment for a short time is also helpful.

Lichanoid drug reaction to allopurinol: white hyperkeratotic lesions and superficial
erosions on the sides of the tongue.

Lichenoid reaction to dental amalgam and cold: white and erythematous
lesions on the buccal mucosa

Linea Alba

Definition Linea alba is a relatively common alteration of the buccal mucosa.
Etiology Pressure, sucking fromthe buccal surface of the teeth.

Clinical features It presents as an asymptomatic, bilateral, linear elevation with a slightly whitish color at the level of the occlusal line of the teeth. It has a normal consistency on palpation. The diagnosis is based on clinical grounds alone.

Treatment No treatment is required.
Linea alba.

Nicotinic Stomatitis

Definition Nicotinic stomatitis, or smoker’s palate, is a common tobacco- related type of keratosis that occurs exclusively on the hard palate, and is classically associated with heavy pipe and cigar smoking.

Etiology The elevated temperature, rather than the tobacco chemicals, is responsible for this lesion.

Clinical features Clinically, the palatal mucosa initially responds to the high temperature with redness. Later, it becomes wrinkled and takes on a diffusely grayish-white color, with numerous micronodules with characteristic punctate red centers, which represent the inflamed and dilated orifices of the minor salivary gland ducts. The lesions are not premalignant, in contrast to the “reverse smoker’s palate” lesion, which is associated with reverse smoking.

Laboratory tests Usually not required. However, a histopathological examination is useful.

Differential diagnosis Reverse smoker’s palate, leukoplakia, discoid lupus erythematosus, candidiasis, lichen planus.

Treatment Cessation of smoking.

Nicotinic Stomatitis

Uremic Stomatitis

Definition Uremic stomatitis is a rare disorder that may occur in patients with acute or chronic renal failure.

Etiology Increased concentration of urea and its products in the blood and saliva. The pathogenesis of oral lesions is not clear. It usually appears when blood concentration of urea exceeds 30 mmol/1. The degradation of oral urea by the enzyme urease forms free ammonia, which may damage the oral mucosa.

Clinical features Four forms of uremic stomatitis are recognized: (a) the ulcerative form, (b) the hemorrhagic form, (c) the nonulcerative, pseudomembranous form, and (d) the hyperkeratotic form. The last two forms appear as white lesions. The nonulcerative, pseudomembranous form presents as painful diffuse erythema covered by a thick whitish-gray pseudomembrane. The hyperkeratotic formpresents asmultiple painful white hyperkeratotic lesions with thin projections. The tongue, and the floor of the mouth are more frequently affected. Xerostomia, uriniferous breath odor, unpleasant taste, and a burning sensation are common symptoms. Candidiasis and viral and bacterial infections are common oral complications. The diagnosis is based on the history, the clinical features, urinalysis and blood urea level determination.

Differential diagnosis Candidiasis, cinnamon contact stomatitis, hairy leukoplakia, white sponge nevus, drug reactions.

Treatment The oral lesions usually improve after hemodialysis. A high level of oral hygiene, mouthwashes with oxygen release agents, and artificial saliva are suggested. Antimycotic, antiviral, and antimicrobial agents if necessary.
Uremic stomatitis, white hyperkeratotic lesions mimic hairy leukoplakia on
the lateral border of the tongue

Uremic stomatitis, whitish-gray pseudomembranes on the tongue and floor
of the mouth.


Cinnamon Contact Stomatitis

Definition Cinnamon contact stomatitis is a relatively common oral mucosal reaction to continuous contact of substances with cinnamon.

Etiology Artificial cinnamon flavoring especially in the form of chewing gum, candies, toothpaste, drops, etc.

Clinical features The condition is characterized by erythema of the oral mucosa, usually in association with desquamation and erosions. White hyperkeratotic plaques are very common. A burning sensation and pain are common symptoms. The lateral borders of the tongue, the buccal mucosa, and the gingiva are more frequently affected. Exfoliative cheilitis and perioral dermatitis may occur. The diagnosis is based on the history and the clinical features.

Differential diagnosis Amalgam contact stomatitis, chronic biting, leukoedema, epithelial peeling, hairy leukoplakia, leukoplakia, candidiasis, uremic stomatitis, lichen planus, discoid lupus erythematosus.

Treatment Discontinuation of any cinnamon product improves the signs and symptoms in approximately two weeks. In severe and extended lesions with erosions, low doses of steroids (e.g., 10 mg/day prednisolone) for one week help the lesions to heal.
Cinnamon Contact Stomatitis

Cinnamon Contact Stomatitis


Chemical Burn

Definition This is an injury to the oral mucosa caused by topical application of caustic agents.

Etiology Causative agents include aspirin, hydrogen peroxide, phenol, alcohol, sodiumperb orate, silver nitrate, trichloroacetic acid, acid etching liquid, and varnishes of tooth cavities.

Clinical features Clinically, the affected mucosa is covered with a white membrane due to necrosis. The necrotic epitheliumcan easily be scraped off, leaving a red, bleeding surface. The lesions are painful. The diagnosis should be made on the basis of the clinical features and history.

Differential diagnosis Necrotizing ulcerative gingivitis and stomatitis, materia alba, candidiasis, mechanical trauma, bullous diseases.

Treatment Treatment is symptomatic.
Aspirin Burn

Phenol burn

Trichloroacetic acid burn
 

Candidiasis

Definition Candidiasis is the most common oral fungal infection. Over the last two decades, the disease has taken on major importance.

Etiology It is usually caused by Candida albicans, and less frequently by other fungal species (C. glabrata, C. krusei, C. tropicalis, C. parapsilosis). Predisposing factors are local (poor oral hygiene, xerostomia, mucosal damage, dentures, antibiotic mouthwashes) and systemic (broad-spectrum antibiotics, steroids, immunosuppressive drugs, radiation, HIV infection, hematological malignancies, neutropenia, iron-deficiency anemia, cellular immunodeficiency, endocrine disorders).

Clinical features Oral candidiasis is classified as primary, consisting of lesions exclusively on the oral and perioral area, and secondary, consisting of oral lesions of mucocutaneous disease. Primary candidiasis includes five clinical varieties: pseudomembranous, erythematous, nodular, papillary hyperplasia of the palate, and Candida-associated lesions (angular cheilitis, median rhomboid glossitis, denture stomatitis). The main forms of candidiasis that produce white lesions are the following.

Pseudomembranous candidiasis is the most common form of the disease, and is clinically characterized by creamy-white, slightly elevated, removable spots or plaques. The lesions may be localized or generalized, and appear more frequently on the buccal mucosa, soft palate, tongue, and lips. Xerostomia, a burning sensation, and an unpleasant taste are the most common symptoms.
Pseudomembranous candidiasis
Nodular candidiasis
Nodular candidiasis

Nodular candidiasis is a chronic formof the disease; it appears clinically as a white, firm, and raised plaque that usually does not detach.

Mucocutaneous candidiasis is a heterogeneous and rare group of clinical syndromes, characterized by chronic lesions of the skin, nails, and mucosae, and usually associated with immunological defects. Clinically, the oral lesions appear as white and usually multiple plaques, which cannot be removed.

Laboratory tests Cytology and tissue culture examination; biopsy only in chronic cases.

Differential diagnosis Leukoplakia, hairy leukoplakia, lichen planus, syphilitic mucous 
patches, white sponge nevus, chemical and traumatic lesions, cinnamon contact stomatitis, lupus erythematosus.

Treatment Topical antifungal agents (nystatin, azole derivatives, amphotericin B). Systemic azoles (ketoconazole, fluconazole, itraconazole).

Chronic Biting
Definition and etiology Mild chronic biting of the oral mucosa is relatively common in nervous individuals. These patients consciously bite the buccal mucosa, lips, and tongue, and detach the superficial epithelial layers.

Clinical features The lesions are characterized by a diffuse irregular white area of small furrows and desquamation of the epithelium. Rarely, erosions and petechiae may be seen. The diagnosis is made clinically.

Differential diagnosis Candidiasis, lichen planus, leukoplakia, hairy leukoplakia, white sponge nevus, leukoedema, cinnamon contact stomatitis.

Treatment Recommendation to stop the habit.

Cheek Biting

Geographic Tongue

Definition Geographic tongue, or erythema migrans, is a relatively common benign condition, primarily affecting the tongue and rarely other oral mucosa sites (geographic stomatitis)

Etiology The exact etiology remains unknown. It may be genetic.

Clinical features Clinically, the condition is characterized by multiple, well-demarcated, erythematous, depapillated patches, typically surrounded by a slightly elevated whitish border, and usually restricted to the dorsumof the tongue. Characteristically, the lesions persist for a short time in one area, then disappear completely and reappear in another area. The condition is usually asymptomatic, and often coexists with fissured tongue. The diagnosis is made clinically.

Differential diagnosis Candidiasis, lichen planus, psoriasis, Reiter syndrome,
syphilitic mucous patches.
Treatment Reassurance of the patient.
Geographic tongue

Geographic tongue-Localized lesion

Geographic tongue with prominent whitish border
Hairy Tongue
Definition Hairy tongue is a relatively common disorder that is due to marked accumulation of keratin on the filiform papillae of the tongue, resulting in a hairlike pattern.

Etiology Unknown. Predisposing factors are poor oral hygiene, oxidizing mouthwashes, antibiotics, excessive smoking, radiation therapy, emotional stress, and bacterial and Candida species infections.

Clinical features Clinically, it is characterized by an asymptomatic elongation of the filiformpapillae of the dorsum of the tongue, sometimes extending over several millimeters. The color may range from whitish to brown or black. The diagnosis is made clinically.

Treatment Elimination of predisposing factors, brushing of the tongue,local use of keratolytic agents (trichloroacetic acid, podophyllin).
Hairy tongue

Hairy tongue

Hairy tongue
Furred Tongue

Definition Furred tongue is a relatively uncommon disorder, usually appearing during febrile illnesses.

Etiology The cause is not clear. Predisposing factors are febrile painful oral lesions, poor oral hygiene, dehydration, and soft diet.

Clinical features Clinically, it appears as a white or whitish-yellow thick coating on the dorsal surface of the tongue . The lesion is due to lengthening of the filiformpapillae, by up to 3–4 mm, and accumulation of debris and bacteria. Characteristically, furred tongue appears and disappears within a short period. The diagnosis is made clinically.

Differential diagnosis Hairy tongue, hairy leukoplakia, candidiasis.
Treatment Therapy of the underlying illnesses and improvement of oral hygiene.
Furred tongue
Materia Alba of the Gingiva

Definition and etiology Materia alba results fromthe accumulation of food debris, dead epithelial cells, and bacteria. It is common at the dentogingival margin. Rarely, materia alba may be seen along the vestibular surface of the attached gingiva in patients with poor oral hygiene.

Clinical features It presents as a soft, whitish plaque that is easily detached after slight pressure.

Differential diagnosis Candidiasis, chemical burn, leukoplakia.

Treatment Good oral hygiene
White plaques on the attached gingiva and the alveolar mucosa, caused by
materia alba accumulation
Fordyce’s Granules

Definition Fordyce’s granules are ectopic sebaceous glands of the oral mucosa.
Etiology It is a normal anatomical variation.

Clinical features Clinically, the granules present as multiple, asymptomatic, slightly raised whitish-yellow spots. The vermilion border of the upper lip, the commissures, and the buccal mucosa are the sites of predilection. They occur in about 80% of adults of both sexes. The diagnosis is based on the clinical features alone.

Differential diagnosis Lichen planus, leukoplakia, candidiasis.

Treatment No treatment is required.
Fordyce’s granules
Leukoedema

Definition Leukoedema is a normal anatomical variation.

Etiology It is due to increased thickness of the epitheliumand intracellular edema of the prickle-cell layer.

Clinical features Clinically, it is characterized by a grayish-white, opalescent pattern of the mucosa and a slightly wrinkled surface, which characteristically disappears when the mucosa is everted and stretched. It usually occurs bilaterally on the buccal mucosa, and rarely on the tongue and lips.

Differential diagnosis Leukoplakia, hairy leukoplakia, lichen planus.

Treatment No treatment is required.
Leukoedema of the buccal mucosa.
White Sponge Nevus

Definition White sponge nevus, or Cannon disease, is a relatively rare genodermatosis.
Etiology Genetic. It is inherited as an autosomal dominant trait.

Clinical features It presents as symmetrical white lesions with multiple furrows and a spongy texture. The lesions may appear at birth, or more commonly in early childhood. The buccal mucosa and the ventral surface of the tongue are the sites of predilection, although lesions may develop anywhere in the mouth, or even in the vaginal and rectal mucosa.

Laboratory tests Histopathological examination.

Differential diagnosis Leukoedema, leukoplakia, lichen planus, chronic biting, dyskeratosis congenita, pachyonychia congenita.

Treatment No treatment is required.
White sponge nevus

Dyskeratosis Congenita

Definition Dyskeratosis congenita, or Zinsser–Engman–Cole syndrome, is an uncommon disorder.

Etiology Genetic. It is probably inherited as a recessive autosomal and X-linked trait.

Clinical features It is characterized by hyperpigmentation, atrophic skin areas, telangiectasia, nail dystrophy, hyperhidrosis, skin and mucosal bullae, blepharitis and ectropion, anemia, and oral manifestations. The oral lesions consist of recurrent blisters, epithelial atrophy, and leukoplakia. Squamous-cell carcinoma may occur.

Differential diagnosis Leukoplakia, lichen planus, epidermolysis bullosa,
pachyonychia congenita.

Treatment Supportive.
Dyskeratosis congenita
Pachyonychia Congenita

Definition Pachyonychia congenita, or Jadassohn–Lewandowski syndrome, is an uncommon genodermatosis.

Etiology Genetic. It is inherited as an autosomal dominant trait.

Clinical features It is characterized by symmetrical nail thickening, palmoplantar hyperkeratosis, hyperhidrosis, blister formation, follicular keratosis, and oral lesions. The oral lesions appear at birth or shortly afterward, and present as thick and white or grayish-white plaques, usually on the buccal mucosa, the tongue, and the gingiva. The diagnosis is based on the history and the clinical features.

Differential diagnosis Dyskeratosis congenita, leukoplakia, lichen planus, white sponge nevus, and focal palmoplantar and oral mucosa hyperkeratosis syndrome.

Treatment Supportive.
Focal palmoplantar hyperkeratosis
Pachyonychia congenita: grayish-white lesion on the buccal mucosa
Focal Palmoplantar and Oral Mucosa Hyperkeratosis Syndrome

Definition This is a rare mucocutaneous disorder.

Etiology Genetic. It is inherited as an autosomal dominant trait.

Clinical features The main clinical manifestations are focal hyperkeratosis on the weight-bearing and pressure-related regions of the palms, soles, and oral mucosa. Rarely, thickening of the nails and hyperhidrosis may be seen. The oral lesions present as white hyperkeratotic plaques (leukoplakia), mainly on the attached gingiva, the lateral border of the tongue, and the palate. The lesions usually develop in early childhood.

Differential diagnosis Pachyonychia congenita, dyskeratosis congenita, leukoplakia.

Treatment Supportive. Retinoids may be helpful.
Focal Palmoplantar and Oral Mucosa Hyperkeratosis Syndrome
Papilloma

Papilloma appears as an exophytic, painless, usually pedunculated growth. Characteristically, the tumor has a white or normal color, with numerous fingerlike projections that form a cauliflower pattern. Papilloma is usually solitary, with a size of 0.5–1 cm.
Papilloma on Buccal Mucosa
Verrucous Carcinoma

Definition Verrucous carcinoma is a low-grade variant of squamouscell
carcinoma.

Etiology Human papillomavirus is presumably involved in the pathogenesis.

Clinical features Clinically, it presents as an exophytic white mass with a verrucous or pebbly surface. The size varies from1 cm in the early stages to very extensive lesions. The buccal mucosa, palate, and alveolar mucosa are the most common sites of involvement. Verrucous carcinoma mainly develops in smokers over 60 years of age.

Laboratory tests Histopathological examination.

Differential diagnosis Verrucous leukoplakia, papilloma, verruciform xanthoma, white sponge nevus, squamous-cell carcinoma.

Treatment Surgical excision.
Verrucous Carcinoma
Squamous-Cell Carcinoma
Squamous-cell carcinoma has a wide spectrum of clinical features. In about 5–8% of cases, it appears in the early stages as a white asymptomatic plaque identical to leukoplakia. Biopsy and histopathological examination are important for the diagnosis in these cases.

Skin and Mucosal Grafts

Definition Skin and mucosal grafts are often utilized in the oral cavity to cover mucosal defects after extensive surgery for benign and malignant tumors, or as free gingival graft.

Clinical features clinically, both forms of grafts (skin and mucosal) usually present as a whitish, or gray-white plaque. The size of the plaque depends on the size of the graft. Occasionally, the color of the skin graft is black, due to melanin overproduction. If the graft contain hair follicles, hairs may develop in the oral cavity. The tongue, buccal mucosa, palate, gingiva and alveolar mucosa are the most common sites where skin and mucosal grafts are placed. Skin graft into the oral cavity may be associated with unpleasant feelings. The diagnosis is based on the history and the clinical features.

Differential diagnosis Leukoplakia, traumatic scar, epidermolysis bullosa.

Treatment No treatment is required.
Skin and mucosal grafts

Skin and mucosal grafts

Epithelial Peeling

Definition Epithelial peeling is a relatively common superficial desquamation
(epitheliolysis) of the oral mucosa.

Etiology It is caused by the direct irritating effect of toothpastes that contain sodium lauryl sulfate or pyrophosphates. The same phenomenon may be associated with chlorhexidine mouthwash. Sometimes the lesions are idiopathic.

Clinical features Clinically, epithelial peeling presents as superficial painless white plaques or dots that can be easily lifted fromthe oral mucosa. The buccal mucosa, lip mucosa, and mucobuccal and mucolabial folds are more frequently affected. The lesions usually disappear when the individual stops using these toothpastes or mouthwashes. The diagnosis is based entirely on the history and the clinical features.

Differential diagnosis Chemical burn, chronic biting, candidiasis, leukoplakia.
Treatment Discontinuation of responsible toothpastes or mouthwashes.
Mucosal Peeling


Sabtu, 12 November 2011

Core restorations-Restorative Dentistry Lecture note

A core is the term used to describe the restoration that is placed in order to build up a broken down tooth before receiving an indirect restoration. In some cases it may not be necessary to place a separate core, but an indirect restoration may be constructed to replace all of the missing tooth structure. Typical examples of this include root-filled teeth in which an integral corono-radicular restoration and core may be placed, or for teeth that have suffered cusp fracture where placement of a traditional restoration would leave very little tooth structure (e.g. premolars with a previous mesio-occlusodistal restoration and one lost cusp, a ‘one-piece’ onlay may be the treatment of choice). However, for most teeth requiring an indirect restoration, a core restoration will need to be provided.
The exact nature of any particular core will depend on the degree to which the tooth in question is broken down and how much coronal dentine remains. When attempting to understand the rationale for choice of core restoration, it is helpful to consider the concept of extremes, from a simple space-filling core to a structural core (Fig. 5.3) and relate the different functions to the materials available.

Core Build up Video
Space-filling core
When much coronal dentine remains, the role of a core is simply to fill out any undercuts and give an appropriate shape that will provide adequate retentive and resistance form (described later). The restorative material simply acts to prevent or ‘block out’ any undercuts to the path of insertion of the intended indirect restoration. This situation commonly arises when an intra-coronal restoration (i.e. an inlay) is planned to replace a previous direct restoration. The preparation will have to be modified to eliminate the undercuts; extending the preparation would be unnecessarily destructive compared with placement of a core material to block out the undercuts. Similarly, the same approach can be taken to give smooth axial walls when an extra-coronal restoration such as a full coverage crown is planned.
In the above example, the functional demands and stresses encountered by the core material will be minimal. The mechanical properties of a core material in this situation are not critical, and the material choice is largely determined by secondary factors such as ability to bond to tooth structure, cariostatic properties and ease of handling (e.g. command set).
 
Types of core restorations, (a) structural and (b) space-filling.

Structural core
When a large amount of coronal dentine has been lost, it is more likely that an extra-coronal full-coverage restoration will be planned. The core material will replace a substantial part of the clinical crown and will form the bulk of the final preparation. In this case, the core material will be subjected to significant functional demands and stresses, particularly in molar teeth, and must therefore have adequate mechanical properties to resist these. Although a full-coverage crown may afford some protection to the core if the margins are extended gingivally beyond the core6, this protection is limited. The strongest materials available at present are amalgam (for a direct core) or a cast metal such as gold (for an indirect core in an endodontically treated tooth).
Essentially, there are four types of direct core material available; amalgam, resin composite, glass ionomer or hybrid materials such as light-cured resin-modified glass-ionomer cement (RmGIC).

Amalgam
Amalgam has perhaps the best track record when used for substantial posterior core build-ups. Amalgam has good contrast with tooth substance and is easy to prepare. The long time to full set may predispose to early fracture, which is unfortunate, as the preparation cannot usually be prepared at the same visit, although newer high-copper amalgam alloys have high strength within a short time and may be prepared at the same visit after a short delay. The thermal expansion of amalgam is quite dissimilar to dentine, and this factor may predispose to failure after a period of time. In addition, amalgam cannot be bonded to tooth substance without resorting to proprietary products for amalgam bonding.


Resin composite
The use of resin composite as a core material has advantages and disadvantages. The composite does not require a two-visit crown preparation technique and, when necessary, the crown preparation can be commenced immediately. However, against this, the resin composite is difficult to prepare to the correct form because it may be difficult to differentiate between tooth tissue and core substance, though resin composites of contrasting colour are available. Lightcured resin composites should be used with caution, as full depth of cure may not be achieved in substantial core build-ups. Chemicalcure or dual-cure resin composites (the latter having the advantage of ‘command set’) have an advantage in that those portions of the material not exposed to the curing light will still undergo polymerization due to the chemical cure. However, they may undergo increased discoloration (due to the tertiary amine activator7) compared with light-cured resin composites and thus should be used with caution in anterior teeth in which non-opaque aesthetic restorations are planned. Some resin composites are marketed specifically for core build-up, are coloured and have advantages over tooth-coloured composites. It has been suggested that because of water sorption and expansion, additional die relief should be provided during construction, or impression taking should be delayed after preparation to prevent discrepancy between the working die and the prepared tooth.

Glass ionomers and resin-modified glass-ionomer cement
Traditional glass-ionomer cements are only suitable for use as a space-filling core, where they will not be subjected to any stresses, as they are inherently weak materials. Several glass-ionomer materials are marketed specifically for use as a core build-up material such as RmGIC. They bond to dentine, release fluoride, have comparable thermal behaviour to dentine, can be made a contrasting colour to tooth (e.g. blue) and are easy to prepare, although the long-term behaviour of these materials is not well documented. Water sorption and expansion are higher with these materials than with resin composites and, for this reason, after preparation there should be a delay before impression taking. At present, their use as a structural core may be questionable. However they may eventually become the materials of choice with further developments.

Choice of core material
The choice of core material depends on several clinical variables. The role of the core material with regard to a space-filling or functional role is critical and the degree to which the core will be subjected to stress and the amount of bracing provided by remaining coronal dentine should be considered when selecting the material. Amalgam alloy should not be used beneath anterior full-veneer crown restorations as corrosion products from the amalgam core may stain the dentine peripheral to the restoration and result in poor aesthetics.
Similarly, an amalgam core underneath a three-quarter crown may shine through the remaining tooth and be unaesthetic. Restoration of the endodontically treated tooth is covered in detail in later posts, though points of particular relevance are repeated here. In most situations the general principles above apply. When little tooth structure remains it is usual to place a post-retained core, although molar teeth may successfully be restored with an amalgam dowel core (Nayyar core). If a direct intra-radicular post has been placed in order to retain a core, then care should be taken to ensure that the properties of the core material are not mismatched to those of the post (e.g. avoid glass-ionomer cement or resin-composite cores with metal intra-radicular posts), although some studies suggest that fibre posts (with a relatively low modulus of elasticity) perform better with a rigid metal core.
In general terms, when there is sufficient coronal dentine remaining to provide some support to the core material, then resin-based restorative materials are the core materials of choice. However, for a tooth that has lost much coronal tooth structure then a stronger core material (amalgam or cast metal if root treated) should be placed.

Rabu, 09 November 2011

Anatomy and Physiology of the Salivary Glands and Sialography


Types of salivary glands

The Major Salivary Glands
  • Parotid
  • Submandibular
  • Sublingual
The Minor SalivaryGlands
 
Embryology
  • 6th-8th Weeks of Gestation
  • Parotid
    • First to develop
    • Last to become encapsulated
  • Autonomic Nervous System Crucial
Anatomy of Parotid Gland
  • Wedge shaped with 5 processes
    • 3 Superficial
    • 2 Deep
  • Parotid Compartment
    • Superior – Zygoma
    • Posterior – EAC
    • Inferior – Styloid, ICA, Jugular Veins
  • 80% overlies
  • Masseter & Mandible
  • 20% Retromandibular
  • Stylomandibular,Tunnel, Isthmus of Parotid
  • Tail of Parotid
Parapharyngeal Space
  • Prestyloid Compartment
  • Poststyloid Compartment (Paragangliomas)
Stensen’s Duct
  • Arises from anterior border
  • 1.5 cm inferior to Zygomatic arch
  • Pierces Buccinator at 2nd Molar
  • 4-6 cm in length
  • 5 mm in diameter
Parotid Capsule
  • Superficial layer Deep Cervical Fascia
  • Superficial layer
  • Deep layer
 


CN VII-Facial nerve
  • 2 Surgical zones
  • 3 Motor branches
  • immediately
  • Pes Anserinus – 1.3 cm
  • Temperofacial Division
  • Cervicofacial Division
  • 5 Terminal branches
Localization of CN VII
  • Tragal pointer
  • Tympanomastoid suture
  • Posterior belly Digastric
  • Styloid process
  • Retrograde dissection
  • Mastoidectomy
  • Great Auricular nerve
  • Auriculotemporal nerve
    • Superficial Temporal vessels
    • Frey’s Syndrome
Neural compartment-VII, Great Auricular, Auriculotemporal
Venous compartment-Retromandibular vein
Arterial compartment-Superficial Temporal/Transverse Facial

Lymphatics
  • Paraparotid & Intraparotid nodes
  • Superficial & Deep Cervical nodes
Submandibular Gland-Anatomy
 
  • The ‘Submaxilla’
  • Submandibular Triangle
  • Mylohyoid ‘C’
  • Marginal Mandibular branch
  • Capsule from superficial layer of Deep Cervical fascia
Wharton’s duct
  • Exits medial surface
  • Between Mylohyoid & Hyoglossus
  • 5 cm in length
  • Lingual nerve & CN XII
Innervation
Superior Cervical Ganglion (symp)
Submandibular Ganglion (para)
Artery: Submental branch of Facial a.
Vein: Anterior Facial V nerve.
Lymphatics: Deep Cervical and Jugular chains
Facial artery nodes
Between Mandible & Genioglossus
No capsule
Ducts of Rivinus +/- Bartholin’s duct
Sialogram not possible
Innervation: Same as Submandibular
Artery/Vein: Sublingual branch of Lingual & Submental branch of Facial
Lymphatics: Submandibular nodes

Minor Salivary Glands

  • 600-1,000
  • Simple ducts
  • Buccal, Labial,
  • Palatal, Lingual
  • Tumor sites:
  • Palate, upper lip,cheek
  • Lingual & Palatine nn.
Imaging of Salivary Gland-Important things to remember
  • CT – Inflammatory
  • MR – Tumor
  • Children: U/S & MR
  • NO sialogram during active infection
  • Parotid is fatty
The Secretory Unit
  • Acinus (serous, mucous, mixed)
  • Myoepithelial cells
  • Intercalated duct
  • Striated duct
  • Excretory duct
Microanatomy of Salivary glands
  • Striated & Intercalated ducts well developed in serous, NOT mucous glands
  • Striated duct: HCO3 into, Cl from lumen
  • Intercalated duct: K into lumen, Na from lumen, producing hypotonic fluid
  • Excretory ducts do NOT modify saliva
 
The Bicellular Theory
  • Intercalated duct
  • Excretory duct
The Multicellular Theory

Parotid: serous & fatty
Submandibular: mixed serous
Sublingual: mixed mucous
Stroma: Plasma cells

Function of Saliva
  1. Moistens oral mucosa
  2. Moistens & cools food
  3. Medium for dissolved food
  4. Buffer (HCO3)
  5. Digestion (Amylase, Lipase)
  6. Antibacterial (Lysozyme, IgA, Peroxidase, FLOW)
  7. Mineralization
  8. Protective Pellicle
 
Effects of Salivary hypofunction
  • Candidiasis
  • Lichen Planus
  • Burning Mouth
  • Aphthous ulcers
  • Dental caries
  • Xerostomia not reliable
 
Production of Saliva

  • Primary secretion
  • Ductal secretion
  • The “secretory potential”
  • (hyperpolarizes)
  • Increased flow rate yields decreased
  • hypotonicity & K
Autonomic Innervation
Parasympathetic
  • Abundant, watery saliva
  • Amylase down
Sympathetic
  • Scant, viscous saliva
  • Amylase up
Salivary Flow
  • 1-1.5 L/day (1 cc/min)
  • Unstimulated state
  • Submandibular
  • Stimulated state
  • Parotid
  • Sublingual & minor
  • Mucin
Effects of Aging
Total salivary flow independent of age
Acinar cells degenerate with age
Submandibular gland more sensitive to metabolic/physiologic change
Unstimulated salivary flow more greatly affected by physiologic changes

Sialography
Radiologic examination of the salivary glands
The submandibular and parotid glands are investigated by this method
The sublingual gland is usually not evaluated this way-Difficulty in cannulation

Indications
  • Ductal obstruction-Stones or tumors
  • Inflammation of a duct or gland
Contraindications
  • Severe infection of a gland
  • Known allergies to contrast media
Equipment
  • Fluoroscopic unit w/spot film capabilities
  • Cannula for introducing contrast
  • Connecting tubing
  • Lemons
  • Dilators for duct
  • 5 mL syringe
  • Overhead light
  • Gauze
  • Contrast
Preliminary and Procedure Radiographs
  • Parotid-Tangential
    • Perpendicular to cassette, directed to lateral surface of mandibular ramus
  • Submandibular-Lateral
    • Perpendicular to cassette, directed to 1 in. superior to mandibular angle to demonstrate parotid gland
    • Inferior margin of mandibular angle to demonstrate the submandibular gland
Patient Preparation
  1. Thorough explanation of examination
  2. Any removable dental work, jewelry, and other artifact causing opaque items must be removed
  3. Consent must be signed
Procedure
  • The patient first sucks on a lemon wedge to open the ducts
  • An overhead lamp is used to provide adequate light
  • The duct is cannulated, not punctured, and contrast is introduced with fluoroscopic guidance
  • Radiographs are obtained
  • After the radiographs, the patient then sucks on a lemon wedge to evacuate the contrast
  • Obtain post-procedure radiographs as indicated
Lateral Parotid Gland Radiograph


Lateral Submandibular Glands