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Applied anatomy

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  • 1. APPLIED ANATOMY AND BEHAVIOURAL CHANGES OF ORAL MUCOSA UNDER COMPLETE DENTURE PROSTHESIS Introduction - Preservation of the residual structures of foundational tissues constitute a consideration of paramount interesting prosthodontics. - Tissues of the oral cavity are made to reveal a phenomenon of reaction consequent to being subjected to artificial environment. - The reaction of the tissues is universally evident from the fact that the oral tissues will expel the irritant, big or small which enters the oral cavity. - Oral tissues were designed to be exposed to oral fluids and to be stimulated by the action of tongue, cheeks and lips. - Even in the dentulous state, the mucosa demonstrates a low tolerance to injury or irritation. Tolerance is further depleted if systemic disease is present. - Oral mucosa does not appear to be suited to the role of bearing stress and shows little or no adaptation to this altered function. - The observations I would like to make in the following delibration are based on the reaction of localized areas of these foundations to the dentures which would mean the applied anatomy. 1
  • 2. - Body cavities that communicate with the external surface are lined by mucous membranes, which are coated by serous and mucous secretions. - The oral cavity is lined with an uninterrupted mucous membrane which is continuous with the skin near the vermillion border of the lips and with the pharyngeal mucosa in the region of the soft palate. - Like skin, the oral mucosa serves to protect the underlying organs and to receive and transmit stimuli from the environment. Development of oral mucosa - The primitive oral cavity develops by fusion of the embyonic / timodeum with foregut after rupture of buccopharyngeal membrane. This occurs at about 26 days of gestation. So the primitive oral cavity is lived by epithelium derived from both ectiderm and endoderm. - The structures that develop from the brachial arches. Eg. Tongue are covered by epithelium derived from endoderm whereas, the epithelium covering the palate, checks and gingivae are derived from ectoderm. The underlying ectomesenchyme of the epithelium forms the connective tissue of the oral mucosa. 2
  • 3. Structure - Structure of oral mucous membrane resembles the skin in many ways. It is composed of : Epithelium, Connective tissue (Lamina propria) and submucosa (may or may not be present). - The 2 layers form an interface that is folded into cormgations. Papilla of connective tissue protrude toward the epithelium carrying blood vessels and nerves. Although the nerves actually pass into the epithelium, it does not contain blood vessels. The epithelium inturn is formed into ridges that protrude towards the lamna propria. Lamina propria Lamina popria may attach to the perosteum of the alveolar bone, or it may overlay the submucosa which varies in different regions of the mouth. Submucosa - Submucosa consists of connective tissue of varying thickness and density. It attaches the mucous membrane to the underlying structures. Whether this attachment is loose or firm depends on the character of the submucosa. 3
  • 4. - Glands, blood vessels, nerves and also adipose tissue are present in the layer. It is in the submucosa that larger arteries divide into smaller branches which then enter the lamina propria. - Keratinizing oral epithelium has 4 layers (based on morphology) 1) Stratum basale, 2) Stratum spinosum 3) stratum granulosum 4) Stratum corneum. A single cell after mitosis may remain in the basal layer and divide again or it may become determined during which it migrates upwards. During its migration it becomes committed to biomechanical and morphologic changes and forms a Keratinzed lquama, a dead cell filled with densely packed protein. After reaching the surface it desquamates. This whole process from onset to maturation stage is called Keratinization. Epithelium - Epithelium of oral mucous membrane is stratified squamous epithelium. It may be ortho keratinized, parakeratinized or nonkeratinized depending on the location. - A common feature of all epithelial cells is that they contain keratin intermediate filaments as a component of their cytiskeleton. Keratin: It is a sdeiroprotein which is principal constituent of epidermis, hairs, nails and organic matrix of tooth enamel. It is a very insoluble 4
  • 5. protein. It contains sulphur. KERATIN IS THE END RESULT OF EPITHELIAL DEGENERATION. The layers mentioned above are characteristic of orthokeratinization. - The cell layers o non – keratinizing epithelium are referred to as stratum basale, stratum intermedium, stratum superficiale (No stratum granulosum). Surface cells are mediated and show no signs of keratinization. - In parakeratinization, a stratum granulosum is generally absent and the surface cells retain a pyknotic nuclei and show some signs of keratinzation. Basal cells: Single layer of cuboid or high cuboidal cells. They are separated from the connective tissue by the basement membrane. Spinous cells: Irregularly polyhedral and larger than the basal cells of the 4 layers, this layer is most active in protein synthesis. Granular cells: Contains flatter and wider cells. These cells are larger than spinous cells. This layer is named for its basophilic keratohydro granules. Cornified cells: Made up of keratinized squamae which are flatter than granular cells. Here all the nuclei and other cell organelles have disappeared. 5
  • 6. While the term “Keratinization” is physiologic, the term keratosis is pathologic. When keratinization occurs in a normally non keratinized tissue, it is referred to as “keratosis”. Classification of oral mucosa in the edentulous Most classifications divide the oral mucosa into 3 categories, depending on its function and location. A) Masticatory mucosa: (Has well defined keratinized layer) Covers the crest of the residual ridge, including the residual attached gingival that is firmly attached to the supporting bone, and the hard palate. B) Lining mucosa: (Devoid of keratinized layer) It is associated with those parts of the oral cavity which are not firmly attached to the perosteum. It covers the lips and cheeks, vestibular spaces, the alveolingual sulcus, the soft palate, the ventral surface of the tongue and unattached gingival found on the slopes of residual ridges. These tissue are freely movable because of the elastic nature of underlying lamina propria. C) Specialized mucosa: It covers the dorsal surface of the tongue. This mucosal covering is keratinized and includes the specialized papillae on the upper surface of the tongue. 6
  • 7. Clinical topography of the soft tissues of the oral cavity with their microscopic anatomy and clinical importance. - Clinical procedures used in making impressions are directly related to gross anatomic structures of the oral cavity and their function. - However, the response of the individual cellular components that make up the basal seat determines the ultimate success of the dentures in terms of preservation of the residual ridges and comfort of the patient. Thus a constant awareness of microscopic anatomy of the mucous membrane and bone that form the residual ridge is essential in the development of (1) border form and (2) length and in (3) selective placement of pressures on the basal seat during impression procedures. - The nature of the mucous membrane in different parts of the mouth varies between patients and within the same patient. The keratinized layer of the epithelium may be totally absent in some instances and extremely thick in others. - Although the importance of the mucosa from a health stand point cannot be neglected, the thickness and consistency of the submucosa are largely responsible for the support that the soft tissues afford the dentures, since in most instances the submucosa makes up the bulk of the mucous membrane. 7
  • 8. - When the submucosal layer is thin over the bone, the soft tissues will be non resilient and small movement of the dentures will then to break the retentive seal. - When the submucosal layer is loosely attached to the periosteum of the residual ridge or is inflamed or edentulous, the tissue is easily displaceable and the stability and support of the dentures are adversely affected. - Impression procedure requires modification to accommodate these changes in the submucosa. I. Maxilla A. Supporting Structures 1. Crest of the residual ridge: In healthy mouth it is firmly attached to the periosteum of the bone of maxilla. It presents a grayish pink tissue because of its dense character and minimal vascularity. - Stratified sqaumous epithelium is thickly keratinized submucosa is devoid of fat or glandular cells, but it is characterized by dense collagenous fibres. Though the submucosa is thin, it is still sufficiently thick to provide adequate resiliency for primary support of upper denture. 8
  • 9. 2. Slopes of the residual ridge: Here the tissues are loosely attached. This marks the end of residual attached mucous membrane. The tissues here are non keratinized or parakeratinized. These loosely attached tissues will not withstand the forces of mastication or other stresses transmitted through the denture basis. - Mucosa of the labial vestibule between the residual alveolar ridge and the lips and cheeks is called the valve producing area. Less stress is placed on the movable tissues during making of the final impression. This is because the final impression material in that region is close to escape ways. This fact is in accordance with the principle. 3. Hard palate: - Mucous membrane of the hard palate is tightly fixed to the underlying periosteum and therefore immovable. However its thickness and consistency varies in different locations. - Epitheliumis uniform and has a well – keratinized surface - Various regions in the hard palate differ because of the varying structure of the submucous layer. These zones are recognized. a. Anterolateral area or fatty zone 9
  • 10. b. Posterolateral area or glandular zone c. Palatine raphae or median area. a. Anterolaterally: Submucosa of the hard palate contains adipose tissue. b. Posteriorly : Submucosa contains glandular tissue. Importance: These tissues should be recorded in a resting condition because when they are displaced in the final impression, they tend to return to normal form within the completed denture base, creating an unseating for on the denture or causing soreness in the patient’s mouth. The secretions from the palatal glands can be an important factor in the selection of final impression material. c) Median palatal suture: It extends from the incisive papillae till the posterior region on the hard palate. - The submucosa in this region is extremely then the mucosal layer is practically in contact with the underlying bone. So the tissue covering the suture is non-resilient. Importance: Little or no pressure can be placed in this region during making of final impression or in the completed denture. Otherwise the denture will tend to rock over the center of the palate when vertical forces are applied to the teeth. 10
  • 11. In addition this part of the mouth is highly sensitive and excessive pressure can create excruciating pain. So proper relief in the impression tray is required for accommodation of histologic nature of this tissue. 4. Incisive Papillae: At the anterior end of median palatal suture, there is an elongated or oral elevation of the mucosa called incisive papillae. It covers the incisive foramen and is located behind and between the central incisors. The submucosa of the nasopalatine canal would reveal the nasopalatine nerves and vessels. Importance: Relief should be provided for the incisive papillae in both the final impression and completed denture to prevent pressure on the nasopalatine vessels and nerves. 5. Palatine rugae: Rugae are irregularly shaped rolls of soft tissue in the anterior part of the palate. Importance: Rugae is considered to be the secondary stress bearing area as it can resist forward movement of the denture. B. Limiting structures 1. Vestibular spaces: It is bounded facially by the mucosa of the lips and cheeks and orally by the mucosa of the residual ridge. 11
  • 12. - The vestibule is partly divided in the median plane by the upper and lower labial frenae and laterally by buccal frame. - A histologic section in this region shows a relatively thin epithelium that is non keratinized submucosal layer is thick and contains large amounts of loose areolar tissue, and elastic fibres. So this tissue is easily movable. Importance: Labial or buccal flanges of the maxillary impression can be easily overextended or underextended. A knowledge of the size of the space in the vestibule available for denture flanges is the key factor. 2. Vibrating line: It is an imagninary line drawn across the soft palate that marks the beginning of motion when the patient says “ah”. Submucosa in this region contains glandular tissue similar to that in the submucosa in the postero lateral part of the hard palate. Importance: Because the soft palate does not rest directly on the bone, the tissue for a few millimeters on either side of the vibrating line can be repositioned in a controlled manner in the impression procedure. This improves posterior palatal seal. 12
  • 13. 3. Mucous membrane in Hamular notch area: Space between the posterior part of maxillary tuberosity and pteregord hamulus is thick and made of loose aredor tissue. Importance: Additional pressure can be placed on this tissue at the center of the notch to complete the posterior palatal seal. Spacer is provided in the find impression tray except in the region of vibrating line and through hamular notches. Thus the tray itself contacts the soft tissue in this region when impression is made. These tissues can be displaced without trauma. II. Mandibular edentulous foundations A. Supporting structures 1. Crest of the residual ridge: Mucous membrane covering the crest of the lower residual ridge is similar to that of the upper ridge. In a healthy mouth it is covered by a Keratinized layer firmly attached to the periosteum by the submucosa. In same patients the submucosa is loosely attached to the bone over the entire crest of the residual ridge and the soft tissue is quite movable. Importance: when the soft tissues is movable, it must be registered in its resting position in the final impression. Occasionally surgical 13
  • 14. procedures are indicated to increase the amount of “residual attached gingivae”. These tissues must be in a healthy condition when the final impression is made. 2. Buccal Shelf: Mucous membrane covering the buccal shelf is more loosely attached and partially keratinized and contains a thicker submucosal layer. However the bone of the buccal shelf is covered by a layer of compact bone composed of Haversian system. Hence this area is suitable as a primary stress bearing area of the mandibular edentulous foundations. B. Limitating structures: 1. Vestibular spaces: The mucous membrane lining these spaces is quite similar to the in nature to that of the maxillary foundation. The epithelium is their and non Keratinized and the submucosa is formed of loosely arranged connective tissue fibres and elastic fibres. Anteriorly the submucosa of the mucous membrane lining the alveolingual sulcus contains components of the sublingual gland and is attached to the genioglossus muscle. 14
  • 15. 2. Molar region: Here the submucosa attaches to the mylohyoid muscle and mucous membrane covering the retromylohyoid certain is attached by its submucosa to the superior constrictor muscle. Posterior to the superior constrictor muscle fibres, when run in a horizontal direction is found the medial pteregoid muscle running in a vertical direction. Importance: Length and form of the lingual flange of the lingual flange of lower final impression tray must reflect the physiologic activity of these structures. 3. Retromolar pad: It has at the posterior end of the crest of lower residual ridge. Histologically mucosa of the pad is composed of a thin, non keratinized epithelium. Its submucosa contains glandular tissue, loose areolar tissue, fibres of baccinator and superior constrictor muscles, the pteregomandibular raphae and the tendon of temporalis. Importance: because of its contents, it is recorded in a resting position in final impression. Behaviour of oral mucosa under stress - Oral mucosa under compression behaves in a viscoelastic fashion similar to skin and other biologic tissues loaded in compression. 15
  • 16. - Loads imposed on the masticatory mucosa by normal mastication and by the prosthesis consists primarily of compressive and shear forces. However these forces will produce regions of tensile stresses within the mucosa. - Kydd and associates described the viscoelastic character of denture supporting tissues. a. There is an initial elastic compression of the soft tissue that takes place instantly on application of load. b. After the elastic phase there is a delayed elastic deformation of the soft tissue that takes place slowly and continues to diminish in rate of change as duration of load is extended. c. An instantaneous elastic decompression occurs when the pressure is removed. d. This is followed by a continuing delayed elastic recovery. - They also arranged that during function and parafunction, pressures are applied by the dentures which will displace the soft tissues. These pressure deform the mucoperiosteum and interferes with circulation of blood, nutrients and metabolites. Tissue pressure under complete maxillary dentures 16
  • 17. - Cutright and associates (1976) recorded pressures under complete maxillary dentures. They used a closed fluid system connected to a pressure transducer and recorder to register positive and negative pressures in 4 subjects at 4 locations. - Each subject performed a number of controlled masticatory and non masticatory activities. - Pressures were recorded as positive above a base line which equaled zero with the denture in a passive condition and negative if they were below the base line. - Findings indicate that a number of non masticatory activities (swallowing, smoking and speaking) created as much or more +ve or –ve pressures on the supporting tissues as the masticatory activities. Conclusion of this study 1. Stable dentures produce high pressure on the supporting tissues and transmit these pressure from region to region varying with how the patient uses the denture. 2. Most often, an opposite large or negative pressure immediately followed the production of + ve pressure at the same site beneath the denture. Thus each movement actually traumatizes the tissue twice. 17
  • 18. 3. Swallowing which is not associated with eating or drinking produced very high +ve and very low –ve pressures on the tissues. Effect of complete denture on alveolar mucosa - Ostland studied the effect of complete dentures on the “gum tissues” through observation of clinical changes and the examination of histologic sections from biopsies of palatine mucosa in denture and non denture wearers. - He described the mucosal changes as pathologic but without frank clinical inflammation. He demonstrated a decrease in Keratinization of denture bearing mucosa and a decrease in mucosal thickners. Conclusion: He concluded that a denture covering the ridge mucosa in the absence of trauma protects underlying soft tissues from injury. So in a non denture wearer  irritation from various sources  chronic inflammation  More boneloss. So because of continuous inflammation a non denture wearer may loose more bone than a denture wearer. - Kapur and associates conducted a study to investigate the changes occurring in denture bearing mucosa after the use of removable dentures. Biopsy study was performed before and after the use of dentures. (Biopsy form crest of the ridge). - One side of posterior edentulous ridge was stimulated with a power driven tooth brush on week days for a period of 4 weeks. The other 18
  • 19. side served as control. This was done in order know the relation between tissue stimulation to wearing of dentures. (In a previous study it was demonstrated that stimulation of edentulous alveolar mucosa with an automatic tooth brush resulted in increased keratinized). Alveolar mucosa prior to denture insertion Microscopic examination revealed a) A distinct layer of keratin. This was of parakeratotic variety with cell nuclei visible within stratum comeum. b) Connective tissue was infiltrated with varying numbers of lymphocytes, plasma cells – chronic inflammatory cells. c) Edentulous mucosa that had been stimulated with automatic tooth brush for a period of a 4 weeks showed a generalized increase in width of stratum corneum as compared to unstimulated mucosa. d) Stimulated mucosa also showed greater downward extension of rete pegs than unstimulated mucosa. Alveolar mucosa following the wearing of dentures for 3 months 19
  • 20. Microscopy showed a) Distinct increase in width of stratum corneum in specimens taken after dentures had been worn. It was mainly orthoKeratin (hyperortho Keratinization) but it was mainly orthoKeratin (hyperorthokeratinization) but zones of parakeroatosis were occasionally in evidence. b) The stimulated and non stimulated mucosa presented an equal amount of keratinization indicating that the stimulation of mucosa prior to insertion of dentures had no relationship to subsequent tissue reaction. c) Chronic inflammatory infiltration was minimal and connective tissue collagen appeared dense and well formed. Conclusion: These results are in some variance with those of ostland. Since ostlund’s biopsies were taken in posterior palatal seal areas, the changes may have been due to continuous pressure from denture base in this region Biopsy specimens of the ridge (as in Kapur’s study) presents a more accurate picture of mucosal reactions to well-adapted dentures. It keratinization is a mechanism where by tissues gain a greater degree of protection against local irritation or trauma, then it appears a well adapted denture base stimulates, the underlying mucosa to produce keratin. 20
  • 21. Lack of inflammation in subjacent C.T. indicates that well adapted denture is not an irritant. Biomechanical principles of denture construction, its relation to keratinization - The purpose of this study conducted by markov was to see whether amount of keratinization of edentulous ridges had something to do with biomechanical qualities of dentures such as occlusion, stability, vertical dimension of occlusion, palatal relief in maxillary denture. - Smears were made from tissues scrapings collected from mucosa and were stained and examined microscopically. Conclusion: Fundamental biomechanical principles of good denture construction are of paramount importance to the health of the mouth under complete dentures. The principles include, 1. Good Occlusion 2. Stability 3. Establishment of correct vertical dimension of occlusion 4. Palatal relief in the midline of maxillary denture. 21
  • 22. Histological changes of oral mucosa under stress. Significant changes occurred in the epithelium and connective tissue depending on the amount of force applied. Epithelium: under 5g/mm2 of force epithelium showed no cytologic changes until a 4 hour load duration was reached. At this stage intercellular and intracellular Changes were seen Changes consisted of vacuolization, decreased staining of cytoplasm, cellular swelling and increased nuclear size. The parts of epithelium in which these changes took place were the middle and upper layers of stratum spinosum. Cells of basal layer appeared unaffected. At 6 hours duration, isolated damaged cells were more frequent. Lamina propria and submucosa: - Length and width of papilla appeared o be decreaed. Sometimes they were completely obliterated. - Submucosa of mucoperiosteum that contained major blood vessel was completely occluded under heavy loading. 22
  • 23. Conclusion: with relatively small occluding forces (0.29/mm2) the denture supporting oral mucosa can be intruded upto 20% of resting thickness. This indicates that impression materials must flow readily with minimal pressure when an impression is made. Denture inflammation and associated soft tissue changes Response of human skin to everyday wear and tear is to become keratinized and tough. The oral mucosa does not behave in the same manner. Even the dentulous state, the mucosa demonstrates a low tolerance to injury or irritation. This tolerance is further reduced if systemic disease is present. The mucosa does not appear to be suited to complete-denture load bearing rate and demonstrates little or no ability to respond to this altered function. It appears that if the tolerance of the mucosal tissues is exceed (eg. By overextended border), injury and inflammation will result and the denture cannot be worn. If on the other hand, initial tolerance is high and the trauma tolerable, a fibrous response is elicited and the residual ridge is replaced with flabby hyperplastic tissue. Dentures are frequently worn over such tissue without discomfort. In between these two extremes be the majority of patients, in whom chronic mucosal irritation proceeds quietly and painlessly. 23
  • 24. It may be the character of the underlying bone that determines the tolerance and response of denture bearing mucosa. Bergman and associates showed a causal relationship between trauma and denture stomatitis and that stomatitis was greater in those patients in whom the residual ridge was displaceable. Soft tissue to long term denture wearing which are frequently encountered are A. Soft tissue Hyperplasia B. Denture Stomatitis A. Soft tissue hyperplasia: Hyperplasia of the soft tissue under or around a complete denture is the result of a fibroepithelial response to complete denture wearing. It is often asymptamatic and may be limited to the tissues in the vestibule or palatal regions or it may occur on all or part of the residual ridge. i) Fibrous hypoplasia on ridge crest - It consists of rolls of hyperplastic tissue under the denture base. - Lesion is slow to develop and painless 24
  • 25. - It may be due to bone resorption, with the lesion filling the space under the denture base caused by bone loss. - It is most often found on anterior part of maxillary ridge. - A single maxillary denture opposed by natural lower anterior teeth only will usually lead to formation of this tissue. Treatment: Early stage - Tissue recovery period may be all that is necessary. Advanced stage (Tissues allow excessive denture movement) - Surgical removal - New dentures are constructed. ii) Epulis fissurata: - It is the hyperplasia occurring around the border of a denture. - It occurs in the free mucosa lining the sulcus or at the junction of free and attached mucosa. - It develops as a result of chronic irritation from overextended dentures. - Clinical examination reveals, these tissue are hyperaemic and swollen. 25
  • 26. Treatment: Incipient-stage - Impound dentures, until healing is complete - Dentures may be worn with tissue conditioner after removal of the irritant. Chronic stage - Surgical removal, Care must be taken to avoid excising any attached mucosa. - Dentures can be worn as surgical dressing - Remake the prosthesis The flabby hyperplastic tissues found in denture wearers should be excised to minimize progressive resorption of residual ridges. iii) Papillary hyperplasia: - It is a granular type of inflammation seen in the palatal regions of maxillary arch. - It consists of numerous closely arranged papillary projections that give the region a warty appearance. - Factor most likely to be involved in the formation of papillary hyperplasia is negative pressure. A similar condition exists when relief chambers are made in palatal regions of max, denture. When a 26
  • 27. palatal relief is provided, the edge of the relief not be detectable to the finger tip. - This condition is not reversible. - This lesion is not innocuous. It has been suggested that these lesions show precancerous tendencies designated pathologically as pseudoepitheliomatous hyperplasia. Infrequent cases show frank carcinoma. - Some authors agree that this lesion is entirely innocuous and malignancy does not develop from this hyperplasia. Treatment: - Surgical curettage and excised tissue for microscopic examination. - Impound the dentures until healing is complete. - Relief or remake the prosthesis. - Ensure 8 hours of tissue rest per day with new dentures. B. Inflammatory process under denture bases i) Denture stomatitis: - It is a chronic inflammation of the denture bearing mucosa. It may be localized or generalized in nature. - Various causes have been suggested. 27
  • 28. Trauma from illfitting dentures, parafunctional habits, nocturnal denture wear, hypersensitivity, infection with candida albicans, and poor and hygiene. - there is redness of tissue under the denture base, with pain, buring of the tissues and metallic tastes in the mouth. - The patient may be asymptamatic also. - It tends to occur more frequently in the maxillary arch. Treatment: - Impounding dentures, so that tissues return to good health - Maticulous oral hygiene procedures. - Use of antifungal drugs. One nystabin tablet taken 3 times a day for 10-14 days is usually sufficient to control the infection. However antifungal drugs are used only after confirming infection with candida albicans. - Use of 2% solution of chlorhexidine gluconate and gingival massage with tooth brush. - New well fitting dentures, after the conditions has subsided. 28
  • 29. ii) Denture sore mouth: When one encounters mucosal complaints that do not fit into the general descreption of denture stomatitis, it is diagnosed as “denture sore mouth” syndrome. - It is diagnosed when the treatment methods just mentioned for denture stomatitis is unsuccessful. - It is probably the result of an underlying abnormal metabolic or hormonal function, a nutritional deficiency. Eg: Diabetes - Symptoms are bizarre spectrum of itching, painful, irritated and tender denture bearing areas. Clinical findings are usually negative and in such patients mucosal tolerance is very low. - Iron deficiency, insufficient protein and incomplete intestinal absorption have been cited as contributory factors. Treatment: - Patients systemic status should be investigated - Uprage quality of dietary intake - Impound dentures, until inflammation subsides. 29
  • 30. - Slow release hydrogen chloride in achlorhydric patient, ascorbic tablets dissolved sublingually may be helpful. - Therapy with liver fraction tablets may rejuninate the oral mucosa. - Refit or remake the prosthesis iii) Stomatitis venenata: Some people react differently to certain drugs and materials than others. Reactions found in the mouth to drugs and materials used have been termed “stomatitis venenata”. - Since the introduction of methyl methacrylate for dentures, some dentists have been concerned with possible sensitization of denture wearness to this material. - This material of the denture base is not a factor in mouth reactions. This opinion is supported by the clinical observation than duplicating the denture in a different material does not relieve the symptoms. - Turrell (1966), has concluded that the concentration of the residual mnomer in a properly cured acrylic resin is unlikely to elicit a clinical response. iv) Monitasis: - It is a disease entity and the occurrence of disease is related to the pathologic activity of certain monila. 30
  • 31. - It is generally agreed that, moniliasis is usually found in unclean mouths or in debilitated patients. A systemic disease such as diabetes and all unhygienic conditions will facilitate establishment of moniliasis. - All dentures materials have a significant degree of porosity. This is true whether it is acrylic or metal. Monila which are very resistant organisms, enter the porous structures and remain there for long periods. - Symptoms include redness with pain, swelling of denture supporting tissues. - It may also occur in the form of white lesions. The affected region may resemble a wet cigarette paper adhering the mucosa anywhere in the mouth. It can be carefully separated, leaving a raw red area underneath. (While lesion  chronic hyperplastic condiasis, Associated dentures stomatitis  chronic atrophic condidiasis). Treatment: - Discarding the existing dentures. - Application of gentian violet 3 times a week - Suspension of mystatin held against oral lesions 31
  • 32. - New dentures after disease has been controlled. Mechanical irritants Decubital ulcer: They result from pressures that exceed the physiological endurance of the tissues and may be very painful. - It is usually associated with insertion of new dentures. - Initially there is only slight redness at the site of the ulcer with minimum pain. If untreated the lesion becomes white due to necrosis. - This calls for scheduling the first adjustment appointment for 24 hours after insertion of new dentures. Additional visits should be scheduled as needed. Ulcerative lesions Angular cheilitis: - Dentures stomatitis is occasionally accompanied by angular stomatitis which is also known as angular cheititis or perleche. - Bilateral lesions develop at the angles of the lips. Deep fissures or cracks may develop which appear ulcerated and an exudative crust may be present. - For several years the clinical condition was though to occur due to reduction of vertical dimension of occlusion. 32
  • 33. - Bergendal (1982) has shown that this condition is usually secondary to a denture stomatitis and the result of candida infection from contaminated saliva. Treatment: Angular stomatitis responds to antifungal therapy. - Combined treatment approach to denture stomatits and angular stomatitis is mandatory. Non infections local diseases affecting oral cavity White lesions i) Leukoplakia: It is used to describe an oral lesion with a white, leathery plaque that is neither painful nor tender. - Most common sites in edentulous mucosa are the buccal mucosa and palate. Tobacco is often a causative factor. - Biopsy is mandatory as leukoplakia may show dyskeratosis. - With a negative biopsy report, the palate may be safely covered with a well fitting denture and the primary cause should be eliminated. 33
  • 34. ii) Lichen planus: Most likely to occur on the buccal surfaces of cheeks, appearing as fine lines and forming a lacy pattern which is not painful. - Lichen planus of erosive type is of far greater concern to the dentist. The lesions are very painful and occur bilaterally. Ballae may develop with painful ulcerations. - When the ulcerations are on denture supporting tissue, wearing of a denture is virtually impossible. Treatment: Topically applied corticosteroids have been recommended. - Refitting or remaking the prosthesis after healing of the lesion. iii) Hyperkeratosis May be observed in the regions of low grade chronic trauma, in particular at denture border, lesions may vary from mild keratosis to leukoedema to frank leucoplakia. Treatment: Removal of the irritant Malignant lesions: - Patients who need complete dentures are usually in the age group that is most susceptible to oral cancer. 34
  • 35. - So a routine recall of denture patients at 6 months interval is very important. - A biopsy should be made for any lesion that cannot be identified by other means. - Although tobacco is involved in the history of most of the carcinomas, patients who do not use tobacco and have illfitting dentures are seen with carcinomas. - Hobock reported 560 patients with direct intraoral epidermoid carcinomas. 204 more prosthesis and in 86 there was a direct connector between irritant by the prosthesis and development of carcinoma. They had these factors in common. a) They had worn illfitting dentures for years b) The dentures had irritated or chafed the soft tissues for a prolongued period of time. c) An epidermoid carcinoma was found in the region covered by the prosthesis or was found to be in contact with the prosthesis. Influence of systemic and nutritional factors on oral mucous membrane 35
  • 36. Evaluating the systemic and nutritional factors before starting the fabrication of denture may prevent failure of treatment. - One of the most important and simple ways of evaluating these systemic factors is by taking a proper history. This should include personal, medical and dietary information. A. Metabolic Diseases All tissues in the body are influenced to some extent by hormones and oral mucosa is no exception. Diabetes mellitus: Chronic disorder of carbohydrate metabolism. - Cause is either a deficiency of decreased effectiveness of insulin. - In some instances antiinsulin hormonous may be produced in excess which counter act the effects of insulin. - Oral lesions are non specific. There is usually a reduced resistance to trauma and healing is poor. Condidal stomatitis is often present. - The increased susceptibility to infection is probably due to elevated sugar content in tissues, alteration in amino acid pool unsetting antibody production. Treatment: Impounding of dentures until the blood sugar comes to normal level. 36
  • 37. - It impressions have to be made in these patients, a material which has good flow must be used since the tissue rebounding is more in a diabetic (MINIMAL PRESSURE TECHNIQUE). Nutritional disorders Insufficient of essential nutrients can result from defective diet, malabsorption from gut, factors inhibiting blood transport, increased metabolic need etc. Vit A: It is a well established fact that vit A is concerned primarily with process of differentiation of epithelial cells fail to differentiate. This means cells in basal layer loose there specificity. Thus one of the basic changes is keratinizing metaplisa of epithelial cells. - The epithelium of the alveolar mucosa becomes acanthotic and in prolonged deficiencies shows keratinization. Most changes described are reversible with administration of vit A to deficient patients. B Complex group i) Vit B2 (Riboflavin): - Deficiency is associated with malabsorption, chronic infection and other metabolic disorders. - Tissues of ectodermal origin are mainly affected. 37
  • 38. - Non specific glossitis and Angular chelitis are the features. Treatment: Administration of B Complex vitamin will reverse this condition. Blood Dyscrasias i) Iron deficiency: - Oral manifestations are common and many patients complain of a burning sensation especially on the tongue. - Dry mouth, angular chelitis and rarely difficulty in swallowing are seen. - Epithelial atrophy will be most evident on the tongue giving it a smooth glazed appearance. - Infection with candida albicans producing angular chelitis is not uncommon because of a defect in cell mediated immunity in anaemia. - Histological changes show atrophy of lingual papillae and chronic inflammatory cell infiltration in connective tissue is used an increase in size of nuclei is also seen. Treatment: 1. Iron therapy 38
  • 39. 2. High protein diet ii) Vit B12 deficiency: Pervicious anaemia is the commonest feature. It is caused by lack of production of intrinsic factor in the stomach. Features are similar to iron deficiency anaemia. Treatment: Administration of Vit B12. Ageing and oral mucosa - Clinical picture is that of atrophy. - Epithelial layers are less in number and the mucosa and submucosa show decrease in thickness. - The depleted repair potential renders the denture bearing mucosa and basal seat friable and easily traumatized. - Mucosa blanches easily. - So there is a reduction in surface area of oral mucosa. An atrophying denture-bearing mucosa is frequently encountered during menopause. Etiology: Reduction in estrogen output Treatment: Replacement therapy can be helpful. 39
  • 40. A change in tissue displaceability can also be demonstrated as being a function of age. A longer period of time is needed for the recovery of displaced mucosa in elderly people when compared with young adults. 40