Correction of partial dentures.
Effect of base denture on the mucosa.
After insertion of the removable denture, further correction is needed in most cases. It is explained by different degree of the mucous membrane compliance of the prosthetic bed and impossibility to take this factor into consideration while constructing removable dentures. Every dentist should carry out these additional stages.
The following inspection of the patient should be made the next day. Asking the patient the dentist gets to know his complaints and condition. Both in presence or absence of complaints the oral mucosa should be thoroughly examined. It is necessary to control the occlusion once more and correct its drawbacks. The pain in the alveolar process is often of uncertain localization and occurs in uneven distribution of the masticatory pressure.
At first, the patient’s complaints are thoroughly analyzed including complaints on phonetic, esthetic and functional character (bad fixation in biting or mastication), pain (in conversation, during meal), etc. Special attention should be paid to the pain syndrome determining its character, localization, degree. At first the dentures are inspected in the mouth without taking them out. Attention is paid to the character of occlusion relationship, degree of fixation and stabilization of the dentures. The drawbacks found are eliminated by correction of the occlusion contacts, activation of the retaining elements. Then the prosthetic bed is thoroughly inspected. The revealed areas of hyperemia of the mucous membrane, erosion or ulcer are outlined by the chemical pencil and transferred on the denture base, and then they are ground off. At present our industry manufactures a special indication paste. This paste is applied to the area of the damaged mucous membrane and covered with a denture. It leaves exact visible trace on the base indicating the area which needs correction. The contrast between a lot of patient’s complaints and absence of visible, pathological changes of the mucous membrane indicates that the patient might not wear the similar constructions of the dentures . The patient is told about complexity and individuality of the adaptation process to the removable dentures and explained the rules of their wearing.
There is no common opinion among the specialists as to removal of the dentures during night sleep. On one hand, removal of the removable dentures at night when there are separateteeth in the mouth with affection of the supporting apparatus may result in their injury and quick loss. On the other hand, permanent compression of the vessels of the submucous layer by the denture base may lead to disturbance of the tissue trophicity and enhancement of the atrophic processes. Therefore the dentist should select the most optimal variant in every case.
While treating patients with the aid of removable dentures there may be complications due to dentist’s and technical mistakes or side effects of the denture materials. In this case the patients may have the following typical complaints: unsatisfactory denture fixation, speech dysfunction, pain or burning sensation, breakdown of some denture elements, esthetic defects.
Unsatisfactory fixation (stabilization) of the removable denture may be a consequence of a number of causes: atypical shape of the abutment teeth, incorrect localization of the retainers as to the examination line, drop of the removable plate denture of the upper jaw with porcelain masticatory teeth; sagittal localization of the clamp line; dotted fixation; denture balance on the upper jaw due to sharply marked torus and absence of isolation; taking of compression impression in the atrophic mucous membrane; incorrect position of the artificial teeth in all phases of all kinds of occlusion. The abutment teeth in clasp fixation of the removable dentures must have well-expressed equator and sufficient height of the crown, otherwise the artificial dentures on them should be constructed beforehand, without plastic covering as the latter is worn out in time and retention is worsened. In case the abutment teeth are of atypical shape, e.g. triangular or of reverse cone restored with fillings on the vestibular side or affected by a wedge-shaped defect, they should be covered with crowns.
Unsatisfactory fixation of the removable plate denture may be associated with incorrect position of the retention part of the retainer as to the medium survey line, i.e. it is near to the masticatory surface or comes under the line by less than 0.25 mm in depth. To prevent atrophy under the removable dentures with unfavorable state of fixation (dotted, sagittal unilateral) it is necessary to use light plastic masticatory teeth instead of porcelain one, if possible, using telescope system of fixation – a bar of Rumpel – Dolder, clip attachments, intraroot magnets, functional formation of the base borders. It is undesirable to extract the remaining teeth on the upper jaw, especially in II and IV type of the mucous membrane by Suppley; they are devitalized, shortened to the level of the gingival margin and intraroot attachment is used: clip – in stable root, without atrophy of the parodont; magnetic – in the mobile root with signs of the parodont affection. Such additional fixation in combination with the functional formation the denture base borders contributes to improvement of its stabilization to prevent its drop (in cough, sneezing, etc).
The toxic effect of the plastic base of the removable denture on the mucous membrane may be due to bad quality of plastic polymineralization and , as a result, excessive presence of free monomer, which exerts the toxic influence. On examination of the patient there is hyperemia of the mucous membrane of the prosthetic bed but it is not of local but of the diffuse character. To eliminate increased content of the monomer there are proposed different methods of depolymineralization – repeated thermoprocessing in the cuvette, ultraviolet, ultrasound irradiation.
Hypersensitivity of the patients to the acrylic resin, which is used for removable denture base as well as to the dyes, is encountered quire frequently. Such complication cannot be considered dentists’ or technician’s mistake as it is associated with a side effect of the removable dentures, especially of the plate type.
The denture should not be dropped. In case of its breakdown the patient should go to the dentist immediately. Clasps, especially wire, may become weakened in time; therefore patients should consult a dentist once or twice a year to their straightening. In 3-4 years the denture should be changed. During the first three days after insertion the patient should visit the dentist. The follow up continues till the dentist is sure of the patient’s adaptation to the denture. Some specialists recommend the patients to refer to the dentist in case of development of pain. It is a mistake resulting in serious complications.
Pain is tolerated in different ways. Some people experience pain in considerable size of the decubital ulcer as a feeling if discomfort, the others develop pain in the slightly marked decubital ulcer, and the pain is so bad that the patient cannot sleep. In most cases ulcers heal forming a cicatrix that deforms the transition fold resulting in complicated prosthesis. Pains may disappear after correction of the artificial teeth occlusion.
The transition fold should be thoroughly examined ion the upper jaw, in the area of the alveolar tubers and the line “A”. The decubital ulcers located behind the alveolar tuber, at the site of transition of the hard palate into the soft one cause pains in swallowing. On the lower jaw the sublingual space needs careful examination starting from the tongue root to its frenulum. The decubital ulcers in the sublingual space interfere with the tongue movements, and the decubital ulcers of the lip frenulum – movements of the lips and cheeks. In some cases it helps the dentist in seeking the causes of pain.
Vomiturition is associated with irritation of the mucous membrane of the soft and rarer hard palate. Shortening the denture borders always gives a good result. Only in some cases it is difficult to struggle with this reflex. The patient is the best helper in struggle with this reflex. It may be suppressed by training.
Oral mucosal lesions associated with the wearing of removable dentures.
Lesions of the oral mucosa associated with wearing of removable dentures may represent acute or chronic reactions to microbial denture plaque, a reaction to constituents of the denture base material, or a mechanical denture injury. The lesions constitute a heterogeneous group with regard to pathogenesis. They include denture stomatitis, angular cheilitis, traumatic ulcers, denture irritation hyperplasia, flabby ridges, and oral carcinomas. Denture stomatitis is the most common condition which affects the palatal mucosa in about 50% of wearers of complete or partial removable dentures. Most of the lesions caused by chronic infection (Candida albicans) or mechanical injury whereas allergic reactions to the denture base materials are uncommon. Angular cheilitis (lesions of the angles of the mouth) is characterized by maceration, erythema and crust formation. The prevalence is about 15% among wearers of complete dentures. The lesions have an infectious origin but several local, including prosthetic, or systemic predisposing conditions are usually present. Traumatic ulcers caused by dentures with overextended or unbalanced occlusion are seen in about 5% of denture wearers. Denture irritation hyperplasia, which is caused by chronic injury of the tissue in contact with the denture border, is present in about 12% of denture wearers. Flabby ridge, which is replacement of alveolar bone by fibrous tissue, is present in 10-20%. Finally, there is evidence that chronic injury of the oral mucosa by dentures in rare instances may predispose to development of carcinomas. Most types of lesions are benign and quite symptomless. However, diagnosis may be difficult and the more severe and dramatic tissue reactions to dentures may indicate underlying systemic diseases. In order to prevent or minimize the extent of the lesions, denture wearers should be recalled regularly for an examination of the oral cavity and the dentures. It is important that the examination is carried out by a person who has adequate medical knowledge
