Odontogenic myxoma: Case report with reconstructive considerations

Odontogenic myxoma is a benign but locally aggressive neoplasm. The present case documents the resective and reconstructive management of a patient with a moderately large myxoma of the mandible.     

Evaluation of shear strength at the cement-endodontic post interface

The strength characteristics of the cement-implant interface were evaluated for smooth-tapered, threaded, and porous-surfaced endodontic implants with the use of different cements. Specifically, tensile and torsional shear strengths were measured for zinc phosphate, polycarboxylate, glass-ionomer, silicophosphate, and AH-26 cements. The results indicated superior shear strength characteristics for threaded endodontic implants on axial loading. However, this strength was diminished when torsional forces were applied. Porous-surfaced endodontic implants showed strong resistance to both axial and torsional loading.     

A clinical study to assess the ability of a powered toothbrush to remove chlorhexidine/tea dental stain

AIM: A single-center, single-blind, two-way crossover study was performed to compare the effects of an electric powered toothbrush with a conventional manual toothbrush at removing chlorhexidine/tea tooth staining. METHODS: This study used 24 subjects. During the week before the study, the subjects received a prophylaxis to remove all staining, plaque and calculus deposits. On the Monday of the following week, subjects returned to the clinic to receive a further prophylaxis. Under direct supervision, they then rinsed with a 0.2% chlorhexidine mouthrinse, immediately followed by a rinse with a warm black tea solution. This cycle was repeated hourly eight times throughout the day and on the following days until the Friday. Throughout this period, volunteers omitted all other forms of oral hygiene except rinsing with the chlorhexidine mouthwash. On the Friday, the level of stain was assessed both prior to and immediately after brushing with the allocated brush with toothpaste for 1 min. This was done in an adjoining room (out of sight of the clinical scorer). Subjects were then instructed to use the toothbrush at home according to their normal oral hygiene practices. On the following Friday, subjects returned to the clinic when the stain present was re-assessed. Each subject received a thorough prophylaxis to remove all plaque calculus and staining before starting the second period of the study and again on completion of the study. RESULTS: The study showed relatively little difference between the ability of the two brushes to remove stain at a single test brushing. However, there was some evidence that the powered brush was more effective than the manual brush in minimising stain level during the home use period, overall and in particular for gingival crescent sites. CONCLUSIONS: This study has suggested that the powered brush may become more effective at reducing dental stain, the longer the brush is used under normal home conditions.     

Host response in experimental periodontal disease

Experiments were performed to determine the role of the immune response in rat periodontal disease. Germ-free rats were fed defined antigen-free liquid diets or a diet containing ovalbumin(OVA) as a prototype antigen. The OVA-fed rats demonstrated increased gingival lymphocytes (mainly T at early times), OVA-sensitized spleen cells, and increased periodontal bone loss. In further studies, rats pre-sensitized with OVA, and receiving OVA in the diet, showed elevated IgG antibody, sensitized spleen cells, and elevated periodontal bone loss scores. The concept that bone loss was due to mixed hypersensitivity reaction is consistent with the periodontal pathology. The effects of pre-immunization with A. actinomycetemcomitans (Aa) on periodontal bone loss in Actinobacillus (Aa) - infected rats was examined. Delayed hypersensitivity (DTH) was present in immunized rats throughout the experimental period. Sham-immunized rats showed DTH after 30 days of infection. In addition, immunized rats showed elevated bone loss scores. These experiments support the contention that a combination of hypersensitivity reactions (i.e., mixed hypersensitivity to Aa) could give rise to the periodontal pathology observed. Congenitally athymic rats (nude) were shown to have more periodontal bone loss than did normal littermates. However, bone loss in thymus-cell reconstituted nude rats was not different from that in control rats. Normal rats receiving Aa-sensitized T lymphocytes prior to infection with Aa demonstrated increased DTH and periodontal bone loss. These studies support the concept that T-cell functions and thymic regulation of immune responses can exert protective and/or destructive effects in periodontal disease. In order to modify disease, it will be necessary to enhance the protective aspects of the immune response and to minimize the detrimental aspects.     

Comparison of physical properties of polycarboxylate-based and conventional root canal sealers.

Several physical properties of nine commercial root canal sealers were evaluated in vitro and were compared with those of two experimental endodontic materials based on polycarboxylate formulations. Flow, setting time, compressive strength, radiopacity, adhesion to root dentin, and solubility were evaluated. The zinc oxideeugenol root canal sealers were typically of low strength and high solubility. These sealers and the Diaket polyvinyl resin sealer showed no adhesion to dentin. The epoxy resin AH26 showed superior properties with respect to strength, flow, radiopacity, and adhesion; solubility of this material was high. The polycarboxylate formulation showed significantly higher values over the commercial sealers in properties of strength, adhesion, and reduced solubility. The tensile adhesive bond strength of the polycarboxylate to root dentin was twice that of AH26. A wide variation in properties of the commercial materials tested showed the empirical nature of these "sealers." Further testing of polycarboxylate endodontic sealers is indicated.     

Changes in occlusal face height with removable partial prostheses

If the occlusal face height is increased with removable partial dentures for patients in whom no evidence of overclosure exists, then the stomatognathic system will be adversely affected. The reaction to this increase depends on the degree of adaptation shown by the patient. If adaptation is poor, discomfort or pain in the temporomandibular joint and its associated structures may occur. If adaptation is good, then changes occur which tend to restore the original interocclusal distance. In the first patient, adaptation occurred by depression of the posterior teeth and wear of the occlusal surfaces of the opposing teeth. When there is evidence of mandibular overclosure, this condition may be corrected so that the interocclusal distance is restored to its original value. The second patient illustrated this condition. Even though the changes which lead to mandibular overclosure occur gradually over many years, patients' responses to a sudden restoration to the correct occlusal face height can vary widely. If such changes are contemplated, the patient's response to them must be tested before permanent prostheses are constructed.     

An investigation into the origin and nature of 'amyloid' in a calcifying epithelial odontogenic tumour

Fresh and fixed tissue from a resection specimen of a calcifying epithelial odontogenic tumour (CEOT) was prepared for histological, histochemical, immunological and biochemical investigation in order to study the nature of the amyloid-like material. The fixed tissue gave positive reactions with Congo-red, Thioflavin T and the dimethylamino benzene (DMAB)-method for tryptophan. The diazotization-coupling (DC) method for tyrosine was negative. The major protein purified from the unfixed tissue by sequential gel filtration had a molecular weight of 9,800. The amino acid analysis of this protein had similarities with tuft enamel protein, immune amyloid and the variable light chain component (VK). From the data obtained in this study, it is not possible to determine the precise nature of the amyloid-like material in this CEOT. However, the results do support the concept that 'amyloid' should be considered as a term describing a broad group of related proteins.     

Fabrication of removable stone dies using cemented dowel pins.

Proper dowel pin placement in the working cast is important in the fabrication of a cast restoration. A technique is suggested whereby the dowel pin is orientated and cemented after the working cast has been separated from the impression. This procedure produces a working die that has a correctly positioned dowel pin, is stable, and can be repeatedly returned to its original relationship. A technique is suggested whereby the dowel pin is orientated and cemented after the working cast has been separated from the impression. This procedure produces a working die that has a correctly positioned dowel pin, is stable, and can be repeatedly returned to its original relationship.     

An evaluation of microdisks for dental identification

Twenty polyester dental identification microdisks were bonded to the surface of 20 extracted human mandibular molars and placed in 0.9% saline solution for 26 weeks, after which the teeth with bonded microdisks were embedded in bovine muscle tissue and incinerated for 11 minutes. Under the conditions of this study, 2 of the 20 polyester microdisks did not demonstrate deterioration and remained legible after storage in saline. The teeth and bonded microdisks did not appear to be affected by 11 minutes of incineration. A list of ideal characteristics for identification microdisks did proposed.     

Oral complications associated with neonatal oral tracheal intubation: a critical review

This paper summarizes and evaluates the oral complications associated with orotracheal intubation in neonates. The palatal defect resulting from orotracheal intubation is best described as palatal grooving, rather than clefting since no oral nasal communication has been demonstrated. Palatal grooving may be caused by the inhibition of the molding tongue forces on the lateral palatine shelves. The incidence of palatal grooving increases with duration of intubation and reportedly resolves following extubation. However, posterior cross-bites, high palatal vaults, and poor speech intelligibility have been reported in children who previously have been intubated. Impingement of an orotracheal tube on the alveolus rather than on the palate may cause alveolar grooving which can cause dilaceration of primary teeth. Bilateral linear enamel hypoplasia in premature neonates is caused by an interruption in amelogenesis from intrauterine disturbances. However, gross unilateral incisal enamel hypoplasia in children who have been intubated is probably due to traumatic intubation. Avoiding excessive pressure on the maxillary alveolus during intubation is suggested. An appliance is available which secures oral tubes and protects the palate and alveolus.