A proposed classification for heritable human dentine defects with a description of a new entity

A newly recognized heritable dentine defect is described which is manifested as an amber, translucent colouration and total pulpal obliteration in all primary teeth. Permanent teeth have a thistle-tube pulp configuration with ubiquitous pulp stones and normal colouration.The unusual finding of true denticles in these heritable dentine defects may represent the induction of odontoblastic differentiation by aberrant epigenetic factors produced in the abnormally developing dentine.A classification for the heritable dentine defects is proposed which consists of two distinguishable groups; the dentine dysplasias and the dentinogenesis imperfectas.     

The use of the splint bar in conjunction with removable partial denture treatment

The use of a bar, joined to lone-standing abutment teeth, that spans an edentulous space is an important treatment option for many partially edentulous situations. The splint bar provides positive vertical support for the removable partial denture while rigidly splinting the abutment teeth. This article defines the situations in which this treatment should be considered and describes the technique to achieve a successful result.     

Three-year clinical evaluation of a self-cured posterior composite resin

A study was conducted to determine whether the wear resistance of a posterior composite could be improved by maximizing filler particle-to-particle contacts. This was expected to reduce stress concentrations on the resin matrix and thus reduce occlusal wear. A self-curing quartz-filled composite with this design, P-10, was used to restore 90 Class I and II cavity preparations in adult teeth. Restorations were recalled after baseline at six months, one year, two years, and three years to measure wear by direct and indirect evaluation methods. There was no apparent advantage for this material compared with other previously evaluated posterior composites. The average cumulative wear for P-10 after three years was 145 microns. In addition, the restorations were evaluated for color-matching, interfacial staining, secondary caries, marginal adaptation, surface texture, and postoperative sensitivity. This material was not significantly different in those ways from other posterior composite products except in terms of more rapid color change, because it is self-cured.     

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.     

The use of human gingival fibroblasts in culture for studying the effects of phenytoin on testosterone metabolism

In initial experiments, monolayer cultures of human gingival fibroblasts from healthy male and female subjects were incubated for various time intervals with [4-14C]-testosterone. This was rapidly taken up by the cells to reach 1.8 fmol/50,000 cells by 2 h. At 6, 12 and 24 h, the values were considerably lower (0.1-0.2 fmol/50,000 cells). In order to maintain a sufficient intracellular concentration of testosterone, unlabelled testosterone was incubated in the presence of [14C]-testosterone. This gave optimum yields of metabolites, which were separated by thin-layer chromatography and provisionally identified by comparison of their mobilities with those of authentic steroids. Final characterization of 5 alpha-dihydrotestosterone was achieved by combined capillary gas chromatography-mass spectrometry. The metabolites of testosterone were 5 alpha-dihydrotestosterone (5 alpha-DHT), 4-androstenedione, 5 alpha-androstanedione and 5 alpha-androstanediols, but the quantities formed varied with different cell lines. A similar pattern of metabolites was noted for minced human gingival tissue. Low concentrations of phenytoin generally increased the production of 5 alpha-DHT and 4-androstendione but there were marked variations between individual cell lines with regard to the magnitude of stimulation. Higher concentrations of phenytoin generally caused inhibition of steroid formation but the concentration required for this again varied with different cell lines. Thus human gingival fibroblasts in culture provide a suitable model for the study of testosterone metabolism and of the effects of drugs such as phenytoin. Variation in these effects may be reflected in individual susceptibility to phenytoin-induced gingival overgrowth.     

Early oral changes following bone marrow transplantation

This study assessed and analyzed the early oral changes following chemoradiotherapy and bone marrow transplantation. The most notable changes involved mucosal color (white and red), atrophy, vascularity, ulceration, increased salivary viscosity and xerostomia, and the patients' subjective complaints of dryness and oral pain. The ventral tongue, buccal and labial mucosa, and marginal gingiva manifested the most notable changes, while the palate was least affected. The overall trend was for the oral changes to begin slightly before transplantation, to worsen over the first 2 weeks after transplantation, and then to resolve progressively over the remainder of the study period. These oral changes appear to result from a number of insults, including the conditioning chemoradiotherapy, posttransplant immunosuppressive chemotherapy, xerostomia, local trauma, oral infections (especially those caused by HSV), and possibly acute GVHD. Oral HSV infection and/or acute GVHD should especially be considered if the oral status markedly worsens 21 days or more after transplant.     

Proteolytic activities in the supragingival plaque of monkeys (Macaca fascicularis)

Thirteen peptidase substrates were hydrolysed by this plaque. After fasting the monkeys for 24 h, the rates of hydrolysis of N-leucyl-, N-alanyl-, N-isoleucyl- and N-tyrosyl-2-naphthylamines, glycyl-L-proline 4-nitroanilide, N alpha-benzoyl-DL-arginine-2-naphthylamine and L-leucyglycine were significantly increased. Changes in these peptidase activities may serve to enhance the mobilization of amino acids and peptides, and they may explain why the growth rates of dental-plaque bacteria in vivo are generally unaffected by the availability of the host's diet.