Peripheral nerve response to injury

Oral and maxillofacial surgeons caring for patients who have sustained a nerve injury to a branch of the peripheral trigeminal nerve must possess a basic understanding of the response of the peripheral nerves to trauma. The series of events that subsequently take place are largely dependent on the injury type and severity. Regeneration of the peripheral nerve is possible in many instances and future manipulation of the regenerative microenvironment will lead to advances in the management of these difficult injuries.     

Risk factors for diagnostic subgroups of painful temporomandibular disorders (TMD)

Temporomandibular Disorders (TMD) encompass several entities, which may have differing etiologies. To test this hypothesis, we investigated risk factors for three diagnostic subgroups of painful TMD. Ninety-seven subjects with myofascial pain only, 20 with arthralgia only, 157 with both myofascial pain and arthralgia, and 195 controls without TMD pain met criteria for study eligibility. Investigated risk factors included both physical and psychological variables. Adjusted odds ratios were calculated by multiple logistic regression analyses. Myofascial pain occurring alone was significantly associated with trauma (Odds Ratio [OR] = 2.0), clenching (OR = 4.8), third molar removal (OR = 3.2), somatization (OR = 3.7), and female gender (OR = 4.2). Myofascial pain with arthralgia was significantly associated with trauma (OR = 2.1), clenching (OR = 3.3), third molar removal (OR = 4.0), somatization (OR = 5.1), and female gender (OR = 4.7). No significant associations were found for the small-arthralgia-only group.     

The gingival immune response to Actinobacillus actinomycetemcomitans in juvenile periodontitis.

The established and advanced lesions of juvenile periodontitis-localized form (JP) are predominated by B-lymphocytes and plasma cells. Local immune processes may participate in protective or immunopathologic roles in the pathogenesis of this disease. Actinobacillus actinomycetemcomitans (A.a.) is implicated as a primary etiologic agent in JP. An in vitro gingival explant culture system was utilized to study the specificity of immunoglobulins produced by diseased JP tissues. A dot-immunobinding assay demonstrated that 46% of the supernatant fluids (SF) from explant cultures of diseased tissues (n = 39) were positive for the presence of antibody to A.a. Y4, while 61% of autologous JP sera (n = 39) tested positive. For rapidly progressive (RP) and adult periodontitis (AP) SF, 50% and 40% were positive for A.a. Y4, respectively. Seventeen percent of SF from healthy tissue were positive for A.a. Y4. There was no significant difference between JP SF reactivities to A.a. Y4 when compared to reactivities of SF from AP and RP patients. Only 10% of JP SF were positive for Porphyromonas asaccharolytica, a non-oral control microorganism. The de novo biosynthesis of antibody in JP tissue, reactive with A.a. Y4, was demonstrated with Staph Protein A isolated 14C-labeled IgG (SPAG) and the use of a dot-immunobinding assay and autoradiography. The in vitro gingival tissue explant culture system described provides a useful model for the study of the synthesis and specificity of localized immunoglobulins produced by diseased tissues of JP patients.     

The effect of dentine conditioning with polyacrylic acid on the clinical performance of glass ionomer cement — 3-year results

Forty cervical abrasion lesions were restored with a self-cure Type 2A glass ionomer cement. Prior to placement of the restorations, 20 lesions were scrubbed for 15 seconds with 25 per cent polyacrylic acid and 20 lesions were cleaned with a pumice and water slurry on a rubber cup. After three years, there was negligible marginal staining, and one restoration from each group was partly lost. There was no evidence to suggest that polyacrylic acid was preferred to pumice and water in the restoration of cervical abrasion lesions with glass ionomer cement.     

Colour stability of composite resins: A clinical comparison

Ninety three Class III cavities were prepared in 66 patients, and restored with one of three resin-based restorative materials; a hybrid self-cure material, a microfine self-cure material, or a microfine light-cure material. Standard sets of clinical colour transparencies were used to evaluate colour match with the surrounding tooth and marginal discoloration over five years. After five years, all materials had become slightly darker, the microfine self-cure material significantly more so than the light-cure material. There was no significant development of marginal discoloration.     

Cariostatic effect of glass ionomer cement: a five-year clinical study

Composite resin and glass ionomer cement were used to restore 67 and 65 Class V carious lesions, respectively. The restorations were assessed each year for recurrent caries and marginal staining. After five years, 1 per cent of glass ionomer and 6 per cent of composite restorations had become carious, and there was approximately twice as much marginal staining around the composite as around the glass ionomers. There appear to be significant benefits in using glass ionomer to restore Class V carious lesions.     

Effect of carbamide peroxide and hydrogen peroxide on enamel surface: an in vitro study

The aim of the study was to investigate changes in the micromorphologyl and microhardness of the enamel surface after bleaching with two different concentrations of hydrogen peroxide (HP) and carbamide peroxide (CP). Bovine enamel samples were embedded in resin blocks, and polished. Specimens in the experimental groups (n = 10) were treated with bleaching gels containing 10% CP, 35% CP, 3.6% HP, and 10% HP, respectively, for 2 h every second day over a period of 2 weeks. The gels had the identical composition and pH and differed only in their HP or CP content. The roughness and morphology of the enamel surface were analyzed using laser profilometry and SEM. Microhardness was measured using a Knoop hardness tester. The data were evaluated statistically. Specimens in the 10% HP group showed significantly higher roughness after bleaching compared to the control group (ΔRa, p = 0.01). Bleaching with 35% CP showed only a tendency to increase roughness (ΔRa, p = 0.06). Application of 10% CP or 3.6% HP had no significant influence on Ra. Enamel microhardness was significantly higher after application of 10% HP compared to the control (ΔMic = 8 KHN, p = 0.0002) and 35% CP (ΔMic = 20KHN, p = 0.01) groups. In summary, application of CP and HP showed only small quantitative and qualitative differences. In addition, the influence of bleaching procedure on the morphology and hardness of the enamel surface depended on the concentration of the active ingredients.     

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.