Dynamic shear properties of the temporomandibular joint disc

Shear stress might be an important factor associated with fatigue failure and damage of the temporomandibular joint disc. Little information, however, is available on the dynamic behavior of the disc in shear. Since the disc is an anisotropic and viscoelastic structure, in the present study the dependency of the dynamic shear behavior on the direction and frequency of loading was examined. Ten porcine discs were used for dynamic shear tests. Shear stress was applied in both anteroposterior (A-P test) and mediolateral (M-L test) directions. The dynamic moduli increased as the loading frequency increased. The dynamic elasticity was significantly larger in the A-P test than in the M-L test, although the dynamic viscosity was similar in both tests. The present results suggest that non-linearities, compression/shear coupling, and intrinsic viscoelasticity affect the shear material behavior of the disc, which might have important implications for the transmission of load in the temporomandibular joint.     

Incidence of penetration of a blood vessel during inferior alveolar nerve block

Aspiration of the syringe after the needle had been placed in position for an inferior alveolar nerve block (but before the anaesthetic solution was injected) in 250 patients showed that the tip of the needle was in a blood vessel in 49 (20%). Aspiration of blood was significantly more common in patients aged 9-19 years than in all others (P=0.04).     

Oral lichen planus: a preliminary clinical study on treatment with tazarotene

OBJECTIVE: The rationale for using tazarotene in oral lichen planus (OLP) is its regulatory action on the growth and differentiation of keratinocytes and on inflammation. This randomized, placebo-controlled study addresses evaluation of the effects of topic tazarotene in the treatment of OLP. DESIGN: The degree of lesions before and after treatment scored by a 6-score scale in six cases treated with tazarotene was statistically compared with those of six controls treated with placebo. SUBJECTS: Twelve patients with hyperkeratosic OLP were randomly allocated to treatment with tazarotene gel 0.1% b.i.d. or with placebo for eight consecutive weeks. METHODS: The statistical comparison was executed by means of Wilcoxon analysis for paired data. RESULTS: Patients treated with tazarotene presented a significant reduction of their lesions as compared with the control group. Among transitory side-effects, burning sensation and taste abnormalities were observed. CONCLUSION: Topical tazarotene may be a valuable therapeutic tool in the treatment of hyperkeratotic OLP.     

Validation of a Facial Image Scale to assess child dental anxiety

Summary. Objective. To examine the validity of a scale that uses faces as an indicator of children’s dental anxiety. Setting. Department of Child Dental Health waiting room, Newcastle Dental Hospital. Subjects and methods. 100 children (aged 3–18 years) completed the Facial Image Scale (FIS) and the Venham Picture Test (VPT) in the dental hospital waiting room. Results. A strong correlation (0·7) was found between the two scales, indicating good validity for the FIS. Findings also showed that a small, but significant, number of children are anxious in the dental context. Conclusion. The findings suggest that the FIS is a valid means of assessing child dental anxiety status in a clinical context.     

Biocompatibility of nickel and cobalt dental alloys

Allergies related to dentistry generally constitute delayed hypersensitivity reactions to specific dental materials. Although true allergic hypersensitivity to dental materials is rare, certain products have definite allergenic properties. This review presents a comparative evaluation of the biocompatibility of nickel-chromium, nickel-chromium-beryllium, and cobalt-chromium alloys.     

Cementifying fibroma of the frontal bone: a case report

Cementifying fibromas are rare fibro-osseous tumours that are usually found in the jaws. We report a 10-year-old boy who presented with a mass in the frontal bone causing frontal bossing and proptosis. The preoperative diagnosis was not clear despite computed tomographic and magnetic resonance imaging. The lesion was resected completely and found to be a cementifying fibroma. It was reconstructed at the same operation and he made a good recovery with no sign of recurrence.     

Quantitative methylation analysis of resection margins and lymph nodes in oral squamous cell carcinoma

Resection is the preferred treatment for oral squamous cell carcinoma, and pathological staging of the resected specimen is crucial. The role of molecular biology in the diagnosis of minimal residual disease has not been fully investigated and may improve staging. Multiple adjacent specimens were taken from the tumour, the invasive front, the surgical margin, and the lymph nodes of 20 specimens from patients with oral cancer. Bisulphite-treated DNA from these specimens was assayed quantitatively with pyrosequencing methylation assays (PMA) of CpG islands within the gene promoters of the p16 and CYGB genes. Results were recorded with histopathological results, and compared with clinical outcome. Biological and technical replicates confirmed the reliability of the techniques. PMA upgraded 13 of the 20 surgical margins, 6 of which subsequently had a recurrent tumour. Not all of these recurrences were predicted and the effects of adjuvant treatment make firm conclusions difficult.     

Effects of child formula dentifrices on artificial caries like lesions using in vitro pH-cycling: preliminary results

AIM: To compare the remineralisation effects of different child dentifrices on primary teeth. DESIGN: In vitro single-section technique and pH-cycling model. METHODS: Primary teeth were painted with nail varnish, leaving a 1 mm wide window before placing in demineralising solution for 96hr to produce artificial carious lesions 150-200 microm deep. Teeth were longitudinally cut into approximately 100-150 microm thick sections and assigned to three groups (n = 7). Sections in Group A were exposed to Perioe Children's Toothpaste (LG, Korea), Group B to Colgate Pokemon (Colgate-Palmolive, Thailand) and Group C to Vicco (Vicco Laboratories, India). Polarised light microscopy and microradiography was used to evaluate lesion depth, before and after 7 days pH cycle. RESULTS: Mean lesion depths in Groups A and C increased by 11% and 14% respectively, while Group B demonstrated a lesion reduction of 3%. Comparisons using ANOVA and Student-Newman-Keuls tests showed that Groups A and C were significantly different from Group B (p < 0.05), but there was no significant difference between Groups A and C. CONCLUSIONS: Based on the data obtained, Colgate Pokemon remineralised initial carious lesions. In addition, when compared to Colgate Pokemon, Perioe Children's Toothpaste failed to show 'healing' efficacy even though it is claimed to contain fluoride.