Exfoliative cytology in clinical oral pathology

Exfoliative cytology is a rapid, non-invasive procedure for assessing dysplastic change within the oral epithelium. The indications for oral exfoliative cytology are reviewed and a technique for cell collection and smear examination is presented. The value of exfoliative cytology in oral cancer screening programmes as a public health measure is discussed.     

Accuracy of four types of rubber impression materials compared with time of pour and a repeat pour of models

The accuracy of four types of elastomeric impression materials was studied as a function of model location, time of pouring, and repetition of pouring. There was little change in dimension among abutment preparations for all materials, for all times of pour, and with a repeat pouring. It appears that measurements between posts are not sensitive to detecting differences between materials and that other dimensions should be examined to discern where differences might lie. The diameter of the stone post was larger than the standard for the AS and PS materials and was unchanged or smaller than the standard for the CS and the PE. The vertical dimensions of stone posts were, in general, shorter than the standard for all materials, with the AS demonstrating the smallest change. The AS and CS products demonstrated the best recovery from undercuts and the least change in dimensions between an initial and second pour of an impression. The AS and PE were the least affected with delays of 1, 4, and 24 hours in pouring the impression.     

Cognitive and learning styles as predictors of success on the National Board Dental Examination

Using a deidentified retrospective dataset of three cohorts of matriculated dental students, we measured the degree to which selected student attributes, the Learning Type Measure, the Myers-Briggs Type Indicator, and Dental Admission Test subtests scores predicted passage on the National Board Dental Examination (NBDE), Parts I and II. Gender, Myers-Briggs Type Indicators, and the Dental Admission Test subtests for academic average and biology were found to be predictive of passing the NBDE Part I. Gender, a Myers-Briggs Type Indicator (thinking over feeling), and the Dental Admission Test subtests on reading and biology were found to be predictive of passing the NBDE Part II. The Learning Type Measure was not found to be predictive of passing the NBDE Part I or Part II. This study holds implications for heightening faculty members' awareness of students' aptitude and cognitive attributes, for teaching, and for the admissions process.     

Synergistic enhancement of collagenous protein synthesis by human gingival fibroblasts exposed to nifedipine and TNF-alpha in vitro

BACKGROUND: Gingival overgrowth occurs in patients receiving nifedipine. Gingival inflammation may be an etiologic factor. METHODS: Gingival fibroblasts were either exposed to (i) 0-500 ng/ml TNF-alpha or 10(-7) M nifedipine or (ii) 0-500 ng/ml TNF-alpha + 10(-7) M nifedipine for 7 days. 3H-proline was used to quantify collagenous protein synthesis. RESULTS: Both TNF-alpha and 10(-7) M nifedipine significantly decreased cell proliferation, and 10(-7) M nifedipine + 500 ng/ml TNF-alpha reversed these effects. Collagenous protein synthesis was significantly reduced by TNF-alpha and was significantly enhanced by either 10(-7) M nifedipine or 5-500 ng/ml TNF-alpha + 10(-7) M nifedipine. CONCLUSIONS: Our data report that nifedipine reverses the primary effects of TNF-alpha on collagenous protein synthesis. Patients with gingivitis could be susceptible to gingival overgrowth during nifedipine therapy as a result of synergistic effects of these agents on fibroblast metabolism, which occurs irrespective of reduced cell numbers.     

Dentoalveolar relations in children born with a unilateral cleft lip and palate (UCLP) in Western Australia.

OBJECTIVE: Our objective was to evaluate complete unilateral cleft lip and palate repair outcome in the Cleft Unit in Perth, Western Australia, by assessment of dentoalveolar relationships. DESIGN: This is a retrospective study. SETTING: Our subjects were individuals under the care of the cleft team in Perth, Western Australia. PARTICIPANTS: All patients with unilateral cleft lip and palate and available 6-year casts who had been born since January 1, 1985, were identified from the cleft unit's database. The nature of the cleft was verified by examination of birth study models and photographs. A total of 54 such patients were identified. MAIN OUTCOME MEASURES: Main outcome measures were identified through dental arch relationship grading of study models using the 5 Year Old Study Model Index. RESULTS: Interexaminer and intraexaminer agreement kappa statistics revealed good to very good agreement using this index. The results indicate that the surgical outcome was graded as excellent, good, or fair for 77% of patients and poor or very poor for 23% of patients. CONCLUSIONS: The results of the Western Australia study compare favorably to the overall U.K. outcome (the Clinical Standards Advisory Group study) but unfavorably to the results of some European centers, such as Oslo.     

Step-wise analysis of the dental implant insertion process using the finite element technique

OBJECTIVES: Using the finite element method (FEM), the insertion process of a dental implant into a section of the human mandible is analysed. The ultimate aim of this article is to advance the use of an innovative engineering approach in dental practices, especially in the process of dental implantation. MATERIAL AND METHODS: The FEM and analysis techniques are used to replicate and evaluate the stress profile created within the mandible during the implantation process. RESULTS: The von Mises stress profiles in both cancellous and cortical bone are examined during implant insertion. The applied torque and the insertion stage are found to strongly influence the resulting stress profile within the surrounding jawbone. CONCLUSIONS: Through the combination of both dental and engineering expertise, a simplified and efficient modelling technique is developed. This improves the understanding of the biomechanical reaction that the jawbone exhibits due to the insertion of implant. The current research is a pilot study using the FEM to model and simulate the dental implantation process. The assumptions made in the modelling and simulation process are: (1) the implantation process is simulated as a step-wise process instead of a continuous process; (2) the implant is parallel threaded and the implant does not rotate during insertion into the jawbone. Although the modelling and simulation techniques had to be simplified, a significant amount of information is gained that helps lay a good foundation for future research. Recommendations for future studies include the variation of the torque applied during the implantation process and upgrading the software capabilities to simulate the full dynamical process of implantation.