Neutral zone or conventional mandibular complete dentures: a randomised crossover trial comparing oral health-related quality of life

There is widespread consensus that the neutral zone (NZ) concept contributes to improved stability for mandibular complete dentures (CDs). However, little is known about its impact on oral health-related quality of life (OHRQoL) of edentulous patients compared to conventionally (CV) manufactured dentures. In this prospective crossover trial, performed at the Oral Health Centre of the University of the Western Cape, CV and NZ mandibular dentures were made for each patient. Scores from the 20-item oral health impact profile (OHIP-20) for both types of dentures were compared with pre-treatment scores using paired t-tests. Treatment effect size (ES) was established. Associations of OHIP-20 scores and several patient variables (age, gender, period of edentulousness, quality of the denture-bearing tissue, denture dimensions, reference) were performed using the generalised linear model. Significance was set at P = 0 05. Records of thirty-five participants were included in the study (mean age of 62 3 years, range 47–85 years). There were highly significant differences between pre-treatment and both posttreatment OHIP-20 scores with t = 6 470 for CV and t = 6 713 for NZ. Treatment ES was large for both types of dentures (>0 8). difference of ES between NZ and CV dentures was small (ES < 0 2). None of the patient variables showed significant associations with OHIP-20 scores of the two types of dentures, except for preference and NZ OHIP-20 scores. For this group of patients, both treatment methods improved OHRQoL significantly and patientrelated factors did not influence impact on OHRQoL differently for both interventions.University of the Western Cap

The use of light-cured acrylic resin for custom trays by undergraduate dental students: A survey

Presented at IADR 2005 – Kuwait (1st African Middle-Eastern IADR Conference)This study aims to evaluate the acceptance of light-cured acrylic resin for custom trays by dental students. A questionnaire addressing the use and handling properties of both light-cured (Megatray, Megadent, Germany) and chemically-cured (Excel, Wright Health Group, UK) custom tray materials was distributed amongst undergraduate dental students of the University of the Western Cape. Of a total of 196 dental students, 38 were absent on the day of the survey. Of the 158 questionnaires that were distributed and returned, 18 did not meet the inclusion criteria and 1 person chose not to participate. Of the 139 participating students, 98 were in 4th year, 41 in 5th year. With regards to the light-cured acrylic custom tray material, 77% used it most often, 64% said it saved time and 62 % said that it was easier to handle. Fifty two percent indicated that both types of materials should be taught in undergraduate training, 26% preferred the light-cured acrylic resin custom tray material, 20% suggested that only the light-cured resin be used and no one suggested the chemically-cured resin exclusively. The study concluded that most undergraduate students positively accepted the light-cured resin, but training in the use of both materials was recommended

Aesthetic clasp design for removable partial dentures: A literature review

Removable partial dentures (RPD) are an effective and affordable treatment option for partial edentulism. If the main reason for seeking treatment is the need for improved aesthetics, treatment should be geared towards achieving this goal. This article is the result of a literature study on aesthetic clasp design for the conventional RPD. In this context, the position of the clasp on the tooth, clasp types, clasp material and alternative methods of retention are reviewed. Although published in reputable journals, the authors report that many articles published on this subject are of a descriptive nature and lack scientific evidence. Therefore, clinicians are encouraged to be critical in their interpretation of literature and the application of published information in their clinical practices

Temperature changes along a dental implant

AIMS: The aims of this in vitro study were to analyse temperature changes along the surface of a dental implant and to establish the abutment temperature that could cause the critical 47ºC/1min threshold at implant level. METHODS: Eight thermocouples were attached at 1 mm intervals to an abutment/implant configuration. The model consisted of 2 compartments in a thermostatically controlled environment. The upper compartment represented the oral cavity with the abutment, which was exposed to 20ml of hot water. The temperature at each thermocouple was logged over a period of 10 minutes. A Spearmans Rank correlation test and logistic regression model were used for the statistical analysis of the time/temperature databases and the estimation of the ‘effective dose 50’ for the abutment (95% confidence interval). RESULTS: For 53 test series, the abutment temperature ranged from 52.80ºC to 71.72ºC. There was a positive correlation between the maximum temperature at implant level and the temperature of the abutment. The 47ºC/1min threshold was reached 31 times at the most cervical implant level and decreased in frequency further away from the heat source (14, 6, 3, 1 and 1 times resp.) The ED50 was estimated at 62.3ºC. This means that for an abutment temperature of 62.3ºC there was a 50% chance that 47ºC for 1 minute at implant level would be reached. CONCLUSION: This in vitro study supports the hypothesis that abutment temperature is transmitted to an implant. Although results of in vitro studies should be interpreted with caution, clinicians should be aware of temperature changes along implants and the potential risk associated with it.Web of Scienc

Determining the Dimensional Stability, Fracture Toughness and Flexural Strength of Light-cured Acrylic Resin Custom Tray Material

N/ALight-cured acrylic resin custom tray material is used in commercial dental laboratories but little evidence- based scientific information on its physical properties is available. Objectives: This study investigates the dimensional stability of light-cured acrylic resin custom tray material and compares its fracture toughness and flexural strength to a chemically-cured acrylic material. Method: For dimensional stability, 20 light-cured specimens were fabricated and measured 3 times at regular time intervals over 48 hours. Mean shrinkage was calculated for each time interval and the mean values were compared to the standard using the Wilcoxon Rank Sum test. A p-value of <0.05 was considered significant. For fracture toughness, 2 groups of 20 light-cured and chemically-cured acrylic materials with a single-edge notch were subjected to a compressive load using the 3-point bending technique. For flexural strength, 1 group (n=20) of each material was subjected to a compressive load using 3-point bending. The highest load before failure was used to calculate the fracture toughness and flexural strength. Differences in fracture toughness and flexural strength values between the 2 groups were compared using ANOVA testing. A p-value of <0.05 was considered significant. The chemically-cured group was accepted as the control group. Results: Compared to the standard, shrinkage was significant for all time intervals (p<0.05). The difference in shrinkage among time intervals was not significant (p>0.05). The fracture toughness and flexural strength were significantly higher for the light-cured material. Conclusions: Trays made from light-cured acrylic resin can be used immediately following polymerization. The light-cured material is more resistant to bending and crack propagation than the chemically-cured type.Megadent for donating materials

The impact of new complete dentures on oral health-related quality of life

OBJECTIVE: To investigate the relationship between complete dentures and oral health-related quality of life (OHRQol). METHOD: Seventy-six patients were conveniently selected from the waiting list for complete dentures. At the first visit (pre-treatment) the patients were interviewed using the Ora Health Impact Profile for Edentulous Patients (OHIP-EDENT). Sixty-three of these patients were interviewed telephonically 2 to 3 months after receiving their new complete dentures (post-treatment). RESULTS: Mean domain scores were significantly lower post­ treatment for psychological discomfort and disability, social disability and handicap. CONCLUSION:This study shows that after the provision of a new set of complete dentures the OHRQoL of patients im­proved significantly on four of the seven domains for the first 2 to 3 months post-insertion.Department of HE and Training approved lis

The effect of different reinforcements on the fracture toughness of materials for interim restorations

STATEMENT OF PROBLEM. Fracture of an interim fixed partial denture (FPD) may jeopardize the success of the interim prosthodontic treatment phase and cause patient discomfort. PURPOSE. The purpose of this study was to compare the fracture toughness of a polymethyl methacrylate (PMMA) resin and a bis-acryl composite (BAC) resin reinforced with stainless steel wire, glass, and polyethylene fiber. MATERIAL AND METHODS. Four groups (n=13) of each of the 2 materials were prepared for the single-edge 3-point-bending test. Three groups had the different reinforcements, and the group without reinforcement served as control. Using a universal testing machine, peak load to fracture was recorded and fracture toughness (KIC) was calculated in MNm-1.5. Median KIC values were compared by means of nonparametric ANOVA (Kruskal-Wallis test, α=.05). RESULTs. For the controls, the fracture toughness for PMMA resin (KIC=27.9) was significantly lower (P.10, for BAC resin and KIC=25.8, P>.10, for PMMA resin). There was no significant difference between the fracture toughness of the wire and glass fiber reinforcements for both interim materials (P>.10 in both instances). CONCLUSIONS. Of the 3 reinforcement methods evaluated, wire and glass fiber reinforced the PMMA and BAC resin materials best.Web of Scienc

Perceptions of academic staff about mentoring in a Faculty of Dentistry in a public university in South Africa

Mentoring programs contribute to the development and retention of academics in dental education. To describe the perceptions of academic staff of the Faculty of Dentistry, University of the Western Cape, South Africa, about a funded pilot mentoring process. Cross-sectional, purposive sampling qualitative design. Twenty mentees who had engaged in the funded mentoring process were targeted for semi-structured interviews, to describe their perceptions about the ongoing mentorship process, experiences in other mentoring processes, and expectations about future formal mentoring in the faculty. Quantitative data was analysed descriptively, while content analysis of the qualitative data was performed to identify themes. Perceptions of eight mentees, aged 37 to 59 years and spent between 3 and over 20 years in the faculty, were categorized into two themes - ‘A welcome initiative’ and ‘Mentorship seen as a holistic experience’. The program provided the much-needed space where mentees felt they could seek guidance for their development. Expectations from a future formal program included assistance in meeting institutional and personal demands. Participants’ expectations were broader than what the pilot program offered, thoug

Conformity of removable partial denture designs to agreed principles based on materials used - A preliminary study

Removable partial denture (RPD) designs may differ based on types of materials used. The aim of the study was to investigate how a sample of non-metal clasp (NMC), acrylic and metal RPD designs complied with biomechanical design principles. This cross-sectional study examined 60 clinical designs of NMC, acrylic and metal RPDs at 3 commercial dental laboratories in the Cape Town Metropole, at the stage when the dentures were ready for transport to dentists

Comparing patient-based outcomes related to neutral zone and conventional mandibular dentures: A systematic review

Neutral zone mandibular dentures are considered tobe superior to conventional complete dentures.Conventional complete dentures (CD) have been the most common and only treatment modality for rehabilitation of edentulousness until the introduction of dental implants. Implant-retained or implant-supported prostheses have been proven to be superior to conventional CDs in terms of patient-based outcomes (PBOs).' However, implant therapy may be out of reach of patients due to a variety of reasons