MATERIALS AND METHODS: This is an in vitro study using two extracted sound human mandibular molars. One tooth was prepared to receive the metal onlays and another one for the RNC onlays which were fabricated using the computer-aided design and computer-aided manufacturing (CAD/CAM) technology. Twelve metals and 12 ceramic onlays were fabricated before they were placed at their respective preparation and examined under the Leica stereomicroscope, M125C (Leica Microsystems, Wetzlar, Germany) for a marginal analysis. The gap width was measured at 10 predefined landmarks which included 3 points on the buccal and lingual surfaces each and 2 points each on the mesial and distal surfaces, respectively.
STATISTICAL ANALYSIS: Mann-Whitney post hoc test was used for statistical analysis (P ≤ 0.05).
RESULTS: Overall, the RNC onlays showed significant lower marginal gap with the exception of the landmarks 5 and 6 (on distolingual) and no significant difference at landmark 7 (on midlingual). It was observed that the marginal gap were all within the clinically acceptable limit of 120 μm.
CONCLUSIONS: Based on the results obtained, it can be concluded that the RNC CAD/CAM onlays are a promising alternative to the metal onlays.
Objective: This study aimed to determine the prevalence of third molar impaction and related pathologic conditions in a cohort of patients living in North-eastern Peninsular Malaysia.
Methods: In this retrospective study, 490 orthopantomograms (OPGs) of patients who were referred to the Oral and Maxillofacial Surgery department between January 2010 and December 2019 were assessed. Data including age, gender, ethnicity, frequency of third molar impactions, their angulations and levels of eruption, retromolar space, and associated pathologic conditions were collected. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) version 24.0. The significance level was set to P < 0.05.
Results: A total of 490 patients with a mean age of 28.87 years (range: 20-64) demonstrated 1957 impacted third molars (1022 mandibular + 935 maxillary). Impacted third molars were more likely present in females than males (1:2.20) (p < 0.05); and in Malay-ethnic (44.49%) patients followed by Chinese (34.45%) and Indians (21.02%). Mesioangular was the most common angulation of impaction both in the maxilla (24.68%) and mandible (18.34%). The most common pattern of third molar impaction was IIA (61.67%), and the retromolar space was significantly larger in males (13.6 mm; P < 0.05) than females (11.6 mm). The most frequently occurring pathological condition associated with third molars impaction is dental caries in the second or third molar (15.38%).
Conclusions: This study highlights mesioangular impaction with their occlusal plane at the same level as the occlusal plane of the adjacent tooth being the most prevalent pattern of third molar impaction in North-eastern Peninsular Malaysia.