Assessment of wear characteristics, longevity and stiffness of Essix-type retainers.

OBJECTIVE: To compare four commercially available Essix-type retainers in terms of longevity, wear characteristics, stiffness and their range of rigidity. MATERIALS AND METHODS: An in vitro study was conducted at Queen Mary University of London. Four groups of thermoplastic materials were included: Duran (PETG), Essix C + (Polypropylene), Vivera and Zendura (Polyurethane). A working typodont was fabricated to evaluate surface wear characteristics using a wear machine with a customized jig. Retainers were measured for tensile test, and water absorption was measured at five different time points up to 6 months after initial immersion in two different physical states and two different solutions. Hydrolytic degradation was also evaluated using FTIR spectroscopy. RESULTS: Essix C + was the most flexible retainer with Vivera the stiffest material. Zendura and Essix C + had the most surface wear (413 µm ± 80 and 652 µm ± 12, respectively) with absorption rates of up to 15 wt% in artificial saliva occurring with Zendura. Only Essix C + displayed signs of degradation following water absorption. CONCLUSIONS: All materials had characteristic levels of flexibility and were susceptible to water absorption. Duran 1.5 mm performed similarly to Vivera in relation to stiffness and wear properties. While Zendura and Vivera have similar chemical structures, they exhibited differences concerning wear resistance and water absorption. Further clinical research evaluating the clinical relevance of these laboratory findings is required. CLINICAL RELEVANCE: Characteristic patterns of wear and rigidity of four commercially available Essix-type retainers were observed. This information should help in the tailoring of retainer material on a case-by-case basis considering treatment-related factors and patient characteristics including parafunctional habits.

Prevalence of impacted third molars and the reason for extraction in Saudi Arabia.

PURPOSE: This study aims to record the current pattern of third molar impactions and relevant reasons for extraction in Riyadh, Saudi Arabia. We hypothesized that the principal reason for extraction was elective. MATERIAL AND METHODS: Orthopantomograms (OPG) radiographs and electronic files relating to 4000 patients were retrospectively collected from patients between the ages of 21 and 50 years old. Of these, 1014 were included in this study (514 females, 500 males). The classification was determined according to the Winter, Pell, and Gregory classification. The analysis was done using the chi-square (χ2) test, with SPSS version 25 (IBM, Inc, Chicago, IL). A p-value of < 0.05 was considered statistically significant. RESULTS: A total of 2240 impacted third molars were found with no gender predilection. Impaction was more commonly found in the mandible (58.5%) than the maxilla (41.5%). The most common reason for extraction was 'asymptomatic; prophylactic indication' (66.8%), followed by 'symptomatic' (33.2%). Vertical angulation was most common in the maxilla (56.5%), and mesioangular impaction in the mandible (40.5%). CONCLUSION: There is a high rate of third molar impaction in the central region of Saudi Arabia. It is more likely to occur in the mandible than the maxilla with no gender predilection. The majority of the patients were referred for elective asymptomatic reasons. Mesio-angular impaction is mostly found in the mandible and vertical angulation in the maxilla. Both arches had a C level depth and Class I Ramus relationship. Further studies should be conducted with the wider Kingdom of Saudi Arabia so that the population can be more accurately represented.

Reconstruction of Thin and Pliable Oral Mucosa After Wide Excision of Oral Cancer Using a Trimmed Anterolateral Thigh Free Flap as an Adipofascial Flap.

A 21-year-old female patient underwent wide excision of the buccal mucosa and tongue as well as selective neck dissection due to squamous cell carcinoma on the left side of the tongue. She had a severe limitation in opening her mouth, owing to fibrosis of the mucosa and scar contracture after adjuvant radiation therapy. Reconstruction of the oral mucosa and tongue defect was performed after removal of the scar to improve mouth opening. An anterolateral thigh (ALT) flap was used, trimmed to an adipofascial flap for the reconstruction of the thin and pliable oral mucosa and tongue. The maximum mouth opening improved to 40 mm intraoperatively and was 30 mm after surgery. The adipofascial ALT flap had excellent viability and presented neomucosa after secondary healing. An adipofascial flap obtained by trimming an ALT flap could be a reliable option for the reconstruction of thin and pliable oral mucosa after wide excision of oral cancer.