Effects of clinical local factors on thickness and morphology of Schneiderian membrane: A retrospective clinical study.

BACKGROUND: It was informed that the thickness of maxillary sinus membrane may be affected by the local and patient-related factors in the literature. PURPOSE: The aim of this retrospective study is to evaluate factors that may have an influence of the thickness and morphology of the maxillary sinus membrane. MATERIALS AND METHODS: A total of 414 cone beam computed tomography images of 207 patients were evaluated. Radiographic parameters were evaluated at each maxillary premolar and molar tooth regions. Statistical analysis was performed to assess the association between the maxillary sinus mucosa thickness and morphology. The following factors including gender, periodontal bone loss (PBL), bone density, amount of residual alveolar bone at the edentulous space, vitality of the teeth present, and anatomical relationship between the sinus floor and posterior teeth were evaluated. RESULTS: The mean thickness of maxillary sinus membrane ranged between 1.47 to 2.92 mm and was significantly thicker in male subjects (P < .05). Positive correlation was detected between the sinus membrane thickness values in each posterior tooth region (P < .05). Thickening of the membrane was noted in 53% of the scans. The most commonly observed morphological change was flat thickening of the membrane (21%). No correlation was found between the evaluated local factors on the thickness and morphology of the maxillary sinus membrane (P > .05). CONCLUSIONS: Tooth vitality, residual alveolar bone height, and PBL seem to have no effect on the thickness and morphology of the maxillary sinus membrane.

Effects of Different Levels of Restraint Stress on Bone-Implant Contact.

This study examined the effects of different levels of chronic restraint stress on bone-titanium implant contact in rats. This study included 32 adult female Sprague-Dawley rats. The machined surface titanium implants were surgically placed into the metaphyseal region of the rat tibias. Next, the rats were divided randomly into 4 groups, namely, control (CNT) (n = 8), low-restraint stress (LRS) (n = 8), medium-restraint stress (MRS) (n = 8), and high-restraint stress (HRS) (n = 8) groups. The rats in the CNT group received only the titanium implants surgically but did not receive any further treatment during the experimental period of 30 days. The rats in the LRS, MRS, and HRS groups were applied restraint stress for 1, 2, and 4 hours, respectively, daily for 28 days starting from day 2 after the surgery. At the end of the study period, the rats were sacrificed and their implants and the surrounding bone tissues were harvested for performing nondecalcified histological analysis. Moreover, blood samples were collected from the rats and were centrifuged for analyzing serum cortisol levels. Serum cortisol levels of the rats in the LRS, MRS, and HRS groups were higher than those of the rats in the CNT group (P < 0.05). Moreover, serum cortisol levels of the rats in the HRS group were higher than those of the rats in the MRS and LRS groups (P < 0.05). The extent of bone-implant contact was lower in the rats in the HRS group than in the rats in the CNT and LRS groups (P < 0.05). These data suggest that the application of 4-hour chronic restraint stress during the 28-day experimental period impaired the bone-implant contact.