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Evaluation of the Breakage Process of Absorbable Plates After Bilateral Sagittal Split Ramus Osteotomy Using 3-Dimensional Computed Tomography

2024-12-31T15:00:00Z

Title: Evaluation of the Breakage Process of Absorbable Plates After Bilateral Sagittal Split Ramus Osteotomy Using 3-Dimensional Computed Tomography Author(s): Atsuya Ishiyama; Karen Gomi; Riku Kohara; Akinori Moroi; Young-Min Shin; Kunio Yoshizawa; Koichiro Ueki Abstract: Introduction: This study aimed to evaluate the association between maxillofacial morphology and absorbable plate breakage in patients undergoing bilateral sagittal split ramus osteotomy (BSSO). Materials and methods: A total of 67 patients (134 sides) underwent BSSO with absorbable plate and screw fixation. Maxillofacial morphologic factors were measured by using 3-dimensional (3D) computed tomography (CT) and posteroanterior and lateral cephalograms. Plate and screw coordinates, buccolingual distance between the proximal and distal mandibular segments, condylar angle, and the angles between the proximal and distal mandibular segments and the line connecting the left and right external auditory foramina were measured using 3D CT. Plate breakage was determined using 3D CT images that were taken 1 year postoperatively. Occlusal force was measured preoperatively and 1 year postoperatively. Results: The χ2 test showed that breakages were significantly more frequent in the class III group than in the class II group. The stepwise multiple regression analysis of plate breakage in 67 patients with classes II and III relation showed that the buccolingual distance between the proximal and distal mandibular segments, setback amount, and overjet were associated with plate breakage. Discussion: These findings suggest that regardless of the skeletal relation or occlusal force, a greater buccolingual distance between the proximal and distal segments immediately after surgery tends to increase the risk of absorbable plate breakage in patients undergoing bilateral sagittal split osteotomy.

Infection control-related factors associated with microbial contamination in dental unit waterlines

2024-12-31T15:00:00Z

Title: Infection control-related factors associated with microbial contamination in dental unit waterlines Author(s): Ju-Yeon Cho; Geun-Yeong Kim; Joon Sakong; Eun-Kyong Kim; Eun-Young Park Abstract: Objectives: Although dental unit waterlines (DUWLs) could harbor biofilms that pose an infection risk to patients and staff, data on infection control factors related to the microbial contamination of DUWLs in Korea remains limited. Therefore, in this study, we aimed to analyze the microbial load in DUWL according to infection control factors using a survey. Methods: In this cross-sectional study, we surveyed 58 dental institutions for characteristics (chair number, daily patient load, and accreditation status) and infection-control status (written guidelines, designated managers, monitoring, and staff training). Simultaneously, we examined the microbial contamination levels of the high-speed handpieces and three-way air-water syringes via water sampling, expressing contamination as arithmetic and geometric means (GM)±geometric standard deviation (GSD). We used the Mann-Whitney U test to compare bacterial contamination according to institutional characteristics and infection control factors (p<0.05). Results: Overall GM contamination was 1,141 and 411 CFU/mL for high-speed handpieces and syringes, respectively, exceeding the CDC guideline of ≤500 CFU/mL. We observed significant differences in microbial loads according to the institution type, unit chair count, and average patient count. Moreover, the existence of infection control guidelines revealed significant effects. Conclusions: DUWL microbial quality varied according to the clinic size and infection control program quality. Institutions with detailed guidelines, routine surveillance, and skill-based training have achieved better microbial control. Standardized guidelines and incentivized training could help reduce infection control gaps, especially in small private clinics.

Evaluation of zygomaticus major muscle and lip-closing force in orthognathic surgery: retrospective study

2024-12-31T15:00:00Z

Title: Evaluation of zygomaticus major muscle and lip-closing force in orthognathic surgery: retrospective study Author(s): Riku Kohara; Karen Gomi; Young-Min Shin; Akinori Moroi; Kunio Yoshizawa; Koichiro Ueki Abstract: Background: This study evaluated the zygomaticus major muscle and lip-closing force before and after orthognathic surgery. Sixty female patients with jaw deformities who underwent orthognathic surgery were included. Lip-closing force and computed tomography (CT) assessments were conducted preoperatively and 1 year postoperatively. Lip pressure was measured using the Lip De Cum LDC-110R® (Cosmos Instruments Co., Ltd., Tokyo, Japan). CT images were reconstructed using ProPlan CMF (Materialize, Belgium), and zygomaticus major muscle width and CT values were analyzed. To the best of our knowledge, no previous studies have employed CT values to assess muscles in the oral and maxillofacial area. Results: In both class II and class III females, postoperative zygomaticus major muscle width was significantly higher than preoperative values. In class II females, postoperative zygomaticus major muscle CT values were also significantly higher than preoperative values. Simple linear regression analysis with age as the dependent variable revealed significant associations between pre- and postoperative zygomaticus major muscle widths in both groups. Additionally, simple linear regression analysis with CT values as the dependent variable demonstrated significant associations with postoperative lip-closing force in both class II and class III females. Conclusions: This study suggests that orthognathic surgery significantly modifies the zygomaticus major muscle morphology and function, impacting CT values.

Changes in computed tomography values and morphology of the condyle and glenoid fossa before and after orthognathic surgery in female jaw deformity patients

2024-12-31T15:00:00Z

Title: Changes in computed tomography values and morphology of the condyle and glenoid fossa before and after orthognathic surgery in female jaw deformity patients Author(s): Koichiro Ueki; Karen Gomi; Kunio Yoshizawa; Akinori Moroi; Young-Min Shin Abstract: This study aimed to investigate the computed tomography (CT) values and morphology of the temporomandibular joint (TMJ), specifically the condyle and glenoid fossa, in female patients with jaw deformities before and after orthognathic surgery. The maximum CT values were measured on the condylar and glenoid fossa surfaces. In addition, the height, length, and area of the glenoid fossa in the sagittal plane were evaluated for the bilateral TMJs, preoperatively and one year postoperatively. The ramus height, condylar square, ramus angle, and gonial angle were also measured. A total of 148 TMJs from 74 patients were analyzed. Both condylar and ramus heights decreased one year after surgery in class II and class III patients (P < 0.05). The glenoid fossa area significantly increased one year after surgery in class II (P = 0.0005). Significant postoperative increases in CT values were observed at the 0°, 135°, and 180° points on the condylar surface and at the 135° and 180° points on the glenoid fossa surface in class II patients (P < 0.05). These findings suggest that in class II patients, substantial morphological and CT value changes occurred in the condyle and glenoid fossa one year following orthognathic surgery.