Lateral Window Design for Maxillary Sinus Graft Based on the Implant Position.

The purpose of this study was to devise a classification and lateral window design method based on implants and to evaluate whether these classifications and methods are applicable to clinical practice. When applying the maxillary sinus elevation technique using the lateral window, possible situations were classified into four: (A) two or more sites for implants are required for maxillary sinus augmentation, (B) a single implant is required when there are no adjacent teeth, (C) a single implant is required when one adjacent tooth is present at the mesial or distal area, and (D) a single implant is required when both mesial and distal adjacent teeth are present. In order to verify whether this classification can be used in all situations, 76 patients who underwent maxillary sinus elevation with a lateral window were selected and investigated. Of them, 47 (62%) were included in Group A, 9 (12%) in Group B, 8 (11%) in Group C, and 12 (15%) in Group D. Lateral window designing in the lateral approach of sinus augmentation can be classified into four clinical situations. There were no unclassified cases. This classification and window positioning method can be applied to most cases.

A Simple and Safe Approach for Maxillary Sinus Augmentation with the Advanced Surgical Guide.

OBJECTIVE: The development of digital dentistry has contributed to the astonishing advancement of implant dentistry. Furthermore, digital technology is expected to be applied extensively to sinus augmentation, which is an advanced technique for implant surgery. This study introduces a simple method for a safer and more precise lateral window opening for sinus augmentation using a navigation program. METHODS: Five eligible patients with residual alveolar bone of 4 mm or less are presented, requiring lateral approach for sinus augmentation. Navigation system was opted for the sinus lift with simultaneous implant placement. Virtual planning started with establishing the adequate position of the lateral window based on the radiographic images and the scanned file of the dentition. The position of the window was indicated on the guide within the program. Afterwards, the virtually designed surgical guide was fabricated either with 3D printer or milling machine for the actual surgery. RESULTS: All the patients who underwent surgery with the surgical guide showed no sign of clinical complications including pain, swelling, nausea, epistaxis, or early loss of the implants. Results of radiographic evaluation also showed adequate placement of the implants in a pre-planned position, and the sinus window was also formed in the desired location. CONCLUSION: Lateral window opening combined with digital navigation system is believed to be a promising technique for a more precise as well as safer sinus augmentation.

Long-term Stability after Reduction of Mandible Fracture by Keyhole Plate: Evaluation at the Time of Plate Removal.

BACKGROUND: Various types of miniplates have been developed and used for the reduction of facial bone fractures. We introduced Yang's Keyhole (YK) plate, and reported on its short-term stability. The purpose of this study was to evaluate the long-term stability of the YK plate, as a follow-up study, by examining the patients who had used the YK plate among the patients with the reduction of mandible fractures and who visited for plate removal. METHODS: We reviewed the medical records of 16 patients who underwent mandibular fracture fixation using a YK plate (group I) and 17 patients who underwent mandibular fracture fixation using a conventional plate (group II). Assessment was then made on malunion, occlusal stability, discomfort during the application, and clinical symptoms. RESULTS: From January 2015 to December 2017, a total of 36 patients underwent mandibular fracture surgery using a YK plate. A total of 16 patients received plate removal. Among them, 15 were male and 1 female. The average age was 26 years. The applied surgical sites were the 12 on mandibular angle, 4 on mandibular symphysis, and 2 on subcondyle. The application period of YK plate was an average of 335 days. During the same period, 45 people underwent surgery on the conventional plate. A total of 17 patients received plate removal. Among them, 15 were male and 2 females. The average age was 36 years. The applied surgical sites were the 8 on mandibular angle, 4 on mandibular symphysis, and 2 on subcondyle. The application period of the conventional plate was an average of 349 days. No malocclusion occurred at the time of removal, and occlusion was stable. No patient complained of joint disease or discomfort. CONCLUSION: The YK plate system, in which the screw was first inserted and the plate was applied, for clinical convenience did not cause any particular problem and no significant difference from the conventional plate.

The accuracy and stability of the maxillary position after orthognathic surgery using a novel computer-aided surgical simulation system.

BACKGROUND: Many reports have been published on orthognathic surgery (OGS) using computer-aided surgical simulation (CASS). The purpose of this study was to evaluate the accuracy of the maxillary repositioning and the stability of the maxilla in patients who underwent OGS using a newly developed CASS program, a customized osteotomy guide, and a customized miniplate. METHODS: Thirteen patients who underwent OGS from 2015 to 2017 were included. All patients underwent a bimaxillary operation. First, a skull-dentition hybrid 3D image was rendered by merging the cone beam computed tomography (CBCT) images with the dentition scan file. After virtual surgery (VS) using the FaceGide® program, patient-customized osteotomy guides and miniplates were then fabricated and used in the actual operation. To compare the VS with the actual surgery and postoperative skeletal changes, each reference point marked on the image was compared before the operation (T0) and three days (T1), four months (T2), and a year (T3) after the operation, and with the VS (Tv). The differences between ΔTv (Tv-T0) and ΔT1 (T1-T0) were statistically compared using tooth-based reference points. The superimposed images of Tv and T1 were also investigated at eight bone-based reference points. The differences between the reference points of the bone surface were examined to evaluate the stability of the miniplate on the maxilla over time. RESULTS: None of the patients experienced complications. There were no significant differences between the reference points based on the cusp tip between ΔTv and ΔT1 (p > 0.01). Additionally, there were no significant differences between the Tv and T1 values of the bone surface (p > 0.01). The mean difference in the bone surface between Tv and T1 was 1.01 ± 0.3 mm. Regarding the stability of the miniplate, there were no significant differences between the groups. The difference in the bone surface between T1 and T3 was - 0.37 ± 0.29 mm. CONCLUSIONS: VS was performed using the FaceGide® program, and customized materials produced based on the VS were applied in actual OGS. The maxilla was repositioned in almost the same manner as in the VSP plan, and the maxillary position remained stable for a year.

Computer-Aided Surgical Simulation for Yaw Control of the Mandibular Condyle and Its Actual Application to Orthognathic Surgery: A One-Year Follow-Up Study.

Background: Favourable occlusal interdigitation and an optimized position of the mandibular condyle after surgery are essential for obtaining favourable results. The position of the condyle is determined during the operation. However, it is difficult to maintain the condyle's original position post-surgery despite the efforts of the surgeons. Indeed, a degree of rotation of the condyle is unavoidable, since it is difficult to verify whether the condyle is positioned correctly during surgery. Purpose: To maximize contact between the bone segments, the condyle was rotated around the vertical axis using surgical simulations. We examined changes to the condyle-fossa relationship after comparing virtual surgery to actual surgery. Methods: From 2015 to 2017, 20 patients were diagnosed with skeletal malocclusion and participated in computer-aided surgical simulation before undergoing orthognathic surgery. In the simulation, the mandibular condyles were rotated around the vertical axis, and the proximal segments were fixed to the distal segments using a customized miniplate and positioning device during actual surgery. This study investigated the relationship between the condyle and fossa using cone-beam computed tomography for several different time periods (preoperative (T0), virtual surgery (Tv), postoperative three days (T1) and one year (T2)). Results: The coronal and sagittal view exhibited significant differences in the mean values between T1and T0, Tv, and T2 for all joint spaces. As a result of the distance, the mean value of T2 in both the superior joint space (JS) and the lateral JS was significantly higher than that of Tv. In contrast, the mean value of Tv in the medial JS was significantly higher than that of T2. Moreover, the mean value of T2 on the axial plane was significantly larger than the values of Tv and T1. The mean value of T0 was also significantly larger than those of Tv and T1, and the mean value of Tv was larger than that of T1. Although the condyle was rotated, it exhibited a tendency to return to its preoperative position. There was no statistically significant difference in functional evaluation between T0 and T2. Conclusion: Our method of using yaw control for the condyle during virtual surgery and transferring this technique to the actual surgery can improve the conventional surgical technique by positioning the proximal segment in a pre-planned position, thus achieving optimal results.

Clinical reliability of zirconium abutment in implant restorations in the English and Korean literature.

BACKGROUND: This study aimed to evaluate the mechanical, biological, and esthetic stability of a zirconium abutment according to evidence-based dentistry. MAIN TEXT: An electronic search was performed. Domestic studies were found using the keywords "zirconia abutments" and "zirconium abutment" in KMbase, KoreaMed, and the National Assembly Library, and international studies were found using the same keywords in PubMed. All identified studies were divided by evidence level from the viewpoint of the research type utilizing the evidence-based review manual. A total of 102 domestic studies (with Korean language) were found, and 9 of these studies were selected. In these nine studies, 3 had evidence level 3 and 6 had evidence level 4. A total of 97 international studies (with English language) were found, and 19 were selected. Among these 19 studies, 5 had evidence level 2 and 7 had evidence level 3, whereas the remainder had evidence level 4. According to the studies, zirconium abutments are mechanically, biologically, and esthetically stable, but the evidence level of these studies is low, and the follow-up duration is no longer than 5 years. CONCLUSIONS: All examined studies verified the mechanical stability of zirconium abutments for a period no longer than 5 years. Therefore, a long-term clinical observation is needed. Zirconium abutments are thought to be biologically stable, but they are not superior to titanium abutments. As the esthetic stability of such abutments had a low evidence level in the studies that examined here, a much higher evidence level is needed.