external oblique ridge [keywords]
- Evaluation of Mandibular Anatomy Associated With Bad Splits in Sagittal Split Ramus Osteotomy of Mandible. [Journal Article]
- J Craniofac Surg 2016 Jul; 27(5):e500-4.
This study aimed to identify risk factors associated with bad splits during sagittal split ramus osteotomy by using three-dimensional computed tomography.This study included 8 bad splits and 47 normal patients without bad splits. Mandibular anatomic parameters related to osteotomy line were measured. These included anteroposterior width of the ramus at level of lingula, distance between external oblique ridge and lingula, distance between sigmoid notch and inferior border of mandible, mandibular angle, distance between inferior outer surface of mandibular canal and inferior border of mandible under distal root of second molar (MCEM), buccolingual thickness of the ramus at level of lingula, and buccolingual thickness of the area just distal to first molar (BTM1) and second molar (BTM2).The incidence of bad splits in 625 sagittal split osteotomies was 1.28%. Compared with normal group, bad split group exhibited significantly thinner BTM2 and shorter sigmoid notch and inferior border of mandible (P <0.05). However, for BTM1 and buccolingual thickness of the ramus at level of lingula, there was no statistical difference between the 2 groups. Mandibular angle, anteroposterior width of the ramus at level of lingula, external oblique ridge and lingula, and MCEM were not significantly different between the groups.This study suggests that patients with shorter ramus and low thickness of the buccolingual alveolar region distal to the second molar had a higher risk of bad splits. These anatomic data may help surgeons to choose the safest surgical techniques and best osteotomy sites.
- Lateral Ridge Augmentation with Autogenous Bone Harvested Using Trephine Drills: A Noninvasive Technique. [Journal Article]
- Open Dent J 2016.:1-11.
The aim of this pilot study was to evaluate the success rate of a chairside ridge augmentation procedure using bone autografts harvested with trephine drills and placed without the use of screws.Thirty patients were recruited for the study. After the surgical site was anesthetized and a crestal incision was made, an envelope flap was retracted using blunt dissection limited to the graft site, and the periosteum was raised intact and undamaged from the bone. The flap was extended laterally to obtain sufficient space for the bone graft. At the donor site, bone was obtained from the external oblique ridge area. A #5 or #6 trephine drill was used to harvest one or two pieces of bone. The bone blocks were placed inside the envelope flap at the recipient site, which was then sutured and covered with periodontal dressing. Antibiotics, analgesics, and mouthwash were prescribed. Measurements of ridge width were performed using CBCT before and 3 months after surgery. The pre- and post operative results were compared using paired t test.Pre- and post-operative mean ridge widths were 2.23 ± 0.79 and 5.16 ± 0.68 mm, respectively. The mean increase in width was 2.92 ± 0.89 mm(P < 0.001).This non-invasive and simple technique provided an acceptable increase in ridge width. As the sample was small, we recommend further clinical investigation with larger samples to confirm that this technique may be used successfully as an alternative to current invasive augmentation methods.
- In Vitro Mechanical Analysis of Different Techniques of Internal Fixation of Combined Mandibular Angle and Body Fractures. [Journal Article]
- J Oral Maxillofac Surg 2016 Apr; 74(4):778-85.
To evaluate in vitro resistance of 5 techniques of internal fixation of bilateral fractures involving the mandibular angle and body.Twenty-five polyurethane mandibles were used as substrates, fixed with a 2-mm fixation system, and divided into 5 groups: I, 1 4-hole plate, without intermediate space, in the neutral zone of the mandibular body and another similar plate in the external oblique ridge of the contralateral mandibular angle; II, 1 6-hole plate, with intermediate space, in the neutral zone of the mandibular body and a similar plate in the external oblique ridge of the left mandibular angle; III, 1 4-hole locking plate, with intermediate space, in the right neutral zone and another similar plate in the left external oblique ridge; IV, 2 4-hole plates, with intermediate space, one in the tension zone and the other in the compression zone of the mandibular body, and 1 4-hole plate, with intermediate space, in the external oblique ridge of the contralateral mandibular angle; V, 2 4-hole plates with intermediate space, one in the tension zone and the other in the compression zone of the mandibular body and similarly in the buccal side of the left mandibular angle. Mandibles were subjected to vertical linear load tests by a mechanical testing machine (Instron 4411, Instron Corp, Norwood, MA) to record peak load and load for displacements of 3, 5, and 7 mm.Group I had the least mechanical resistance of all groups, regardless of displacement, and group IV had the greatest mechanical resistance. Among groups II, III, and V, there was no statistically meaningful difference.Fixation of bilateral mandibular fractures involving the mandibular angle and body using 2 plates in the region of the body and 1 plate in the tension zone in the region of the mandibular angle was the technique that presented the best mechanical resistance.
- Routine removal of the plate after surgical treatment for mandibular angle fracture with a third molar in relation to the fracture line. [Journal Article]
- Ann Maxillofac Surg 2015 Jan-Jun; 5(1):77-81.
The purpose was to analyze the clinical course of surgically treated mandibular angle fractures from the viewpoint of routine removal of the plate because these fractures are associated with high rates of complications and plate removal.The subjects were 40 patients with unilateral mandibular angle fracture, which was intraorally reduced and principally fixed with a single miniplate on the external oblique ridge. The third molar in relation to the fracture line was extracted in seven patients during the surgery. Clinical course was evaluated in terms of removal of the plate, preservation of the third molar and complications.One patient showed a wound infection postoperatively, and two patients developed pericoronitis during the follow-up. These were managed with medication and local irrigation. One patient with a preserved third molar did not make a required visit and was lost from the follow-up. Removal of the plates was performed in 39 patients after confirmation of good fracture healing, mostly within a year. Twenty-four of 32 preserved third molars were simultaneously extracted. These procedures were generally performed under local anesthesia on an outpatient basis, and they did not cause any complications.Routine removal of the plate after surgical treatment for mandibular angle fractures, simultaneously with extraction of the third molar if indicated, may be beneficial to avoid complications related to the plate and the third molar later in life.
- One miniplate compared with two in the fixation of isolated fractures of the mandibular angle. [Journal Article, Review]
- Br J Oral Maxillofac Surg 2015 Oct; 53(8):690-8.
The purpose of this study was to compare one miniplate with two in the management of isolated fractures of the mandibular angle as regards wound healing, failure of hardware, scarring, weakness of the facial nerve, and overall morbidity, by making a systematic review with a meta-analysis. I made a comprehensive electronic search with no date or language restrictions in October 2014. The inclusion criteria were studies in humans, including randomised or quasirandomised controlled trials (RCT), controlled clinical trials (CCT), and retrospective studies that compared the morbidity after treatment of such fractures with one and two miniplates. Ten publications were included: three RCT, three CCT, and four retrospective studies. Three studies showed a low, and seven a moderate, risk of bias. There was a significant difference between one and two miniplates in the incidence of wound healing, failure of hardware, weakness of the facial nerve, and overall complications (p=0.04, p =0.05, p=0.002, and p=0.05, respectively). The result of the meta-analysis showed that one miniplate placed on the external oblique ridge provided a significant reduction in the incidence of wound infection and dehiscence, failure of hardware, and overall complications, compared with two miniplates, one placed on the external oblique ridge and one placed on to the ventral surface of mandible to fix the fracture.
- Mandibular bone block harvesting from the retromolar region: a 10-year prospective clinical study. [Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't]
- Int J Oral Maxillofac Implants 2015 May-Jun; 30(3):688-97.
The aim of this prospective study was to evaluate the outcome of bone block harvesting from the external oblique ridge with the MicroSaw, assess the volume of the harvested block, and identify possible morbidity and complications related to the procedure.Bone blocks were harvested from the external oblique line of the mandible according to the MicroSaw protocol. The bone blocks were split into two thinner blocks with a diamond disk according to the split bone block (SBB) technique for biologic grafting procedures.In all, 3,874 bone blocks were harvested from the external oblique line of the mandible in 3,328 patients. Four hundred nineteen patients (12.59%) underwent bilateral bone block harvesting, and 127 patients (3.82%) had more than one block harvested from the same area during the study period. In 431 cases (11.12%), only one block was required, so the second was repositioned to reconstruct its donor site. The average harvesting time was 6.5 ± 2.5 minutes, and a mean volume of 1.9 ± 0.9 cm³ was obtained (maximum 4.4 cm³). In 168 (4.33%) cases, the alveolar nerve was exposed, leading to sensory problems lasting up to 6 months. In 20 cases (0.5%), minor nerve injury resulted in hypesthesia or paresthesia that lasted for up to 1 year in most patients. No major nerve lesions with permanent anesthesia were observed. Sixty-one (1.58%) donor sites showed primary healing complications, most in smokers (80.4%). Reentry of 16 reimplanted harvested areas was performed between 6 and 40 months later, showing a well-regenerated and healed external oblique ridge.This study demonstrated that relatively large volumes of bone block graft can be retrieved in the mandible with a low complication rate. Reimplantation of half of the bone block offers the possibility for complete regeneration of the donor site.
- [Treatment of adult bimaxillary arch protrusion with micro-implant anchorage]. [English Abstract, Journal Article, Research Support, Non-U.S. Gov't]
- Shanghai Kou Qiang Yi Xue 2015 Feb; 24(1):76-82.
In this study, micro-implants were used in 15 adult patients with mild and moderate bimaxillary arch protrusion or crowding. Cephalometric analysis was used to analyze hard and soft-tissues change before and after treatment, with the aim to investigate the effects of treatment on adult bimaxillary arch protrusion with micro-implant anchorage.Fifteen adult patients with mild and moderate bimaxillary arch protrusion were selected in this study. Micro-implants were inserted into the zygomaticoalveolar ridge of maxilla and the external oblique line of mandible. A NiTi coil spring was attached to the micro-implant to drag the whole upper and lower dentition for distal movement. Cephalometrics were taken before and after treatment, and the changes of soft and hard-tissue profile were studied. SPSS13.0 software package was used to analyze the data.(1)Sixty micro-implants remained stable.(2)SNA, SNB had no significant changes (P>0.05), and the relationship between the maxilla and the mandible did not change significantly. U1/NA, U1-NA, L1/NB, L1-NB and U1/L1 changes in hard tissue had significant difference in cephalometric measurement (P<0.05). The upper and lower anterior teeth were more retrusive, and the tipping of incisor decreased significantly.(3)Cephalometric analysis showed that lateral appearance improved and soft tissue cephalometric-related measurements such as Cm-Sn-UL,LL-B'-Pos increased significantly (P<0.01). (4)Molars and incisors acquired distal movement.Micro-implant can provide not only excellent skeletal anchorage but also a novel way to distalize the whole dentition efficiently.
- A comparative finite elemental analysis of glass abutment supported and unsupported cantilever fixed partial denture. [Journal Article, Research Support, Non-U.S. Gov't]
- Dent Mater 2015 May; 31(5):514-21.
The purpose of this study was to investigate and compare the load distribution and displacement of cantilever prostheses with and without glass abutment by three dimensional finite element analysis. Micro-computed tomography was used to study the relationship between the glass abutment and the ridge.The external surface of the maxilla was scanned, and a simplified finite element model was constructed. The ZX-27 glass abutment and the maxillary first and second premolars were created and modified. The solid model of the three-unit cantilever fixed partial denture was scanned, and the fitting surface was modified with reference to the created abutments using the 3D CAD system. The finite element analysis was completed in ANSYS. The fit and total gap volume between the glass abutment and dental model were determined by Skyscan 1173 high-energy spiral micro-CT scan.The results of the finite element analysis in this study showed that the cantilever prosthesis supported by the glass abutment demonstrated significantly less stress on the terminal abutment and overall deformation of the prosthesis under vertical and oblique load. Micro-computed tomography determined a gap volume of 6.74162 mm(3).By contacting the mucosa, glass abutments transfer some amount of masticatory load to the residual alveolar ridge, thereby preventing damage to the periodontal microstructures of the terminal abutment. The passive contact of the glass abutment with the mucosa not only preserves the health of the mucosa covering the ridge but also permits easy cleaning. It is possible to increase the success rate of cantilever FPDs by supporting the cantilevered pontic with glass abutments.
- Three dimensional finite element analysis of the stress distribution around the mandibular posterior implant during non-working movement according to the amount of cantilever. [Journal Article]
- J Adv Prosthodont 2014 Oct; 6(5):361-71.
In case of large horizontal discrepancy of alveolar ridge due to severe resorption, cantilevered crown is usually an unavoidable treatment modality. The purpose of this study was to evaluate the clinical criteria for the placement of the aforementioned implant crown.The mandible model with 2 mm thick cortical bone and cancellous bone was fabricated from CT cross-section image. An external connection type implant was installed and cantilevered crowns with increasing offset of 3, 4, 5, 6, and 7 mm were connected. Vertical load and 30° oblique load of 300 N was applied and stress around bone and implant component was analyzed. A total of 14 cases were modeled and finite element analysis was performed using COSMOS Works (Solid works Inc, USA).As for the location of the vertical load, the maximum stress generated on the lingual side of the implant became larger according to the increase of offset distance. When the oblique load was applied at 30°, the maximum stress was generated on the buccal side and its magnitude gradually decreased as the distance of the offset load increased to 5 mm. After that point, the magnitude of implant component's stress increased gradually.The results of this study suggest that for the patient with atrophied alveolar ridge following the loss of molar teeth, von-Mises stress on implant components was the lowest under the 30° oblique load at the 5 mm offset point. Further studies for the various crown height and numbers of occusal points are needed to generalize the conclusion of present study.
- What method for management of unilateral mandibular angle fractures has the lowest rate of postoperative complications? A systematic review and meta-analysis. [Journal Article, Meta-Analysis, Review]
- J Oral Maxillofac Surg 2014 Nov; 72(11):2197-211.
The aim of the present study was to determine which method for internal fixation through a transoral approach has the lowest complication rate for patients with mandibular angle fractures (MAFs).To address our study purpose, we designed and implemented a systematic review with meta-analysis. To identify the studies to include in the review, a comprehensive electronic search without date or language restrictions was performed in April 2014. The inclusion criteria were studies of humans, including randomized or quasi-randomized controlled trials (RCTs), controlled clinical trials (CCTs), and retrospective studies, with the aim of comparing fixation techniques (1 vs 2 miniplates, external oblique ridge vs lateral border miniplate placement, and geometric vs conventional miniplate) in the management of MAFs. The incidence of postoperative complications was analyzed. Only those studies in which a transoral approach had been used (with or without transbuccal instrumentation) were selected.A total of 20 publications were included: 9 RCTs, 3 CCTs, and 8 retrospective studies. Eight studies had a low risk of bias, 11 studies a moderate risk of bias, and 1 a high risk of bias. A statistically significant difference was found between a single superior border miniplate and the use of 2 miniplates. The cumulative odds ratio (OR) was 0.63, indicating that the use of 1 miniplate in MAF fixation decreased the risk of postoperative complications by 37% compared with using 2 miniplates. Comparing a miniplate placed on the external oblique ridge to one placed on the lateral surface of the mandible resulted in a cumulative OR of 2.10, indicating that the use of the transbuccal miniplate decreased the risk of postoperative complications by 110% compared with a miniplate placed on the external oblique ridge. Comparing geometric and standard miniplates, the OR was 0.29, indicating that the use of a geometric miniplate decreased the risk of postoperative complications by 71% compared with using conventional miniplates.The results of the meta-analysis have shown that the use of 1 miniplate is superior to using 2 in reducing the incidence of postoperative complications in the management of MAFs. In addition, our results showed that the transbuccally placed lateral miniplate was better at reducing the incidence of postoperative complications than one placed on the external oblique ridge using a transoral approach. Finally, geometric miniplates performed better than conventional miniplates in reducing postoperative complications.