External Oblique Ridge Research Articles

Is Panoramic Imaging Equivalent to Cone-Beam Computed Tomography for Classifying Impacted Lower Third Molars?

Preoperative recognition of the relative position of the mandibular third molars may contribute to more reliable treatment planning, avoiding injuries and decreasing surgical and recovery times. The research questions for this study were as follows: 1) Is panoramic radiography (PR) equivalent to cone-beam computed tomography (CBCT) in determining the degree of mandibular third molar impaction? 2) For PR, is the external oblique ridge a more reliable reference to determine the degree of mandibular third molar impaction? This retrospective case-series study assessed whether the imaging modalities (primary predictor variable) are equivalent in determining the degree of impaction of third molars (primary outcome variable) according to the parameters of the Pell and Gregory classification. Two oral and maxillofacial radiologists evaluated PR and CBCT images presenting at least 1 mandibular third molar. The degrees of impaction related to the ascending ramus and related to the external oblique ridge (secondary outcome variables) also were assessed. The agreement rates between PR and CBCT were presented, and the imaging modalities were compared by the McNemar-Bowker test (α=.05). A total of 173 patients were included (66 male and 107 female patients). Among these patients, 313 mandibular third molars were assessed. In relation to the occlusal plane, the agreement rate between PR and CBCT was 82.1% for Pell and Gregory class A, 90.5% for class B, and 65.6% for class C (P=.116). The overall agreement rate between the classifications in relation to the mandibular ramus on PR and CBCT ranged from 66.8% (considering the ascending ramus, P<.001) to 76.4% (considering the external oblique ridge, P<.001). PR performs similarly to CBCT in the classification of impaction in relation to the occlusal plane. However, PR shows a tendency to underestimate the space for accommodation of the third molar compared with CBCT. Furthermore, the external oblique ridge is not a reliable alternative landmark on PR.

Comparison of findings of radiographic and fractal dimension analyses on panoramic radiographs of patients with early-stage and advanced-stage medication-related osteonecrosis of the jaw

The aim of this study was to compare the panoramic radiographs of patients with early-stage and advanced-stage medication-related osteonecrosis of the jaw (MRONJ) for differences in radiographic findings and fractal dimension (FD). Data were collected from the medical records of 66 patients confirmed as having MRONJ. Panoramic radiographs of 66 patients (group I; without bone exposure; and group II; with bone exposure) were evaluated for the following signs; osteolysis, cortical erosion, focal and diffuse sclerosis, sequestrum, lamina dura thickening, enhancement of the inferior alveolar canal (IAC), persistent alveolar socket, pathologic fractures, and enhancement of the external oblique ridge. FD values were also compared between groups. The signs of focal and diffuse sclerosis, sequestrum, and enhancement of the IAC were observed significantly more often in group II than group I (P < .05). The mean FD values were 1.42 ± 0.11 in group I and 1.44 ± 0.18 in group II and were significantly different only in 1 region but not significantly different overall. Radiographic alterations of bone structures appeared more frequently in patients with advanced stages of MRONJ. No significant difference was detected in the FD values among the tested regions except the cancellous bone above the mandibular canal on the distal side of the mental foramen.

Computer-Aided Design/Computer-Aided Manufacturing Cutting Guides for Odontectomy of Deeply Impacted Mandibular Third Molars.

AIM:To evaluate a new technique for surgical removal of deeply impacted mandibular third molars (DIMTM), using computer-guided cutting guide to maintain inferior alveolar nerve (IAN) integrity and the covering buccal bone.PATIENTS AND METHODS:Eighteen cases indicated for removal of DIMTM. Cone-beam Computed Tomography (CBCTs) used to determine the tooth’s relation to the IAN. Computer-guided software used for fabrication of surgical cutting guide stent to expose the impacted tooth and repositioning of bone after odontectomy without fixation. Clinical assessment included a neurosensory deficit of IAN, pain using a visual analogue scale (VAS), facial swelling, and maximal mouth opening (MMO). CBCTs were taken immediately and six months postoperatively to evaluate position and healing of bone.RESULTS:None of the patients showed a permanent neurological deficit of IAN while all patients showed normal parameters of pain, facial swelling and MMO.CONCLUSION:this technique has shown the accurate determination of the bony window cuts with subsequent preservation of IAN and external oblique ridge.

Surgical Treatment of Osteoma in the Basilar Region of the Mandible.

Osteoma is an uncommon benign osteogenic tumor characterized by the proliferation of compact and cancellous bone. The objective of this study was to report a case of osteoma in the basilar region of the mandible. The patient reported no pain, but the affected area was tender to touch and there was esthetic concern because of the apparent swelling. The mass measured approximately 5 cm in diameter and extended to the lingual area of the mandible. A vestibular approach was used for surgical treatment. After infiltration of a local anesthetic and vasoconstrictor, to expose the mandibular ramus, an incision was made with an electric scalpel along the external oblique ridge through the mucosa, submucosa and muscle, fascia and periosteum until the lower second molar, 3 to 5 mm inferior to the mucogingival junction. A mucoperiosteal flap was raised until the base of the mandible to access the tumor. Osteotomy was performed and the tumor was removed. The patient shows no recurrence of the tumor after 1 year and 6 months of follow-up. Periodical clinical and radiographic follow-up are satisfactory since recurrence is rare.

The variable position of the inferior alveolar nerve (IAN) in the mandibular ramus: a computed tomography (CT) study.

This study was designed to quantify the important anatomical landmarks and the path of the inferior alveolar nerve (IAN) within the human mandibular body and ramus, in particular with reference to the bilateral sagittal split osteotomy (BSSO). Four hundred and eleven CT scans were studied, 299 of these were involved in determining the position of lingula; and 230 were involved in determining the course of IAN in the mandibular molar region, namely from the mesial of the mandibular first molar to the distal of the mandibular second molar; 118 were involved with both measurements. On average, the lingula was located 17.0 ± 2.2mm from the external oblique ridge; 11.6 ± 2.0mm from the internal oblique ridge; 17.2 ± 2.7mm from the sigmoid notch; and 15.6 ± 1.9mm from the posterior border of the mandible. The course of the IAN in the mandibular molar region was found to descend vertically from the distal of the mandibular second molar (7) to reach its lowest point between the first and second molars (6 and 7), and then ascend towards the mesial of the first molar (6). Horizontally, the IAN was found to traverse medially between the distal of the 7 and the middle of the 7, and then changes its path laterally towards the mesial of the 6. Precise knowledge of the individual's position of the IAN will help surgical planning.

A comparative study between intraoral external oblique ridge fixation with transbuccal lateral cortical plate fixation for treatment of mandibular angle fractures, a prospective study

A comparative study between intraoral external oblique ridge fixation with transbuccal lateral cortical plate fixation for treatment of mandibular angle fractures, a prospective study

Dental occlusal-surface-supported titanium guide to assist cutting and drilling in mandibular bilateral sagittal split osteotomy.

Cutting and drilling guides manufactured using computer-aided design/computer-aided manufacturing (CAD/CAM) technologies have attracted increasing interest in orthognathic surgery, particularly in complex cases. The development of these guides requires virtual surgery planning and three-dimensional modelling before they can be printed in titanium, polyamide or resin. We report the use of a personalized titanium device to assist bilateral sagittal split osteotomy (BSSO) with or without genioplasty combined with individual implants for repositioning and fixation. This one-piece guide for both sides of the BSSO allows the initiation of cutting and drilling with less invasive drill placement and greater accuracy. The titanium guide was manufactured using CAD/CAM technologies after conventional digital planning of BSSO. Intraoperatively, the guide was fitted on each side of the mandibular occlusal surface and screwed to predesigned drill holes. The guide facilitates the predrilling of screw holes and the initiation of cutting for buccal, lingual and external oblique ridge corticotomy using a piezosurgery device. Based on our experience, we think that this guide is a promising new tool to assist BSSO. It helped limit the extent of tissue detachment required and provided the strength necessary for accurate bone cutting and drilling. It also allowed the accurate fixation of preformed plates to obtain occlusion as per virtual planning.

Special Design of Removable Partial Denture Restoration Following Surgical Resection of Mouth Floor Neoplasm

This clinical report describes a special removable partial denture design and fabrication in the mandibular teeth rehabilitation of a patient diagnosed with carcinoma in the mouth floor Following surgical resection of partial teeth and mandible a severe scar adhesion between tongue and mouth floor tissue occurred which was difficult to reconstruct the mandible and teeth defect with removable partial denture A specific restoration design with clasps on abutment teeth lingual side and denture base on external oblique ridge which can effectively escape from the adhesive area was indicated and discussed

An Assessment of Factors Influencing the Difficulty in Third Molar Surgery.

Background and Objectives:Surgical removal of a mandibular impacted third molar is one among the most common oral surgical procedures. The objective of this study was to assess and identify risk indicators influencing extended operation time in relation to the surgical removal of mesioangular impacted mandibular third molar, position A, Class I and to evaluate the incidence of postoperative swelling, trismus, and pain.Materials and Methods:A prospective cohort was implemented and the patients who presented for mandibular third molar removal which were impacted in position A, Class I were enlisted for the study. During 1 year between July 2014 and June 2015, a total of 40 patients were enrolled in the study. The evaluation of patient variables and radiographic variables was done preoperatively. Depending on the duration of time taken for an operation, patients were divided into three groups: Group I, Group II, and Group III. Postoperative complications such as swelling, trismus, and pain were assessed in each of the patients.Statistical Analysis:The statistical analysis was done among the groups using Chi-square test, and ANOVA.Results:Among the six variables studied in this study including patient variables and radiographic variables, maximum interincisal opening, external oblique ridge, and root morphology were found to be dependent factors which influence the operating time. Moreover, other variables such as the crown root width ratio and the number of roots were independent factors. Swelling, trismus, and pain were statistically significant among groups and were directly related to operating time.Conclusion:We consider that the outcome of surgical removal of mandibular impacted third molar, position A, Class I depends significantly on relevant patients characteristics and radiographic variables which should be evaluated preoperatively as they are predetermined factors to avoid postoperative morbidity.

Management of Mandibular Angle Fractures by Two Conventional 2.0-mm Miniplates: A Retrospective Study of 389 Patients.

Fractures of the mandibular angle account for 23 to 42% of all facial fractures with a high complication rate (0-32%). Although the ideal treatment remains debatable, two main procedures are commonly used to manage the majority of mandibular angle fractures that are open reduction and internal fixation by a noncompression miniplate placed on the external oblique ridge with or without a second miniplate on the outer cortex. The purpose of this study was to describe our management of mandibular angle fractures by two noncompression miniplates placed on the outer cortex via a transbuccal approach. Medical records and radiographic examination of 389 patients (258 males [66.3%] and 131 females [33.7%]) operated from January 2000 to December 2012 were retrospectively reviewed. Postoperative complications including malocclusion, infection, wound dehiscence, nonunion, and reoperative surgery were recorded and analyzed. Fifty-three patients developed postoperative complications (overall complication rate: 13.6%). No significant difference was found in the complication rate by age and gender variables and regarding the interval between the trauma and the operation and the presence of the teeth in the line of fracture. A higher rate of complications was found among patients with alcohol/drug addiction and in patients with multiple-site involvement. The findings of this study suggest that the use of two transbuccal miniplates placed on the outer cortex for the internal fixation of mandibular angle fracture provided a low rate of complications. The global incidence of screw loosening, wound dehiscence, plate exposure, infection, reoperation, and plate removal were similar with the data reported in the literature with improved health outcomes, lower postoperative morbidity, and a faster return to normal life.

Evaluation of Mandibular Anatomy Associated With Bad Splits in Sagittal Split Ramus Osteotomy of Mandible.

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.

Purpose: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.Methods: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.Results: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).Conclusion: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.

EVALUATION OF DYNAMIC COMPRESSION MINIPLATES IN TREATMENT OF MANDIBULAR ANGLE FRACTURES USING TROCAR

Abstract: Introduction: Mandibular angle fractures (MAFs) account for 23% to 42% of all mandibular fractures. The frequent involvement of the angle in mandibular fractures can be attributed to its thin cross-sectional bone area and the presence of a third molar Objectives: The aim of this study was to evaluate clinically and radiologically the use of two dynamic compression miniplates in treatment of mandibular angle fractures using Trocar instrumentationMaterials and methods: The study was conducted on ten patients diagnosed with a single mandibular angle fracture indicated for open reduction and internal fixation. The fracture was exposed through transoral vestibular incision and reduced under general anesthesia. Third molar tooth in the fracture line was extracted. Temporary Maxillomandibular fixation was done using 26gauge stainless steel wires with arch bars. One dynamic compression miniplate was fixed on the external oblique ridge. The second miniplate was fixed on the lower border of the mandible using Trocar instrumentation. Results: Pain, edema and trismus decreased significantly over the follow up period. Maximum interincisal mouth opening and bone density along the fracture line increased significantly over the follow up period. Five patients had parasthesia of the inferior alveolar and mental nerve preoperatively. The parasthesia decreased progressively from the fourth week. Postoperative panorama radiographs showed adequate reduction and increase in bone density along the fracture line. No postoperative complication occurred. Conclusion: Two 2.0 mm dynamic compression miniplates are suitable for treatment of mandibular angle fractures using Trocar instrumentation. Key words: Dynamic compression miniplates, mandibular angle fractures, Trocar.

Routine removal of the plate after surgical treatment for mandibular angle fracture with a third molar in relation to the fracture line.

Purpose: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.Subjects and Methods: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.Results: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.Conclusions: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.

Harvesting Mandibular Ramus Bone Grafts Using Ultrasonic Surgical Device: Report of 20 Cases

Successful osseointegration of the dental implants requires sufficient bone volume surrounding implant site. The mandibular ramus is considered reliable donor site for reconstructing alveolar ridge defects prior to dental implant placement. The aim of this study was to present the clinical efficiency of using ultrasound surgery for harvesting mandibular ramus bone graft. 20 patients (10 male, 10 female; mean age 47.5 ± 11.4years) with insufficient bone volume, who underwent autogenous bone grafting prior to implant placement, were presented. The grafts were harvested from the ascending ramus along with the external oblique ridge using an ultrasound surgical device (Piezosurgery, Mectron, Italy) from 20 donor sites and used to augment alveolar ridge atrophies. After waiting 4 to 5 months for healing grafted sites, 48 dental implants were inserted. Clinical parameters such as inferior alveolar nerve (IAN) damage, complications at donor and recipient site, the size of the graft and implant placement at the proper site were evaluated retrospectively. Mean graft length was 20.1mm (SD=2.73), and mean graft width was 12mm (SD=2.47). Of 20 recipient sites, 20 healed uneventfully, and of 20 donor sites 18 healed uneventfully. Only one patient had transient altered sensitivity of the lower lip. Ultrasound surgery allowed precise and smooth bone cutting with better intraoperative visibility. Specially angulated tip of the devise made inferior horizontal cut easier and safer. The results of this study suggest that the use of ultrasound surgery is an effective method for harvesting bone grafts from mandibular ramus with avoidance of any major complication.

Impacted third molars in sagittal split osteotomies in mandibular prognathism and micrognathia.

Background:The timing of removal of mandibular third molars (M3) in Sagittal Split Osteotomy (SSO) has been an issue of contention. The aim of this retrospective study is to identify the incidence of unfavorable fractures during SSO with the presence of M3 and to identify the association between unfavorable fractures with the factors specifically related to the M3.Materials and Methods:Retrospective analysis of consecutive bilateral sagittal split osteotomy (BSSO) patient's treatment records of 208 patients treated by a single surgeon was analyzed. The position of M3, fracture details, and demographics were collected. Descriptive statistics and Chi-square tests were employed in SPSS package. A P ≤ 0.05 was taken as significant.Results:There were altogether 416 SSO performed. M3 was completely impacted in 88.9% of all instances, and in 85.6% of the instances, the bulk of the M3 was identified to be above the external oblique ridge. In 59.4% of the cases, M3 was positioned in alignment with the arch as observed during surgery. There were about 27 (6.5%) instances of unfavorable splits. A statistically significant relationship was observed with M3 root morphology and axial position of M3.Discussion:This study for the first time has confirmed the spatial positioning of M3 as one of the several causes of unfavorable splits during SSO. An impacted M3 that lies below the oblique ridge, distoangularly/vertically oriented, with divergent/supernumerary root would cause unfavorable splits when the spreader is not used properly. Potential causes and influencing factors of the unfavorable splits are discussed.

Reverse sliding onlay graft from the chin for lateral reconstruction of the alveolar ridge

Surgical techniques for reconstruction of the transverse alveolar ridge include bone splitting for cases with moderate bone loss, or onlay grafting using various kinds of local grafts or bone-replacement materials, or both. 1 Aghaloo T.L. Moy P.K. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant placement?. Int J Oral Maxillofac Implants. 2007; 22 ([Erratum in: Int J Oral Maxillofac Implants 2008; 23:56]): 49-70 PubMed Google Scholar , 2 Chiapasco M. Zaniboni M. Boisco M. Augmentation procedures for the rehabilitation of deficient edentulous ridges with oral implants. Clin Oral Implants Res. 2006; 17: 136-159 Crossref PubMed Scopus (428) Google Scholar While bone splitting requires thick bone and normal bicortical configuration together with a reliable and relatively elastic cancellous layer, the onlay graft is useful for all other cases. For an onlay graft bone is generally harvested locally from the symphysis or the external oblique ridge, reshaped, and secured with osteosynthesis screws on the deficient bone.

Transoral Miniplate Fixation of Mandibular Angle Fracture with and without 2 Weeks of Maxillomandibular Fixation: A Clinical Trial Study

Background and Objectives The ideal line of osteosynthesis in mandibular angle fractures indicates that a plate might be placed either along or just below the external oblique ridge. Some authors believe that using one miniplate at this line at the mandibular angle region provides sufficient strength to stabilize the fracture but others imply a second plate is required. Such controversies exist in the use of maxillomandibular fixation (MMF). The intention of the present study was to compare efficiency and complications of using one miniplate with and without MMF in mandibular angle fractures. Methods and Materials Forty patients with facial trauma with mandibular angle fractures including displaced and unfavorable fractures were categorized into two groups of 20 persons. In all patients, one miniplate was placed on the external oblique ridge. In the first group, patients had light maxillomandibular elastic bands just after surgery but no rigid MMF. In the second group, patients had rigid MMF for 2 weeks after surgery. Patients were followed to evaluate complications and treatment efficiency. Conclusions Our study showed that use of a single miniplate in the external oblique ridge is a functionally stable treatment for all types of angle fractures (including displaced and unfavorable fractures) except comminuted and long oblique fractures, which were not included in our study. Use of postoperative MMF did not improve the results.

Nonsurgical correction of a Class III malocclusion in an adult by miniscrew-assisted mandibular dentition distalization

This article reports the successful use of miniscrews in the mandible to treat a 20-year-old Mongolian woman with a chief complaint of anterior crossbite. The patient had a skeletal Class III malocclusion with a mildly protrusive mandible, an anterior crossbite, and a deviated midline. In light of the advantages for reconstruction of the occlusal plane and distal en-masse movement of the mandibular arch, we used a multiloop edgewise archwire in the initial stage. However, the maxillary incisors were in excessive labioversion accompanied by little retraction of the mandibular incisors; these results were obviously not satisfying after 4 months of multiloop edgewise archwire treatment. Two miniscrews were subsequently implanted vertically in the external oblique ridge areas of the bilateral mandibular ramus as skeletal anchorage for en-masse distalization of the mandibular dentition. During treatment, the mandibular anterior teeth were retracted about 4.0 mm without negative lingual inclinations. The movement of the mandibular first molar was almost bodily translation. The maxillary incisors maintained good inclinations by rotating their brackets 180° along with the outstanding performance of the beta-titanium wire. The patient received a harmonious facial balance, an attractive smile, and ideal occlusal relationships. The outcome was stable after 1 year of retention. Our results suggest that the application of miniscrews in the posterior area of the mandible is an effective approach for Class III camouflage treatment. This technique requires minimal compliance and is particularly useful for correcting Class III patients with mild mandibular protrusion and minor crowding.

Temporary anchorage device with interchangeable superstructure for mandibular tooth movement

The aim of this report is to introduce our new temporary anchorage device (TAD) for the mandible, the superstructure of which is removable and enables mesiodistal movement, intrusion and extrusion, as well as expansion and constriction, employing the palatal implant with the same system as we reported previously. The TAD has a removable superstructure on a plate fixed on two screws. It is positioned on the external oblique ridge, and the superstructure shape can be changed into various forms. Case 1 was a 19-year old woman with an anterior open bite; her mandible was shifted to the left. The molar relationship was Class III on the right and Class II on the left, and inclination of the occlusal plane was observed. Intrusion of the maxillary right molars and distalization of the left molars were performed using the palatal implant. Distalization of the mandibular right molars was achieved using the TAD. Case 2 was a 38-year old man with an anterior cross bite and deviation of the mandible to the left. Distalization of the mandibular right molars and movement of the midline to the right were achieved using the TAD. The TAD system can handle all force systems, move teeth effectively, and save treatment time.