Preoperative Panoramic Radiographs Research Articles

Panoramic radiographic risk factors for inferior alveolar nerve injury after third molar extraction

Purpose: The purpose of this study was to estimate the association between specific panoramic radiographic signs and inferior alveolar nerve (IAN) injury during mandibular third molar removal. Patients and Methods: A case-control study design was used; the sample consisted of patients who underwent removal of impacted mandibular third molars. Cases were defined as patients with confirmed IAN injury after third molar extraction, whereas controls were defined as patients without nerve injury. Five surgeons, who were blinded to injury status, independently assessed the preoperative panoramic radiographs for the presence of high-risk radiographic signs. Bivariate analyses were completed to assess the relationship between radiographic findings and IAN injury. The sensitivity, specificity, and positive and negative predictive values were computed for each radiographic sign. Results: The sample was composed of 8 cases and 17 controls. Positive radiographic signs were statistically associated with an IAN injury (P <.0001). The presence of radiographic sign(s) had positive predictive values that ranged from 1.4% to 2.7%, representing a 40% or greater increase over the baseline likelihood of injury (1%) for the individual patient. Absence of these radiographic findings had a strong negative (>99%) predictive value. Conclusions: This study confirms previous analyses showing that panoramic findings of diversion of the inferior alveolar canal, darkening of the third molar root, and interruption of the cortical white line are statistically associated with IAN injury. Based on the estimated predictive values, the absence of positive radiographic findings was associated with a minimal risk of nerve injury, whereas, the presence of one or more of these findings was associated with an increased risk for nerve injury. © 2003 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 61:417-421, 2003

下顎枝垂直骨切り術における簡便な骨切り線決定法とその再現性

In intraoral vertical ramus osteotomy (IVRO), the important issue is how to decide the initial point of the osteotomy to avoid injuring the mandibular nerves. We had developed a simple technique to transfer the initial point of the osteotomy determined by the preoperative panoramic radiograph to the actual ramus. This technique was recently modified. The aim of the present study was to introduce this modified technique and to confirm its better reproducibility.IVRO using our technique was performed in seven mandibular prognathism cases. A highly experienced surgeon in this technique performed the surgery on the right side, while seven oral surgeons who had had no experience of IVRO performed it on the left side. Positional accuracy of the initial point of osteotomy was compared between the experienced surgeon and the unexperienced surgeons.The maximum discrepancies between the scheduled and performed osteotomy points were 1.1mm anteriorly, 1.3mm posteriorly for the highly experienced surgeon, and 1.1mm anteriorly, 1.7mm posteriorly for the unexperienced group. The median and interquartile range of the absolute discrepancies were 1.1mm and 0.3mm for the experienced surgeon, and 0.8mm and 0.6mm for the unexperienced group, respectively. No significant differences were found between the two groups. In this series, transient hypesthesia of one side of the lower lip was documented in a case who underwent IVRO with genioplasty. It was not clear whether the hypesthesia was related to IVRO or geni oplasty.This study shows the efficacy and safety of this modified technique even when performed by less experienced surgeons.

Condylar resorption after bicortical screw fixation of mandibular advancement.

This study evaluated long-term condylar resorption after mandibular advancements stabilized with bicortical screws. One hundred mandibular deficiency patients who underwent bilateral sagittal split osteotomies (BSSO) fixed with three bicortical screws per side, and who were followed for a minimum of 1 year with complete radiographic records, were evaluated. Preoperative panoramic radiographs were traced and superimposed as a best fit over long-term panoramic radiographs. Cephalometric tracings were available on all patients preoperatively, immediately after surgery, 6 to 8 weeks after surgery, and at long term after surgery. These tracings were used to show the amount of the initial advancement and any changes that occurred between 6 to 8 weeks and long term in those patients who exhibited 10% or greater changes in their condylar height. Preoperative temporomandibular joint signs and symptoms were recorded on all patients before surgery and at 6 months after surgery. There were 10 patients who had 10% or greater vertical change in their condyles; all changes were unilateral. Large advancement (P > .009) and preoperative temporomandibular joint symptoms (P > .01) statistically correlated with long-term postoperative condylar resorption. There was not a direct correlation between the amount of vertical change in the condyle and the amount of relapse. There was an improvement in temporomandibular joint symptoms for the group as a whole and in the group with condylar resorption. Patients with large advancements and preoperative temporomandibular joint symptoms appear to be at risk for condylar resorption. These results are similar to those from other studies in which rigid fixation or miniplates were used for cases of mandibular advancement.

Paresthesia of the Inferior Alveolar Nerve following the Extraction of the Mandibular Third Molars: A Literature Review of its Causes, Treatment, and Prognosis

Mandibular paresthesia is an unfortunate complication after the extraction of mandibular third molars. Damage to the inferior alveolar nerve may occur via direct or indirect injury. Careful evaluation of pre-operative panoramic radiographs with regard to root configuration and intimacy to the mandibular canal are most important. Various surgical techniques may be dictated by the radiographic presentation. When paresthesia does occur, a simple yet thorough mechanism for documentation is required. This article reviews paresthesia of the inferior alveolar nerve as a result of the extraction of the mandibular third molars.

Fabrication of a maxillary prosthesis using dental implants and an “overdenture” attachment. A clinical report

A .%-year-old woman with controlled hypothyroidism and mild arthritis began treatment in 1971. The patient’s maxillary teeth and several mandibular teeth were lost as a result of periodontitis. A blade implant was placed in the mandibular right quadrant at that time. The region is still healthy and providing excellent support. The patient’s major concern was an inability to function properly with her conventional maxillary complete denture because of a chronic gagging reflex. She retained the denture with adhesive for many years. Intramucosal inserts were placed to eliminate the use of denture adhesives and minimize the patient’s severe gag reflex by improving maxillary denture stabilizati0n.l The inserts allowed fo:r removal of some of the acrylic resin on the palate, which reduced the gag reflex. The denture was well retained for 3 years, after which the underlying mucosal tissues became hypertrophied, inflamed, and irritated, resulting in the removal of the intramucosal inserts. The tissues were conditioned by use of a series of soft lining materials after minimal surgical revision. With the advent of the intramobile cylinder implants (IMZ), (Interpore International, Irvine, Calif.), osteointegrated dental implant system, a new maxillary prosthesis using dental implants was planned. Preoperative panoramic and intraoral radiographs indicated sufficient vertical bone height and proper bone pattern to accept endosseous implants (Fig. 1). To achieve stablility of the maxillary prosthesis over the IMZ dental implants, many different concepts were considered, including magnets, O-ring attachments, Ceka attachments, and the Stern ERA (APM Sterngold, Atteboro, Mass.) attachment. The ERA “overdenture” attachment was selected because of its resilient properties.

Dysesthesia after Mandibular Third Molar Surgery: A Retrospective Study and Analysis of 1,377 Surgical Procedures

To statistically associate specific factors of surgical extraction of third molars with mandibular nerve dysesthesia, records of patients were reviewed for preoperative panoramic radiographs, complete operative and anesthetic records, preoperative and postoperative notes, and histories. Data were then tabulated and the cases of altered sensation were compared with cases of unaltered sensation.