Assessment of the relationship between impacted mandibular third molars and inferior alveolar nerve with dental 3-dimensional computed tomography.
ABSTRACT The purpose of this study was to assess the capacity of dental 3-dimensional computed tomography (3D-CT; limited cone-beam CT) to predict the exposure and injury of the inferior alveolar nerve (IAN) after mandibular third molar extractions.
This study was a retrospective case series of patients who presented for extraction of mandibular third molars. Subjects eligible for study enrollment were those who underwent preoperative dental 3D-CT because the mandibular third molars were determined to be extremely close to the IAN on panoramic radiogram. The predictive variable was the anatomic relation of the IAN and third molar apices and was a binary variable, contact or noncontact. The primary outcome variable was IAN exposure, and the secondary outcome variable was IAN injury.
From January 2006 to August 2007, 1,853 mandibular third molars in 1,539 patients were extracted. Among them, dental 3D-CT was performed on 53 third molars in 47 patients. The mandibular third molars were judged to make contact with the mandibular canal on dental 3D-CT images in 35 cases (66%). Intraoperative IAN exposure was observed in 17 (49%) contact cases and 2 (11%) noncontact cases on dental 3D-CT images. Of 53 cases extracted after dental 3D-CT examinations, IAN injury occurred in 8 cases (15%). IAN exposure led to IAN injury in 36.8% of cases, whereas IAN injury occurred in only 2.9% of cases without IAN exposure. Although the incidence of IAN injury in the molar-canal contact cases was 23%, all 8 cases with IAN injury (100%) were included in these contact cases.
When viewing the anatomic relation between the IAN and mandibular third molar root apices using dental 3D-CT, contact of the 2 anatomic structures results in an increased risk for IAN exposure or injury.
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ABSTRACT: The purpose of the present study was to determine whether panoramic radiographs could predict physical contact between the mandibular third molar and the mandibular canal on limited cone-beam computed tomography, known as dental 3D-CT (3-dimensional computed tomography [3D-CT]). The association of images between the panoramic radiograph and the dental 3D-CT was investigated in a cross-sectional study. Seventy-three lower third molars in 65 patients were examined. Findings of absence or presence of the white line of the mandibular canal wall on panoramic radiographs and contact or separation between the tooth and the mandibular canal on dental 3D-CT were compared. Absence of a superior white line on panoramic radiography was associated with an increased risk of contact between the third molar and the mandibular canal on dental 3D-CT, even when the effects of tooth position, age, and gender were taken into account. The multivariate adjusted odds ratio was 10.79. Women were more likely to have contact between the 2 structures on dental 3D-CT when their panoramic radiograph showed absence of the white line. Panoramic radiography is useful for predicting to a limited extent physical contact between the mandibular third molar and the mandibular canal on dental 3D-CT.Journal of Oral and Maxillofacial Surgery 08/2007; 65(7):1303-8. · 1.33 Impact Factor
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ABSTRACT: In this prospective study, we sought to determine the incidence of inferior alveolar nerve (IAN) paresthesia in patients with an exposed IAN bundle seen intraoperatively. We included consecutive patients undergoing third molar surgery in whom an exposed IAN bundle was seen in the third molar socket intraoperatively. Data recorded from patients included radiographic findings, variations in surgical method, intraoperative findings, complications, and postoperative sequelae. Patients were reviewed 1 week after surgery and evaluated subjectively and objectively to determine the incidence of paresthesia when the IAN bundle was exposed. Patients with paresthesia were followed for 2 years or until it resolved. An exposed IAN bundle was seen in 192 operation sites in 170 patients over a 5-year period, of which 166 patients with 187 operation sites were included in this study. Thirty-eight operation sites (20.3%) showed paresthesia at 1 week after surgery (95% confidence interval, 14.5% to 26.1%); 20 sites (15.0%) showed abnormal objective assessment results. By 3 months from surgery, 57.9% of nerves had recovered to normal sensation, 65.8% of nerves recovered by 6 months, and 71.1% of nerves recovered by 1 year. Eight patients were lost to follow-up. Logistic regression showed that the operator, male gender, older age, and root curvature were significant risk factors for paresthesia. Sighting an exposed intact IAN bundle during third molar surgery indicates its intimate relationship with the third molar and carries a 20% risk of paresthesia, with a 70% chance of recovery by 1 year from surgery.Journal of Oral and Maxillofacial Surgery 06/2004; 62(5):592-600. · 1.33 Impact Factor
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ABSTRACT: 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. 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. 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. 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.Journal of Oral and Maxillofacial Surgery 05/2003; 61(4):417-21. · 1.33 Impact Factor