Risk factors of nerve injury during mandibular sagittal split osteotomy.

There is little objective data about whether surgical technique or mandibular anatomy are a risk for inferior alveolar nerve (IAN) injury during bilateral sagittal split osteotomy (BSSO). Orthodromic sensory nerve action potentials (SNAPs) of the IAN were continuously recorded on both sides in 20 patients with mandibular retrognathia during BSSO operation. Changes in latency, amplitude, and sensory nerve conduction velocity (SNCV) at baseline and at different stages of the operation were analyzed. The SNAP latencies prolonged, the amplitudes diminished, and the SNCVs slowed down during BSSO (P = 0.0000 for all parameters). The most obvious changes occurred during surgical procedures on the medial side of the mandibular ramus. There was a clear tendency towards more disturbed IAN conduction with longer duration of these procedures (right side R = -0.529. P = 0.02; left side R = -0.605, P = 0.006). Exposure or manipulation of the IAN usually had no effect on nerve function, but the IAN conduction tended to be more disturbed in cases with nerve laceration. Low corpus height (R = 0.802, P = 0.001) and the location of the mandibular canal near the inferior border of the mandible (R = 0.52, P = 0.02) may increase the risk of IAN injury. There was no correlation between the age of the patients and the electrophysiological grade of nerve damage.

A 5-year prospective clinical study of Astra Tech dental implants supporting fixed bridges or overdentures in the edentulous mandible.

In a 5-year prospective clinical study, 155 endosseous implants were installed in the mandible anterior to the mental foramina in 33 edentulous patients (13 males and 20 females). Usually 6 implants were installed for fixed prostheses (FP), 13 patients with 77 implants, and 4 implants for overdentures (OD) with a Dolder bar, 20 patients with 78 implants. At the time of abutment connection 1 implant in 2 patients was found to be loose and removed. However, in both these patients overdentures were successfully placed on the remaining 3 implants. Narrow-beam radiography was used for radiological evaluation. The mean (SD) total marginal bone loss in 5 years was 0.48 (0.38) mm (0.36 (0.22) mm in the FP group and 0.56 (0.45) mm in the OD group). Very few complications were reported during the 5 years, most of them being related to the superstructures. The overall cumulative implant survival rate was 98.7% (100% in the FP group and 97.4% in the OD group). The survival rate of the superstructures was 100%. The present study has demonstrated that Astra Tech implants offer reliable and predictable medium-term support for fixed prostheses and overdentures in the edentulous mandible.

Detailed tomography of periapical and periodontal lesions. Diagnostic accuracy compared with periapical radiography.

OBJECTIVE: To compare the diagnostic accuracy of detailed tomography using the Scanora system with that of conventional periapical radiography for detecting periapical and periodontal lesions. METHODS: We selected for comparison 243 periapical and 322 periodontal sites in 177 patients. Five observers independently assessed radiographs for the presence or absence of the following lesions: periapical bone changes, widening of apical and marginal ligament space, crestal erosion, vertical bone loss, furcation involvement and calculus. RESULTS: ROC analysis demonstrated no significant differences in the overall interpretation of either disease. Periapical radiography was superior (p < 0.05) to tomography for the detection of calculus. The sensitivity of tomography for periapical pathology was 87%, and 70% for periapical radiography. Sensitivities for periodontal diseases were 84% and 77%. Specificities were 81%, 90%, 77% and 79%, respectively. Differences for sensitivity and specificity were significant (p < 0.05) in relation to periapical pathology. The energy imparted during tomography was 0.92 mJ. CONCLUSION: Detailed tomography and periapical radiography performed equally well for the overall diagnosis of periapical and periodontal lesions. Tomograms differed substantially from periapical radiographs in both sensitivity and specificity for detecting periapical lesions in posterior regions. The energy imparted during detailed tomography is similar to that from two D-speed films.

Radiographic detectability of periodontal diseases. A comparison of perapical radiography with detailed zonography.

OBJECTIVE: To compare the diagnostic accuracy of conventional periapical radiography with detailed zonography using the Scanora system for the detection of periodontal disease. METHODS: We selected for comparison 311 periodontal sites in 165 patients. Five observers independently assessed the periapical radiographs and detailed zonograms for marginal widening of periodontal ligament space, crestal erosion, vertical bone loss, furcation involvement and calculus. RESULTS: ROC analysis revealed no significant differences between the two imaging techniques for either overall or lesion-specific interpretation of periodontal pathology. The sensitivity of periapical radiography was 79%, and of detailed zonography 91% (multiview) and 89% (stereoscopic). Specificities were 82%, 77% and 83%, respectively. CONCLUSION: Detailed zonography performs as well as periapical radiography in the detection of periodontal disease.

A comparison of detailed zonography with periapical radiography for the detection of periapical lesions.

The diagnostic accuracy of detailed zonography using the Scanora multimodal X-ray system was compared with that of periapical radiography. The study was based on the detection of periapical bone lesions at 259 dental sites distributed evenly throughout the dentitions of 164 patients. Each site was examined by periapical radiography and zonography, in parallel. The zonograms consisted of four detailed images that could also be read as stereopairs, in either the horizontal or vertical direction. Five observers evaluated the sites for the presence or absence of periapical osteolysis or sclerosis and apical widening of the periodontal ligament space for the whole dentition, and for three dental regions. ROC analysis revealed no significant overall or regional differences between the diagnostic accuracies of the periapical and zonographic techniques, regardless of whether the zonograms were read as sets of four images (multiview) or stereoscopic images. The sensitivity of periapical radiography was 72%, that of multiview zonography 88%, and that of stereoscopic zonography 85%. Specificities were 93%, 84% and 89%, respectively. The energy imparted during detailed zonography was 0.98 mJ. It is concluded that zonography is as good as periapical radiography for the detection of periapical pathology.

Comparison of periapical and detailed narrow-beam radiography for diagnosis of periodontal pathology.

The diagnostic performance of the detailed narrow-beam (DNB) technique of the Scanora multimodal X-ray system was compared with periapical radiography for detecting periodontal pathology. In total, 253 sites in 133 patients were examined. Receiver operating characteristics (ROC) of both imaging modalities were analyzed in relation to the ratings of five observers for the whole dentition, three dental regions and five types of periodontal lesion. ROC analysis demonstrated that the overall diagnostic performance of DNB radiography was better (P < 0.05) than that of periapical radiography. DNB radiography was significantly superior (P < 0.01) for detecting marginal widening of periodontal membrane space, but there was no significant difference between the two techniques for crestal erosion, vertical bone loss, furcation involvement or calculus. The regional differences found in overall diagnostic performance of the two imaging modalities were not significant. The sensitivity for periapical radiography was 71% and for DNB radiography 85%, and the specificities 82% and 81% respectively. It is concluded that DNB radiography is a good radiographic examination for periodontal disease, and an acceptable alternative to periapical radiography.

Comparison of periapical and detailed narrow-beam radiography for diagnosis of periapical bone lesions.

The diagnostic performance of the detailed narrow-beam (DNB) technique of the Scanora multimodal radiography system was compared for periapical radiography for the detection of periapical bone lesions at 262 dental sites in 144 patients. Receiver operating characteristics (ROC) of both imaging modalities were analysed in relation to the ratings of five observers for the whole dentition, three dental regions, and two types of periapical lesions. ROC analysis demonstrated no overall or regional significant differences in the diagnostic performance of the two imaging modalities. The sensitivity for periapical radiography was 72% and for DNB radiography 90%, and the specificities 89% and 88%, respectively. It is concluded that DNB radiography performs as well as periapical radiography for detecting periapical bone lesions.

Stereographic assessment of mandibular canal in relation to the roots of impacted lower third molar using multiprojection narrow beam radiography.

The position of the mandibular canal in relation to the superimposed roots of 173 impacted lower 3rd molars was evaluated radiologically. A multiprojection narrow beam radiography (MNBR) technique recently developed for oral radiography was applied in this study. This method enables stereoscopic examination of the area of interest. The mandibular canal was located bucally to the roots of 105 (61%) teeth, lingually to the roots of 57 (33%) teeth, and between the roots of 6 (3%) teeth. The relationship of canal to roots of 5 (3%) teeth was not possible to determine. Disagreement between radiological assessment and clinical observation was found in 4 (5%) of 80 operated teeth. The canal was visible at operation in 23 (29%) cases, which was predicted at stereographic examination in 21 (91%) cases. The MNBR stereographic technique is a useful method with high sensitivity (0.83) for evaluating the bucco-lingual relationship of the mandibular canal to the roots of a 3rd molar.

Comprehensive oral X-ray diagnosis: Scanora multimodal radiography. A preliminary description.

Scanora (Soredex, Orion Corporation, Helsinki, Finland) is a multimodal radiography system which utilizes the principles of narrow beam radiography and spiral tomography. The system includes an integrated multifunction X-ray unit, a coordinate system for object localization and a wide selection of dental and maxillofacial imaging problems. All imaging procedures are computer controlled and executed automatically. Clinical experience and preliminary results show that the multimodal imaging system has great potential in the detection of pathological conditions of the maxillofacial region.

Use of orthopantomographs in forensic identification.

Radiographs of the head region were used for identification of 17 victims during an 11-year period in the Department of Forensic Medicine, University of Turku, Finland. Examinations resulted in positive identification of 10 victims. Proof of identity of four people was based on exclusion identifications. In one case, comparable information supporting the identity was achieved. Due to insufficient ante- and postmortem material, two individuals remained unidentified by radiological methods. The use of orthopantomography in identification is recommended because it enables visualization of the structures of the jaws and related areas on a single radiograph.

Multimodal radiography: a new imaging technique and system for oral diagnosis.

The multimodal radiography system is based on the combined use of narrow-beam radiography and spiral tomography in one set of equipment. The essentials of a system are a multifunction unit, preprogrammed imaging procedures for various dentomaxillofacial objects and a co-ordinate system for object location. Four years of clinical experience have shown that multimodal radiography is effective for depicting dentomaxillofacial structures for diagnostic purposes. The detailed narrow beam imaging mode of multimodal radiography has also been compared with intraoral radiography as regards their abilities to reveal periodontal and periapical lesions. Preliminary results indicate that detailed narrow beam radiography is more accurate than intraoral radiography in the diagnosis of periodontal and periapical pathology.