Arrested eruption of the permanent lower second molar. (1/342)

The incidence of retention/impaction of the permanent lower second molar (M2inf) lies between 0.6/1000 and 3/1000. Therefore, the purpose of the present study was to investigate the craniofacial morphology, the frequency of dental anomalies and the inclination of the affected M2inf and the adjacent first molar in patients with arrested eruption of M2inf. The overall goal was to elucidate the aetiology of arrested tooth eruption and to present the characteristics of these patients in order to improve diagnosis and treatment planning. Radiographic material (profile radiographs and orthopantomograms) from 19 patients (nine females and 10 males; 13-19 years of age at the time of referral) were analysed. The ages of the patients when profile radiographs were taken for cephalometric analysis varied from 8 to 16 years. The study shows that this group of patients, compared with a reference group, had an increased sagittal jaw relationship (Class II). Specifically, the mandibular prognathism was less, the mandibular gonial angle smaller, the mandibular alveolar prognathism enlarged and the maxillary incisor inclination less than in the reference group. Furthermore, this group of patients had a more frequent occurrence of morphological tooth anomalies, such as root deflections, invaginations, and taurodontism. However, none of the patients with arrested eruption of M2inf had agenesis of the lower third molar. The study did not reveal an association between the degree of inclination of the M2inf and that of the first molar in the same region. The results of this investigation show that conditions such as the craniofacial morphology and deviations in the dentition are associated with arrested eruption of M2inf. Therefore, it is important to evaluate these conditions in future diagnosis and treatment planning of patients with arrested eruption of M2inf.  (+info)

Imaging of a Stafne bone cavity: what MR adds and why a new name is needed. (2/342)

Stafne bone cavities are asymptomatic radiolucencies seen at the angle of the mandible. Although plain films are often sufficient for diagnosis, confirmatory imaging is needed in atypical cases. We describe the MR imaging findings of a Stafne bone cavity, describe the contents, explain why a new name is needed, and discuss the relative merits of different radiologic techniques for establishing this diagnosis.  (+info)

Efficacy of mandibular topical anesthesia varies with the site of administration. (3/342)

This study compared the threshold of pain sensitivity in the anterior mandibular mucobuccal fold with the posterior. This was followed by a comparison of the reduction of needle insertion pain in the anterior mucobuccal fold and the pterygo-temporal depression by either topical anesthesia or nitrous oxide inhalation. The pain threshold was determined by an analgometer, a pain-measuring device that depends on pressure readings; additionally, pain caused by a needle inserted by a normal technique was assessed using a visual analog scale (VAS). The threshold of pain was significantly lower in the incisor and canine regions than in the premolar and the molar regions (P < 0.001). Compared to a placebo, topical anesthesia significantly reduced the pain from needle insertion in the mucobuccal fold adjacent to the mandibular canine (P < 0.001), but did not significantly reduce pain in the pterygotemporal depression. The addition of 30% nitrous oxide did not significantly alter pain reduction compared to a control of 100% oxygen. These results suggest that topical anesthesia application may be effective in reducing the pain of needle insertion in the anterior mandibular mucobuccal fold, but may not be as effective for a standard inferior alveolar nerve block. The addition of 30% nitrous oxide did not lead to a significant improvement.  (+info)

Mandibular shape and skeletal divergency. (4/342)

Pre-treatment lateral cephalograms of 41 skeletal Class I girls aged 11 to 15 were divided according to MP-SN angle: lower than 28 degrees (hypodivergent, 10 girls), between 31 and 34 degrees (normodivergent, 18 girls), or larger than 37 degrees (hyperdivergent, 13 girls). The mandibular outlines were traced and digitized, and differences in shape were quantified using the elliptic Fourier series. Size differences were measured from the areas enclosed by the mandibular outlines. Shape differences were assessed by calculating a morphological distance (MD) between the size-independent mean mathematical reconstructions of the mandibular outlines of the three divergency classes. Mandibular shape was different in the three classes: large variations were found in hyperdivergent girls versus normodivergent girls (MD = 4.61), while smaller differences were observed in hypodivergent girls (MD versus normodivergent 2.91). Mean size-independent mandibular shapes were superimposed on an axis passing through the centres of gravity of the condyle and of the chin. Normodivergent and hyperdivergent mandibles differed mostly at gonion, the coronoid process, sigmoid notch, alveolar process, posterior border of the ramus, and along the mandibular plane. A significant size effect was also found, with smaller mandibles in the hyperdivergent girls.  (+info)

Neural modulation of inflammatory reactions in dental tissues incident to orthodontic tooth movement. A review of the literature. (5/342)

This article reviews the current knowledge of the biological aspects of dental tissue changes incident to orthodontic tooth movement. The inflammatory nature of these tissue changes was first recognized in the early 1970s, and since then a number of morphological and quantitative investigations have been published in support of this view. The studies dealing with vascular and cellular dental tissue changes, as well as those concerned with inflammatory mediators present at sites of orthodontic tooth movement are systematized and presented accordingly. Special emphasis is placed upon the role of the sensory nerve fibres and their neuropeptides in the control, and development of an inflammatory process, i.e. their role in tooth movement.  (+info)

Osteometry of the mandible performed using dental MR imaging. (6/342)

BACKGROUND AND PURPOSE: On cross-sectional and panoramic reformatted images from axial (dental) CT scans of the mandible it may be difficult to identify the inferior alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of the mandibular canal. Dental MR images are comparable to dental CT scans, which directly show the IANB; however, measurements of length may not be reliable owing to susceptibility artifacts and field inhomogeneities in the oral cavity. Therefore, the accuracy of length measurements on dental MR images was compared with that on dental CT scans and direct osteometry. METHODS: Dental T1-weighted MR imaging using a high-resolution turbo gradient-echo sequence and dental CT were performed in six anatomic specimens. The axial scans were reformatted as panoramic and cross-sectional reconstructions on a workstation and characteristic cross sections were obtained from all mandibles. The longest axis in the bucco-lingual and apico-basal directions, the distances from the top of the mandibular canal to the top of the alveolar ridge and from the bottom of the mandibular canal to the base of the mandible, and the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on the cross sections and compared with measurements on corresponding MR and CT reformatted images. RESULTS: The correlation between direct osteometry and dental MR and CT was strong, except for the bone cortex diameter at the top of the alveolar ridge, where only a moderate correlation was found. Means of comparable length measurements were not significantly different among the three methods. CONCLUSION: The accuracy of length measurements in the jaw bones obtained using dental MR is comparable to that of dental CT and is not significantly different from direct osteometry. Thus, dental MR is a potential alternative to CT for dental imaging.  (+info)

A 5-year post-operative review of secondary alveolar bone grafting in the Yorkshire region. (7/342)

The objective of this study was to determine the quality of secondary alveolar bone grafting in the Yorkshire region, and consisted of a retrospective review of patients case notes and radiographs at five surgical units within the Yorkshire region. The subjects were 109 patients who had secondary alveolar bone grafting between 1.9.91. and 31.8.96. The quality of outcome was assessed using a four-point radiographic scale from occlusal radiographs taken at least 3 months post-operatively: Grade 1 = > 75 per cent bony in-fill, Grade 2 = 50-75 per cent bony in-fill, Grade 3 = < 50 per cent bony in-fill, and Grade 4 = no bony bridge. The radiographic assessment scale was assessed for reliability: inter-examiner weighted kappa = 0.622-0.715 and intra-examiner = 0.818-0.943. Grade 1 results were achieved in 63.2 per cent patients receiving orthodontic expansion and in 40 per cent without expansion before grafting. The four-point radiographic scale described is a useful tool in assessing alveolar bone grafting, Orthodontic expansion.  (+info)

Blood vessel response to pan-endothelium (RECA-1) antibody in normal and tooth loaded rat periodontal ligament. (8/342)

Immunolabelling of the normal rat molar periodontal ligament (PDL) with RECA-1 antibody, an endothelial cell surface marker, demonstrated the endothelium in the different categories of blood vessels. The intensity of immunolabelling was similar for venous capillaries (VC), post-capillary-sized venules (PCV), and collecting venules (CV). Arterial capillaries (AC) and terminal arterioles (TA) showed a different response, both having a high intensity of endothelium and smooth muscle cell labelling, whether they were located in the PDL or alveolar bone. An experimental, continuous loading of approximately 100 g was applied unilaterally to the mandibular molars for 10 minutes. In the PDL apical compression zone this load resulted in a loss of RECA-1 immunolabelling of the VC, PCV, and CV. Adjacent to the alveolar crest, where shear and tension loads were judged to have occurred, there was enhanced immunoreactivity of VC, PCV, and CV. In the loaded PDL, the AC and TA, irrespective of their location in the ligament or bone, showed strong immunofluorescence of their endothelium and the enveloping smooth muscle layer. Vessel and PDL immunofluorescence were analysed with standardized grey scale densitometry, and the data subjected to ANOVA. Comparison between individual vessel means showed significant differences (P < 0.05). Control teeth showed no immunostaining difference between the coronal and apical region vessels, whereas in the loaded teeth the overall cervical vessel endothelium had a significantly higher value than the apical vessel endothelium (P < 0.001). These findings demonstrate that the endothelium of this microvascular bed can undergo significant immunoreactivity changes when exposed to short-term, continuous, tooth loading.  (+info)

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