Wnt/ß-catenin Signaling Controls Maxillofacial Hyperostosis.

The roles of Wnt/ß-catenin signaling in regulating the morphology and microstructure of craniomaxillofacial (CMF) bones was explored using mice carrying a constitutively active form of ß-catenin in activating Dmp1-expressing cells (e.g., daßcatOt mice). By postnatal day 24, daßcatOt mice exhibited midfacial truncations coupled with maxillary and mandibular hyperostosis that progressively worsened with age. Mechanistic insights into the basis for the hyperostotic facial phenotype were gained through molecular and cellular analyses, which revealed that constitutively activated ß-catenin in Dmp1-expressing cells resulted in an increase in osteoblast number and an increased rate of mineral apposition. An increase in osteoblasts was accompanied by an increase in osteocytes, but they failed to mature. The resulting CMF bone matrix also had an abundance of osteoid, and in locations where compact lamellar bone typically forms, it was replaced by porous, woven bone. The hyperostotic facial phenotype was progressive. These findings identify for the first time a ligand-independent positive feedback loop whereby unrestrained Wnt/ß-catenin signaling results in a CMF phenotype of progressive hyperostosis combined with architecturally abnormal, poorly mineralized matrix that is reminiscent of craniotubular disorders in humans.

Molecular Basis for Craniofacial Phenotypes Caused by Sclerostin Deletion.

Some genetic disorders are associated with distinctive facial features, which can aid in diagnosis. While considerable advances have been made in identifying causal genes, relatively little progress has been made toward understanding how a particular genotype results in a characteristic craniofacial phenotype. An example is sclerosteosis/van Buchem disease, which is caused by mutations in the Wnt inhibitor sclerostin (SOST). Affected patients have a high bone mass coupled with a distinctive appearance where the mandible is enlarged and the maxilla is foreshortened. Here, mice carrying a null mutation in Sost were analyzed using quantitative micro-computed tomographic (µCT) imaging and histomorphometric analyses to determine the extent to which the size and shape of craniofacial skeleton were altered. Sost-/- mice exhibited a significant increase in appositional bone growth, which increased the height and width of the mandible and reduced the diameters of foramina. In vivo fluorochrome labeling, histology, and immunohistochemical analyses indicated that excessive bone deposition in the premaxillary suture mesenchyme curtailed overall growth, leading to midfacial hypoplasia. The amount of bone extracellular matrix produced by Sost-/- cells was significantly increased; as a consequence, osteoid seams were evident throughout the facial skeleton. Collectively, these analyses revealed a remarkable fidelity between human characteristics of sclerosteosis/van Buchem disease and the Sost-/- phenotype and provide clues into the conserved role for sclerostin signaling in modulating craniofacial morphology.

Effects of laser etching on shear bond strengths of brackets bonded to fluorosed enamel.

AIM: To evaluate the effects of laser etching on the shear bond strengths (SBS) and failure modes of brackets bonded to fluorosed enamel. MATERIALS AND METHODS: This in vitro study included 34 fluorosed and 34 nonfluorosed teeth. Teeth were divided into four subgroups according to the etching procedure: Group (A) normal enamel etched with 37% phosphoric acid for 15 s, Group (B) nonfluorosed enamel etched with erbium:yttrium aluminum garnet (Er: YAG) laser for 15 s, Group (C) fluorosed enamel etched with 37% phosphoric acid for 30 s, Group (D) fluorosed enamel etched with Er: YAG laser for 30 s. After bonding of the premolar metal brackets, specimens were subjected to the thermal cycles. After SBS test, modified adhesive remnant index (ARI) by using stereomicroscope and failure modes with a scanning electron microscope (SEM) was determined. After bonding, one specimen from each group was examined under SEM to identify enamel-resin interfaces. ANOVA and Tukey post-hoc tests were used to compare the SBS values. The Kruskal-Wallis and Chi-square tests were used to analyze the distribution of ARI scores and failure modes of groups. RESULTS: The highest mean SBS value (17.56 ± 1.05 MPa) was found in Group A, while the lowest (12.25 ± 0.96 MPa) in Group D. Significant differences were found in the SBS test and failure modes among all groups. The differences between ARI scores of the groups were not significant. CONCLUSION: According to our findings, laser etching reduced the SBS of brackets bonded to fluorosed teeth, but provided clinically acceptable SBS values.

Comparison of the effects of rapid maxillary expansion and surgically assisted rapid maxillary expansion in the sagittal, vertical, and transverse planes.

OBJECTIVE: The aim of this study was to evaluate and compare the effects of rapid maxillary expansion (RME) and surgically assisted RME (SARME) in the sagittal, vertical, and transverse planes. STUDY DESIGN: Orthodontic records of 28 patients were selected retrospectively and divided into two treatment groups. Group 1 comprised 14 patients (4 boys, 10 girls, mean age 14.2 ± 0.74 years) who had been treated with RME. Group 2 comprised 14 patients (4 boys, 10 girls, mean age 19.6 ± 2.73 years) who had been treated with SARME. Measurements were performed on lateral and posteroanterior cephalograms and dental casts obtained before (T0) and after (T1) expansion. RESULTS: Statistically significant differences were found in soft tissue convexity angle, anterior face height, and upper nasal width in group 1, and in U1-NA length and posterior face height measurements in group 2 (P<.05). In both groups significant increases were found in interpremolar, intermolar, maxillary, and lower nasal widths and in anterior lower face height (P<.01). Statistically significant intergroup differences were found in the ANB angle (P<.05) and maxillary intercanine (P<.01) measurements. CONCLUSION: With both RME and SARME, successful expansion of maxillary dentoalveolar structures and nasal cavity and palatal widening were achieved. Sagittal plane effects of SARME were similar to those of RME on dental skeletal and airway measurements.

A non-syndrome case with bilateral supernumerary canines: report of a rare case.

Supernumerary teeth are described as the teeth formed in excess of the normal dental formula. Prevalence of supernumerary teeth varies between 0.1% and 3.8% in general Caucasian population. They have been reported in both the primary and the permanent dentition. Supernumerary teeth may occur in any region of the dental arch. However, a supernumerary tooth in the canine region is a rare condition and to our knowledge, a non-syndrome case with bilateral supplemental maxillary canines did not exist in the literature. It was the aim of this report to evaluate this rare case in view of both oral radiology and orthodontics.

Prevalence of tooth transpositions and associated dental anomalies in a Turkish population.

OBJECTIVES: The aims of this study were to determine the prevalence of tooth transposition in a Turkish population, possibly associated dental anomalies and whether side laterality, gender expression or genetic influence exist or not. METHODS: Panoramic radiographs of 5486 patients referred to Department of Oral Diagnosis and Radiology, University of Suleyman Demirel between April 2003 and March 2004 were examined retrospectively. All patients with tooth transpositions were recalled for detailed clinical examination and medical history. Age, sex, history (trauma), location of transposition, and associated congenital dental anomalies were recorded with details. RESULTS: 22 transpositions were found in 21 of 5486 (0.38%) patients. The most frequently seen transposition was maxillary canine-lateral incisor (1.64/1000), secondly maxillary canine-first premolar (0.91/1000) and maxillary canine-second premolar (0.18/1000) was the least frequently seen one. The frequencies of right and left side occurrence were equal (11/11). Each sex was affected similarly (11 males, 10 females). CONCLUSIONS: The prevalence of tooth transposition was 0.38% in a Turkish population. Maxillary canine-lateral incisor transposition was found to have a higher frequency than maxillary canine-first premolar transposition. Maxillary canine-second premolar transposition that had not been previously reported in the literature was observed in one of our cases. Transpositions had similar frequencies in both sexes.

Correlation between eminence steepness and condyle disc movements in temporomandibular joints with internal derangements on magnetic resonance imaging.

A steep articular eminence is reported to be a predisposing factor for the development of disc displacement. The purpose of this study was to evaluate the biomechanics of the temporomandibular joint (TMJ) in internal derangements and, additionally, to investigate whether a relationship exists between the steepness of the articular eminence and disc displacement, with (DDR) and without reduction (DDWR). The material consisted of the sagittal TMJ magnetic resonance images (MRIs) of 39 joints (26 DDR and 13 DDWR). Sagittal and coronal TMJ MRIs were obtained at maximum inter-cuspation and in the maximum mouth-opening position. The steepness of the articular eminence, disc, and condyle rotation, and condyle translation were investigated. A Student's t-test was performed and correlation coefficients calculated. The results revealed an increase in disc rotation in the DDR group and in condyle translation in the DDWR group (P < 0.01). Condyle rotation and the steepness of the articular eminence were similar in both groups. Disc rotation was positively correlated with condyle rotation and negatively correlated with condyle translation in the DDR group (P < 0.05, r = 0.44). Condyle translation was positively correlated with steepness of the articular eminence in the DDWR group (P < 0.01, r = 0.74). There was no correlation between movements of the disc-condyle assembly and the steepness of the articular eminence in the DDR group. Nevertheless, a relationship between condyle translation and the steepness of the articular eminence was found in the DDWR subjects.

Hazards of orthodontics appliances and the oropharynx.

Occasionally orthodontic appliances or parts of orthodontic appliances have caused problems with either the airway or the gastrointestinal tract. The type of appliances that have caused problems and their clinical management are discussed. A case is described in which an upper removable appliance with inadequate retention became lodged in a patient's pharynx lacerating the palatine tonsils. Suggestions are made to try and avoid the problems that were encountered in this case and others reported in the literature in patients undergoing orthodontic treatment.

Changes in position of the temporomandibular joint disc and condyle after disc repositioning appliance therapy: a functional examination and magnetic resonance imaging study.

Disc-repositioning splints are routinely used in the treatment of anteriorly displaced discs. The rationale of these appliances is to direct the mandibular condyle anteriorly in the glenoid fossa and to recapture the disc onto the condyle. The stability of disc recapture depends on reestablishment of the occlusion and the adaptive capabilities of the temporomandibular joint. It could therefore be suggested that treatment success is potentially higher in the active growth period. In this case report, partial disc recapture was observed on magnetic resonance images after application of a maxillary disc-repositioning appliance. Orthodontic treatment was applied for the retention of disc recapture.