Mithran Goonewardene

Morphologic changes of the palate after rapid maxillary expansion: A 3-dimensional computed tomography evaluation

INTRODUCTION The purpose of this retrospective study was to estimate the area change of the palate after rapid maxillary expansion (RME) in the early mixed dentition stage by using a 3-dimensional (3D) helical computed tomography (CT) scanning technique. In addition, linear changes in the maxillary arch were evaluated. METHODS The treated sample consisted of 43 children (mean age, 9 years 1 month) treated with a bonded RME appliance. The untreated control group consisted of 7 children (mean age, 9 years 3 months). Pretreatment and posttreatment dental casts were evaluated by using 3D helical CT scanning procedures. The Student t test was used to compare the linear, area, and angular differences between the treatment times. RESULTS RME produced clinically significant increases in interdental widths across the canines, the deciduous first molars, and the permanent first molars in the maxillary arch. Significant increases in cross-sectional area were observed across the permanent first molars (15.3 mm(2)). There was marked variability in the buccal tipping of the permanent first molars. CONCLUSIONS Three-dimensional helical CT scanning is an accurate and cost-effective method of assessing dental cast morphologic changes. It can also provide fast and accurate data acquisition and subsequent analysis.

Accuracy of a LeFort I maxillary osteotomy

An optimal outcome of combined surgery and orthodontics involving the maxilla is dependent on many factors. Accurate placement of the maxilla by the surgical team is ultimately of paramount importance. The aim of this retrospective study was to evaluate the accuracy of LeFort I maxillary osteotomy with respect to the presurgical prediction. The sample comprised 42 patients (33 females, nine males) who had undergone LeFort I osteotomy procedure alone or in combination with a mandibular osteotomy with or without genioplasty. Tracings of presurgical and immediate postsurgical lateral cephalograms and surgical predictions were digitized and compared using Quick Ceph software analysis. Vertical and horizontal measurements to various skeletal landmarks were used to assess the discrepancy between the predicted maxillary position and the actual postsurgical result. Statistically significant differences were found between the predicted and actual postsurgical maxillary molar vertical position, and significant differences were also found for the palatal plane angular measurements. Two surgical teams were compared, and surgical team 1 had significantly less variation in the surgical outcomes than did surgical team 2. When single-jaw and bimaxillary surgery were compared, no significant differences were found. Similarly, there were no statistically significant differences found when assessing the primary direction of movement (impaction vs downgraft vs advancement). Overall, 66% of the results were within two mm of prediction and 26% of the results were within one mm of prediction. A LeFort I maxillary osteotomy can be an accurate procedure with a wide range of discrepancy.

A histological and micro-CT investigation in to the effect of NGF and EGF on the periodontal, alveolar bone, root and pulpal healing of replanted molars in a rat model - a pilot study

BackgroundThis study aims to investigate, utilising micro-computed tomography (micro-CT) and histology, whether the topical application of nerve growth factor (NGF) and/or epidermal growth factor (EGF) can enhance periodontal, alveolar bone, root and pulpal tissue regeneration while minimising the risk of pulpal necrosis, root resorption and ankylosis of replanted molars in a rat model.MethodsTwelve four-week-old male Sprague-Dawley rats were divided into four groups: sham, collagen, EGF and NGF. The maxillary right first molar was elevated and replanted with or without a collagen membrane impregnated with either the growth factors EGF or NGF, or a saline solution. Four weeks after replantation, the animals were sacrificed and the posterior maxilla was assessed using histological and micro-CT analysis. The maxillary left first molar served as the control for the corresponding right first molar.ResultsMicro-CT analysis revealed a tendency for all replanted molars to have reduced root length, root volume, alveolar bone height and inter-radicular alveolar bone volume. It appears that the use of the collagen membrane had a negative effect while no positive effect was noted with the incorporation of EGF or NGF. Histologically, the incorporation of the collagen membrane was found to negatively affect pulpal, root, periodontal and alveolar bone healing with pulpal inflammation and hard tissue formation, extensive root resorption and alveolar bone fragmentation. The incorporation of EGF and NGF did not improve root, periodontal or alveolar bone healing. However, EGF was found to improve pulp vascularisation while NGF-improved pulpal architecture and cell organisation, although not to the level of the control group.ConclusionsResults indicate a possible benefit on pulpal vascularisation and pulpal cell organisation following the incorporation of EGF and NGF, respectively, into the alveolar socket of replanted molars in the rat model. No potential benefit of EGF and NGF was detected in periodontal or root healing, while the use of a collagen membrane carrier was found to have a negative effect on the healing response.

Monitoring dental pulp sensibility and blood flow in patients receiving mandibular orthognathic surgery

AIM To investigate the effect of orthognathic surgery, in particular genioplasty, on pulp sensibility and pulp blood flow (PBF). METHODOLOGY Pulp blood flow monitoring and CO(2) pulp sensibility testing were performed on 101 mandibular anterior teeth from 17 subjects who received mandibular bilateral sagittal split osteotomy (BSSO) with or without genioplasty and other maxillary surgical procedures combined with orthodontic treatment. A laser Doppler flowmeter was used to monitor PBF using customized acrylic splints for each subject. Preoperative baseline scores were recorded from up to 1 week preoperatively, and subsequently monitored for up to 18-28 weeks postoperatively. The data were analysed by RMANOVA and pairwise comparisons. Statistical significance was defined as P < 0.05. RESULTS The average PBF in subjects who received genioplasty was not significantly different to those who received no genioplasty (F = 0.076, P = 0.784). In both groups, PBF decreased significantly postoperatively (F = 23.323, P = 0.000) and remained significantly lower (P = 0.000) than preoperative values at all times. PBF decreased markedly for 1-2 weeks postoperatively in patients who received genioplasty. However, there were no statistical differences between the PBF values at any time postoperatively for either group (P > 0.05). All teeth in both groups responded to CO(2) preoperatively. The average number of teeth that responded to CO(2) postoperatively in the genioplasty group was lower without significant difference when compared to the group without genioplasty (binomial distribution F = 2.63, P = 0.1256, normal distribution F = 2.98, P = 0.1048). At each progressive period after 1-2 weeks following surgery, the number of teeth responding to CO(2) increased significantly (P < 0.001) in both groups. At the end of the study, in the genioplasty group 81.1% of teeth responded to CO(2) compared to all teeth in the group without genioplasty. CONCLUSION Pulp blood flow decreased and remained significantly lower than preoperative values in mandibular anterior teeth postoperatively with or without genioplasty. At no time was the absence of PBF recorded. The number of teeth that responded to CO(2) decreased markedly postoperatively but recovered significantly over time. All teeth regained sensibility in the group without genioplasty at the end of the study. There were neither common trends nor coincidence in the recovery of PBF and pulp sensibility.

Numerical simulation of pharyngeal airflow applied to obstructive sleep apnea: effect of the nasal cavity in anatomically accurate airway models

Repetitive brief episodes of soft-tissue collapse within the upper airway during sleep characterize obstructive sleep apnea (OSA), an extremely common and disabling disorder. Failure to maintain the patency of the upper airway is caused by the combination of sleep-related loss of compensatory dilator muscle activity and aerodynamic forces promoting closure. The prediction of soft-tissue movement in patient-specific airway 3D mechanical models is emerging as a useful contribution to clinical understanding and decision making. Such modeling requires reliable estimations of the pharyngeal wall pressure forces. While nasal obstruction has been recognized as a risk factor for OSA, the need to include the nasal cavity in upper-airway models for OSA studies requires consideration, as it is most often omitted because of its complex shape. A quantitative analysis of the flow conditions generated by the nasal cavity and the sinuses during inspiration upstream of the pharynx is presented. Results show that adequate velocity boundary conditions and simple artificial extensions of the flow domain can reproduce the essential effects of the nasal cavity on the pharyngeal flow field. Therefore, the overall complexity and computational cost of accurate flow predictions can be reduced.

A novel molecule, SLURP‐1, enhances the survival of periodontal ligament fibroblasts

BACKGROUND AND OBJECTIVE The mechanism behind the survival of periodontal ligament fibroblasts is critical for the maintenance of periodontal ligament tissue. However, the number of known proteins that are involved in this action is limited. The aim of this study was to examine the role of a novel molecule, secreted mammalian Ly-6/urokinase-type plasminogen activator receptor-related protein 1 (SLURP-1), in periodontal ligament fibroblast survival. MATERIAL AND METHODS Human periodontal ligament fibroblasts were isolated from eight healthy human donors using established protocols. Gene expression for SLURP-1 was analysed using the reverse transcriptase-polymerase chain reaction, while protein expression was examined by immunoblotting with a SLURP-1 antibody. In addition, the apoptotic effect was examined using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. RESULTS Messenger RNA for SLURP-1 was expressed in the periodontal ligament, gingival fibroblasts, oral keratinocytes and bone. Moreover, the protein was secreted by both periodontal ligament and gingival fibroblasts. Functional analysis revealed that SLURP-1 substantially enhanced cell survival in periodontal ligament fibroblasts by the anti-apoptotic signal phosphatidylinositol 3-kinase. CONCLUSION These findings suggest that SLURP-1 may play an important role in the control and maintenance of the periodontal ligament by protecting the periodontal ligament fibroblasts from apoptosis.

Sexually dimorphic facial features vary according to level of autistic-like traits in the general population.

BackgroundIn a recent study, Bejerot et al. observed that several physical features (including faces) of individuals with an autism spectrum disorder (ASD) were more androgynous than those of their typically developed counterparts, suggesting that ASD may be understood as a ‘gender defiant’ disorder. These findings are difficult to reconcile with the hypermasculinisation account, which proposes that ASD may be an exaggerated form of cognitive and biological masculinity. The current study extended these data by first identifying six facial features that best distinguished males and females from the general population and then examining these features in typically developing groups selected for high and low levels of autistic-like traits.MethodsIn study 1, three-dimensional (3D) facial images were collected from 208 young adult males and females recruited from the general population. Twenty-three facial distances were measured from these images and a gender classification and scoring algorithm was employed to identify a set of six facial features that most effectively distinguished male from female faces. In study 2, measurements of these six features were compared for groups of young adults selected for high (n = 46) or low (n = 66) levels of autistic-like traits.ResultsFor each sex, four of the six sexually dimorphic facial distances significantly differentiated participants with high levels of autistic-like traits from those with low trait levels. All four features were less masculinised for high-trait males compared to low-trait males. Three of four features were less feminised for high-trait females compared to low-trait females. One feature was, however, not consistent with the general pattern of findings and was more feminised among females who reported more autistic-like traits. Based on the four significantly different facial distances for each sex, discriminant function analysis correctly classified 89.7% of the males and 88.9% of the females into their respective high- and low-trait groups.ConclusionsThe current data provide support for Bejerot et al.’s androgyny account since males and females with high levels of autistic-like traits generally showed less sex-typical facial features than individuals with low levels of autistic-like traits.

Facial asymmetry assessment in adults using three-dimensional surface imaging.

BackgroundThe use of three-dimensional (3D) surface imaging is becoming more popular and accepted in the fields of Medicine and Dentistry. The present study aims to develop a technique to automatically localise and quantify soft-tissue asymmetry in adults using 3D facial scans. This may be applied as a diagnostic tool to monitor growth and dynamic changes and to evaluate treatment outcomes.Methods3D facial surface data were captured from 55 adults comprising 28 symmetrical faces and 27 asymmetrical faces using a 3dMDface system. A landmark-independent method, which compared the original and the mirrored 3D facial data, was developed to quantify the asymmetry. A Weibull distribution-based probabilistic model was generated from the root-mean-square (RMS) error data for the symmetrical group to designate a level of asymmetry which represented a normal range.ResultsStatistically significant (p < 0.0001) differences in the RMS error values were found when comparing symmetrical with asymmetrical groups and a similarly significant difference was identified between the lower and the upper face of the asymmetrical group.ConclusionsThe proposed 3D imaging-based method of identifying and quantifying facial soft-tissue asymmetry was fast and effective. The Weibull distribution-based comparison of a person’s asymmetry with respect to a large sample of symmetrical faces may also be used to evaluate growth, soft-tissue compensations and surgical outcomes.

Success rates of a skeletal anchorage system in orthodontics: A retrospective analysis

OBJECTIVES To evaluate the premise that skeletal anchorage with SAS miniplates are highly successful and predictable for a range of complex orthodontic movements. MATERIALS AND METHODS This retrospective cross-sectional analysis consisted of 421 bone plates placed by one clinician in 163 patients (95 female, 68 male, mean age 29.4 years ± 12.02). Simple descriptive statistics were performed for a wide range of malocclusions and desired movements to obtain success, complication, and failure rates. RESULTS The success rate of skeletal anchorage system miniplates was 98.6%, where approximately 40% of cases experienced mild complications. The most common complication was soft tissue inflammation, which was amenable to focused oral hygiene and antiseptic rinses. Infection occurred in approximately 15% of patients where there was a statistically significant correlation with poor oral hygiene. The most common movements were distalization and intrusion of teeth. More than a third of the cases involved complex movements in more than one plane of space. CONCLUSIONS The success rate of skeletal anchorage system miniplates is high and predictable for a wide range of complex orthodontic movements.

A review on three dimensional facial averaging for the assessment of orthodontic disorders

The introduction of rapid, non-invasive, and reproducible imaging technology such as three dimensional (3D) surface scanners, Cone Beam CT (CBCT) and low-dose CT have made it possible to develop tools for evaluating facial morphology and accurately planning dentofacial surgery. Facial averaging using 3D facial data is one such effective tool. This paper comprehensively reviews different techniques of facial averaging and their clinical applications. All the approaches are classified according to their methodologies and their scope and limitations are discussed. Future research directions are also identified.