Neelambar R. Kaipatur

Accuracy of Computer Programs in Predicting Orthognathic Surgery Hard Tissue Response

PURPOSE The aim of this systematic review was to investigate the accuracy of computer programs in predicting skeletal changes after orthognathic surgery. MATERIALS AND METHODS A systematic computerized database search was conducted with the help of a health sciences librarian. Specific selection criteria were used to select articles, reference lists of the selected articles were also searched for any potential articles that might have been missed in the electronic search, and additional information not available through the articles was obtained directly from the corresponding author. RESULTS Of the 79 initially identified articles (abstracts/titles), only 9 fulfilled the final selection criteria. As expected, no dental changes occurred but the computer programs were unable to precisely predict all the skeletal changes. Most of the prediction inaccuracies were within 2 mm or 2 degrees , which can be partially attributed to measurement errors in cephalometric tracing. CONCLUSIONS This systematic review showed that computer programs cannot consistently predict the skeletal changes occurring after orthognathic surgery but their results may be considered inside a clinically acceptable range. Last-minute changes by the surgeons could also explain the differences. We also conclude that no software program was shown to be superior in prediction accuracy compared with its competitor.

Basic and patient-oriented researchAccuracy of Computer Programs in Predicting Orthognathic Surgery Soft Tissue Response

PURPOSE The aim of the present systematic review is to investigate the accuracy of computer programs in predicting soft tissue response subsequent to skeletal changes after orthognathic surgery. MATERIALS AND METHODS A systematic computerized database search was conducted using Ovid Medline, Ovid Medline in-process and other nonindexed citations, all EBM reviews (including Cochrane DSR, ACP Journal, DARE, CCTR), Embase Experta Medica, Pascal, and Thomsens ISI Web of Science databases. The terms orthognathic surgery, orthodontic treatment, computer prediction, computer simulation, growth prediction, accuracy, precision, forecast, and human studies were used for the searches. The reference lists of all the selected articles were also searched for any potential articles that might have been missed in the electronic search of the database, and additional information not available through the articles was obtained directly from the source (by contacting the author). RESULTS Out of the 40 initially identified articles only 7 articles fulfilled the final selection criteria. All 7 studies in general showed accurate prediction outcomes (less than 2 mm) when compared with actual results in both horizontal and vertical directions. From all the available computer prediction programs Quick Ceph, DentoFacial Planner (DFP), and Computer-Assisted Simulation System for Orthognathic Surgery (CASSOS) were the most frequently used. CONCLUSIONS The most significant area of error in prediction through the available computer prediction programs was the lower lip area. Although the individual errors are almost always minimal (less than 2 mm), the composite addition of these minimal errors could have clinical implications.

Impact of bisphosphonate drug burden in alveolar bone during orthodontic tooth movement in a rat model: A pilot study

INTRODUCTION The aim of this pilot study was to investigate the effect of long-term bisphosphonate drug use (bone burden) on orthodontic tooth movement in a rat model. METHODS Sprague Dawley rats were used for orthodontic protraction of the maxillary first molars with nickel-titanium coil springs and temporary anchorage devices as anchorage. Four groups of 5 rats each were included in the study; the first 2 groups were dosed with alendronate or a vehicle during concurrent orthodontic tooth movement. The third and fourth groups were pretreated for 3 months with alendronate or vehicle injections, and bisphosphonate drug treatment was discontinued before orthodontic tooth movement. Tooth movement measurements were obtained at 0, 4, and 8 weeks using high-resolution in-vivo microcomputed tomography, and the tissues were analyzed with histology and dynamic labeling of bone turnover. RESULTS Appreciable tooth movement was achieved during the 8-week duration of this study with nickel-titanium coil springs and temporary anchorage devices. Both bisphosphonate treatment groups exhibited reduced tooth movement compared with the vehicle-dosed controls with a tendency toward more severe reduction in the bisphosphonate predosed group. Concurrent dosing of the bisphosphonate drug resulted in 56% and 65% reductions in tooth protraction at the 4-week and 8-week times, respectively. The impact of bisphosphonate bone burden in retarding tooth movement was even greater, with 77% and 86% reductions in tooth movement at 4 and 8 weeks, respectively. CONCLUSIONS In this study, we used a robust rat model of orthodontic tooth movement with temporary anchorage devices. It has provided evidence that the bone burden of previous bisphosphonate use will significantly inhibit orthodontic tooth movement.

RANKL release from self-assembling nanofiber hydrogels for inducing osteoclastogenesis in vitro

PURPOSE To develop a nanofiber hydrogel (NF-hydrogel) for sustained and controlled release of the recombinant receptor activator of NF-kB ligand; (RANKL) and to characterize the release kinetics and bioactivity of the released RANKL. METHODS Various concentrations of fluorescently-labelled RANKL protein were added to NF-hydrogels, composed of Acetyl-(Arg-Ala-Asp-Ala)4-CONH2 [(RADA)4] of different concentrations, to investigate the resulting in vitro release rates. The nano-structures of NF-hydrogel, with and without RANKL, were determined using atomic force microscopy (AFM). Released RANKL was further analyzed for changes in secondary and tertiary structure using CD spectroscopy and fluorescent emission spectroscopy, respectively. Bioactivity of released RANKL protein was determined using NFATc1 gene expression and tartrate resistant acid phosphatase (TRAP) activity of osteoclast cells as biomarkers. RESULTS NF-hydrogel concentration dependent sustained release of RANKL protein was measured at concentrations between 0.5 and 2%(w/v). NF-hydrogel at 2%(w/v) concentration exhibited a sustained and slow-release of RANKL protein up to 48h. Secondary and tertiary structure analyses confirmed no changes to the RANKL protein released from NF-hydrogel in comparison to native RANKL. The results of NFATc1 gene mRNA expression and TRAP activities of osteoclast, showed that the release process did not affect the bioactivity of released RANKL. CONCLUSIONS This novel study is the first of its kind to attempt in vitro characterization of NF-hydrogel based delivery of RANKL protein to induce osteoclastogenesis. We have shown the self-assembling NF-hydrogel peptide system is amenable to the sustained and controlled release of RANKL locally; that could in turn increase local concentration of RANKL to induce osteoclastogenesis, for application to the controlled mobilization of tooth movement in orthodontic procedures. STATEMENT OF SIGNIFICANCE Orthodontic tooth movement (OTM) occurs through controlled application of light forces to teeth, facilitating the required changes in the surrounding alveolar bone through the process of bone remodelling. The RANKL system regulates alveolar bone remodelling and controls root resorption during OTM. The use of exogenous RANKL to accelerate OTM has not been attempted to date because large quantities of RANKL for systemic therapy may subsequently cause serious systemic loss of skeletal bone. The controlled and sustained local release of RANKL from a carrier matrix could maximize its therapeutic benefit whilst minimizing systemic side effects. In this study a NF-hydrogel was used for sustained and controlled release of RANKL and the release kinetics and biofunctionality of the released RANKL was characterized. Our results provide fundamental insight for further investigating the role of RANKL NF-hydrogel release systems for inducing osteoclastogenesis in vivo.

A Novel Rat Model of Orthodontic Tooth Movement Using Temporary Skeletal Anchorage Devices: 3D Finite Element Analysis and In Vivo Validation

The aim of this animal study was to develop a model of orthodontic tooth movement using a microimplant as a TSAD in rodents. A finite element model of the TSAD in alveolar bone was built using μCT images of rat maxilla to determine the von Mises stresses and displacement in the alveolar bone surrounding the TSAD. For in vivo validation of the FE model, Sprague-Dawley rats (n = 25) were used and a Stryker 1.2 × 3 mm microimplant was inserted in the right maxilla and used to protract the right first permanent molar using a NiTi closed coil spring. Tooth movement measurements were taken at baseline, 4 and 8 weeks. At 8 weeks, animals were euthanized and tissues were analyzed by histology and EPMA. FE modeling showed maximum von Mises stress of 45 Mpa near the apex of TSAD but the average von Mises stress was under 25 Mpa. Appreciable tooth movement of 0.62 ± 0.04 mm at 4 weeks and 1.99 ± 0.14 mm at 8 weeks was obtained. Histological and EPMA results demonstrated no active bone remodeling around the TSAD at 8 weeks depicting good secondary stability. This study provided evidence that protracted tooth movement is achieved in small animals using TSADs.

High-Resolution Ultrasonic Imaging of Dento-Periodontal Tissues Using a Multi-Element Phased Array System.

Intraoral ultrasonography uses high-frequency mechanical waves to study dento-periodontium. Besides the advantages of portability and cost-effectiveness, ultrasound technique has no ionizing radiation. Previous studies employed a single transducer or an array of transducer elements, and focused on enamel thickness and distance measurement. This study used a phased array system with a 128-element array transducer to image dento-periodontal tissues. We studied two porcine lower incisors from a 6-month-old piglet using 20-MHz ultrasound. The high-resolution ultrasonographs clearly showed the cross-sectional morphological images of the hard and soft tissues. The investigation used an integration of waveform analysis, travel-time calculation, and wavefield simulation to reveal the nature of the ultrasound data, which makes the study novel. With the assistance of time-distance radio-frequency records, we robustly justified the enamel-dentin interface, dentin-pulp interface, and the cemento-enamel junction. The alveolar crest level, the location of cemento-enamel junction, and the thickness of alveolar crest were measured from the images and compared favorably with those from the cone beam computed tomography with less than 10% difference. This preliminary and fundamental study has reinforced the conclusions from previous studies, that ultrasonography has great potential to become a non-invasive diagnostic imaging tool for quantitative assessment of periodontal structures and better delivery of oral care.

Impact of selective alveolar decortication on bisphosphonate burdened alveolar bone during orthodontic tooth movement.

OBJECTIVE To investigate the effect of Selective Alveolar Decortication (SADc) facilitated orthodontic tooth movement (OTM) on bisphosphonate burdened alveolar bone in a rodent model. DESIGN OTM was accomplished by protraction of the maxillary right first molars. Four groups were included of which two groups were pre-treated for three months with alendronate sodium (BP+TM+SADc and BP+TM group) and two groups were given saline (TM+SADc and TM group). Selective alveolar decortication surgery was performed on day 1 of appliance insertion. OTM measurements were obtained at 0, 4, and 8 weeks using in-vivo μCT. Tissues were analysed by histology and EPMA. RESULTS Tooth movement of 0.39 mm and 0.75 mm in the BP+TM+SADc group at 4 and 8 weeks respectively was achieved with 113% increase in tooth movement compared to BP+TM group at 4 weeks. In comparison, SADc+TM group showed 0.63 mm and 2.1 mm of tooth movement at 4 weeks and 8 weeks respectively with only 6% increase at 4 weeks and 2% increase at 8 weeks compared to TM group. Severe interproximal and buccal bone loss around the first permanent molar in the BP+TM+SADc group was seen with μCT imaging and histology. Animals in BP+TM+SADc group histologically showed signs of osteonecrotic bone with irregular borders, loss of osteocytes and absence of osteocytic lacunae. CONCLUSION This study demonstrated selective alveolar decortication accelerates tooth movement in a bisphosphonate burdened alveolar bone in the short term but the potential of such an invasive injury can have adverse effects.

Comparison of ultrasound imaging and cone-beam computed tomography for examination of the alveolar bone level: A systematic review

Background and objective The current methods to image alveolar bone in humans include intraoral 2D radiography and cone-beam computed tomography (CBCT). However, these methods expose the subject to ionizing radiation. Therefore, ultrasound imaging has been investigated as an alternative technique, as it is both non-invasive and free from ionizing radiation. In order to assess the validity and reliability of ultrasonography in visualizing alveolar bone, a systematic review was conducted comparing ultrasound imaging to CBCT for examination of the alveolar bone level. Study design Seven databases were searched. Studies addressing examination of alveolar bone level via CBCT and ultrasound were selected. Risk of bias under Cochrane guidelines was used as a methodological quality assessment tool. Results All the four included studies were ex vivo studies that used porcine or human cadaver samples. The alveolar bone level was measured by the distance from the alveolar bone crest to certain landmarks such as cemento-enamel junction or gingival margin. The risk of bias was found as low. The mean difference between ultrasound and CBCT measurements ranged from 0.07 mm to 0.68 mm, equivalent to 1.6% - 8.8%. Conclusions There is currently preliminary evidence to support the use of ultrasonography as compared to CBCT for the examination of alveolar bone level. Further studies comparing ultrasound to gold standard methods would be necessary to help validate the accuracy of ultrasonography as a diagnostic technique in periodontal imaging.