Chung How Kau

MI Paste Plus to prevent demineralization in orthodontic patients: A prospective randomized controlled trial

INTRODUCTION Enamel demineralization is a problem in orthodontics. Fluoride is partially effective in addressing this problem, but additional treatment options are needed. The objective of this prospective randomized controlled trial was to determine the effectiveness of a new product, MI Paste Plus (GC America, Alsip, Ill), in the prevention or reduction of white spot lesions in orthodontic patients. METHODS Sixty patients who were undergoing routine orthodontic treatment were recruited for this prospective randomized clinical trial. A double-blind method of randomization was used to determine whether each patient received the MI Paste Plus or a placebo paste (Toms of Maine, Salisbury, United Kingdom). Each patient was asked to administer the paste by using a fluoride tray for a minimum of 3 to 5 minutes each day at night after brushing. Photographic records obtained in a light-controlled environment were used to record the presence or absence of white spot lesions in both groups. The enamel decalcification index was used to determine the number of white spot lesions per surface at each time interval. Patients were followed at 4-week intervals for 3 months. A scoring system from 0 to 6 was used to determine the level of caries or cavitations. This system was also used for each tooth at each time interval. RESULTS Fifty patients (26 using MI Paste Plus, 24 using the placebo paste) completed the study. The enamel decalcification index scores for all surfaces were 271 and 135 at the start of treatment and 126 and 258 at the end of treatment for the MI Paste Plus and placebo paste groups, respectively. The enamel decalcification index scores in the MI Paste Plus group reduced by 53.5%, whereas the placebo group increased by 91.1% during the study period. A 3-way analysis of variance (ANOVA) was done for the average enamel decalcification index scores. The surface type, the product/time interactions, and the product/surface interactions of the mean enamel decalcification index scores were significant (P <0.05). CONCLUSIONS MI Paste Plus helped prevent the development of new white spot lesions during orthodontic treatment and decreased the number of white spot lesions already present. The placebo paste had no preventive action on white spot development during orthodontic treatment; the number of lesions actually increased. MI Paste Plus reduced white spots on the gingival surfaces; the placebo paste had the opposite effect. The incisal surface effect on the mean enamel decalcification index scores over time and between products was highly significant. The incisal enamel decalcification index scores were consistently higher than those for the other surfaces (mesial, distal, and gingival).

Outcome Study of Computer-Aided Surgical Simulation in the Treatment of Patients with Craniomaxillofacial Deformities

PURPOSE The purpose of this study was to determine whether the surgical outcomes achieved with computer-aided surgical simulation (CASS) are better than those achieved with traditional methods. MATERIALS AND METHODS Twelve consecutive patients with craniomaxillofacial (CMF) deformities were enrolled. According to the CASS clinical protocol, a 3-dimensional computer composite skull model for each patient was generated and reoriented to the neutral head posture. These models underwent 2 virtual surgeries: 1 was based on CASS (experimental group) and the other was based on traditional methods 1 year later (control group). Once the 2 virtual surgeries were completed, 2 experienced oral and maxillofacial surgeons at 2 different settings evaluated the 2 surgical outcomes. They were blinded to the planning method used on the virtual models and each others evaluation results. The primary outcome was overall CMF skeletal harmony. The secondary outcomes were individual maxillary, mandibular, and chin harmonies. Statistical analyses were performed. RESULTS Overall CMF skeletal harmony achieved with CASS was statistically significantly better than that achieved with traditional methods. In addition, the maxillary and mandibular surgical outcomes achieved with CASS were significantly better. Furthermore, although not included in the statistical model, the chin symmetry achieved by CASS tended to be better. A regression model was established between mandibular symmetry and overall CMF skeletal harmony. CONCLUSION The surgical outcomes achieved with CASS are significantly better than those achieved with traditional planning methods. In addition, CASS enables the surgeon to better correct maxillary yaw deformity, better place proximal/distal segments, and better restore mandibular symmetry. The critical step in achieving better overall CMF skeletal harmony is to restore mandibular symmetry.

Cone-beam computed tomography of the maxillofacial region--an update.

During the last few years, craniomaxillofacial diagnosis of the head has been confronted with an increasing number of innovations and improvements. The main progress occurred following the introduction of cone‐beam technology in computed tomography in the 1990s. The number of manufacturers and devices using this technology for the maxillofacial region is growing rapidly and they are now becoming readily available.

A blind accuracy assessment of computer-modeled forensic facial reconstruction using computed tomography data from live subjects

A computer modeling system for facial reconstruction has been developed that employs a touch-based application to create anatomically accurate facial models focusing on skeletal detail. This article discusses the advantages and disadvantages of the system and illustrates its accuracy and reliability with a blind study using computed tomography (CT) data of living individuals. Three-dimensional models of the skulls of two white North American adults (one male, one female) were imported into the computer system. Facial reconstructions were produced by two practitioners following the Manchester method. Two posters were produced, each including a face pool of five surface model images and the facial reconstruction. The face pool related to the sex, age, and ethnic group of the target individual and included the surface model image of the target individual. Fifty-two volunteers were asked to choose the face from the face pool that most resembled each reconstruction. Both reconstructions received majority percentage hit rates that were at least 50% greater than any other face in the pool. The combined percentage hit rate was 50% above chance (70%). A quantitative comparison of the facial morphology between the facial reconstructions and the CT scan models of the subjects was carried out using Rapidform™ 2004 PP2-RF4. The majority of the surfaces of the facial reconstructions showed less than 2.5 mm error and 90% of the male face and 75% of the female face showed less than 5 mm error. Many of the differences between the facial reconstructions and the facial scans were probably the result of positional effects caused during the CT scanning procedure, especially on the female subject who had a fatter face than the male subject. The areas of most facial reconstruction error were at the ears and nasal tip.

Evaluation of CBCT Digital Models and Traditional Models Using the Little's Index

OBJECTIVE To determine if measurements obtained from digital models from cone beam computed tomography (CBCT) images were comparable to the traditional method of digital study models by impressions. MATERIALS AND METHODS Digital models of 30 subjects were used. InVivoDental (Anatomage, San Jose, Calif) software was used to analyze CBCT scans taken by a Galileos cone beam scanner (Sirona, Charlotte, NC) with a field of view of 15 x 15 x 15 cm(3) and a voxel resolution of 0.125 mm. OrthoCAD (Cadent, Fairview, NJ) software was used to analyze impression scans of patients at different stages of orthodontic treatment. Impressions were taken using alginate and were mailed to OrthoCAD for digital conversion. The scans were then electronically returned in digital format for analysis. RESULTS The maxillary mean scores for the Littles Index were 9.65 mm for digital models and 8.87 mm for InVivoDental models, respectively. The mandibular mean scores for the Littles Index were 6.41 mm for digital models and 6.27 mm for InVivoDental models, respectively. The mean overjet measurements were 3.32 mm for digital models and 3.52 mm for InVivoDental models, respectively. The overbite measurements were 2.29 mm for digital models and 2.26 mm for InVivoDental models, respectively. The paired t-test showed no statistical significance between the differences in all measurements. CONCLUSIONS CBCT digital models are as accurate as OrthoCAD digital models in making linear measurements for overjet, overbite, and crowding measurements.

A three-dimensional evaluation of postoperative swelling following orthognathic surgery at 6 months.

Background: Advances in three-dimensional technology have enabled applications for the clinical setting to be created and used in routine diagnosis, treatment planning, and patient education. The objectives of this prospective clinical trial were to determine the volume changes associated with facial swelling following orthognathic surgery. Methods: Twelve subjects requiring orthognathic surgery were recruited for the study. Laser scanned images of the subjects were obtained under a reproducible, controlled environment with two laser-scanning devices assembled as a stereo pair. Three-dimensional laser scans were recorded over six time periods, as follows: T1, presurgical scan; T2, 1 day postoperatively; T3, 1 week postoperatively; T4, 1 month postoperatively; T5, 3 months postoperatively; and T6, 6 months postoperatively. Results: The results showed a clinical difference in the mean shell deviations between bimaxillary and single-jaw orthognathic surgery. Furthermore, the results suggest that the mean volume of swelling was reduced by approximately 60 percent within the first month after surgery. Finally, the amounts of swelling following surgery were greater in bimaxillary cases. The recovery in the swelling was also faster in this group of patients. Conclusions: Three-dimensional imaging has opened up new avenues of patient care and treatment evaluation. The results have shown that the laser scanning device and the method described are a reliable and accurate measure of facial swelling following surgery.

Measuring adult facial morphology in three dimensions.

OBJECTIVES The aim of this study is to evaluate the reliability of measuring three-dimensional soft tissue morphology using a laser imaging system. DESIGN Prospective clinical trial. MATERIALS AND METHODS Thirty-eight adult subjects, mean age 24.5 years, were analyzed for soft tissue changes at baseline (T1) and at 1 week (T2) using two commercially available Minolta Vivid 900 (Osaka, Japan) laser scanning devices assembled as a stereopair. Left and right images were merged to form the whole face, and these images were superimposed to assess the errors between the two faces at T1 and at T2. RESULTS The results showed that the mean shell deviations for left and right scans at T1 were 0.32 +/- 0.08 mm and 0.30 +/- 0.09 mm for males and females, respectively. The mean shell deviations for left and right scans at T2 were 0.34 +/- 0.08 mm and 0.32 +/- 0.09 mm for males and females, respectively. The mean difference of the merged composite faces superimposed at T1 and T2 was 0.37 +/- 0.07 mm and 0.35 +/- 0.09 mm for males and females, respectively. Paired t-tests revealed that the mean difference of 0.02 mm was statistically insignificant (P > .05). The reproducibility error was 0.7 and 0.8 mm for females and males, respectively, when a tolerance of 90% was imposed on the aligned faces. CONCLUSIONS Capturing soft tissue morphology of the face, using the technique described, is clinically reproducible within 1 week of the initial records.

A New Method to Orient 3-Dimensional Computed Tomography Models to the Natural Head Position: A Clinical Feasibility Study

PURPOSE The purpose of this study was to evaluate the clinical feasibility of a new method to orient 3-dimensional (3D) computed tomography models to the natural head position (NHP). This method uses a small and inexpensive digital orientation device to record NHP in 3 dimensions. This device consists of a digital orientation sensor attached to the patient via a facebow and an individualized bite jig. The study was designed to answer 2 questions: 1) whether the weight of the new device can negatively influence the NHP and 2) whether the new method is as accurate as the gold standard. PATIENTS AND METHODS Fifteen patients with craniomaxillofacial deformities were included in the study. Each patients NHP is recorded 3 times. The first NHP was recorded with a laser scanning method without the presence of the digital orientation device. The second NHP was recorded with the digital orientation device. Simultaneously, the third NHP was also recorded with the laser scanning method. Each recorded NHP measurement was then transferred to the patients 3D computed tomography facial model, resulting in 3 different orientations for each patient: the orientation generated via the laser scanning method without the presence of the digital orientation sensor and facebow (orientation 1), the orientation generated by use of the laser scanning method with the presence of the digital orientation sensor and facebow (orientation 2), and the orientation generated with the digital orientation device (orientation 3). Comparisons are then made between orientations 1 and 2 and between orientations 2 and 3, respectively. Statistical analyses are performed. RESULTS The results show that in each pair, the difference (Δ) between the 2 measurements is not statistically significantly different from 0°. In addition, in the first pair, the Bland-Altman lower and upper limits of the Δ between the 2 measurements are within 1.5° in pitch and within a subdegree in roll and yaw. In the second pair, the limits of the Δ in all 3 dimensions are within 0.5°. CONCLUSION Our technique can accurately record NHP in 3 dimensions and precisely transfer it to a 3D model. In addition, the extra weight of the digital orientation sensor and facebow has minimal influence on the self-balanced NHP establishment.

Use of 3-dimensional surface acquisition to study facial morphology in 5 populations

INTRODUCTION The aim of this study was to assess the use of 3-dimensional facial averages for determining morphologic differences from various population groups. METHODS We recruited 473 subjects from 5 populations. Three-dimensional images of the subjects were obtained in a reproducible and controlled environment with a commercially available stereo-photogrammetric camera capture system. Minolta VI-900 (Konica Minolta, Tokyo, Japan) and 3dMDface (3dMD LLC, Atlanta, Ga) systems were used. Each image was obtained as a facial mesh and orientated along a triangulated axis. All faces were overlaid, one on top of the other, and a complex mathematical algorithm was performed until average composite faces of 1 man and 1 woman were achieved for each subgroup. These average facial composites were superimposed based on a previously validated superimposition method, and the facial differences were quantified. RESULTS Distinct facial differences were observed among the groups. The linear differences between surface shells ranged from 0.37 to 1.00 mm for the male groups. The linear differences ranged from 0.28 and 0.87 mm for the women. The color histograms showed that the similarities in facial shells between the subgroups by sex ranged from 26.70% to 70.39% for men and 36.09% to 79.83% for women. The average linear distance from the signed color histograms for the male subgroups ranged from -6.30 to 4.44 mm. The female subgroups ranged from -6.32 to 4.25 mm. CONCLUSIONS Average faces can be efficiently and effectively created from a sample of 3-dimensional faces. Average faces can be used to compare differences in facial morphologies for various populations and sexes. Facial morphologic differences were greatest when totally different ethnic variations were compared. Facial morphologic similarities were present in comparable groups, but there were large variations in concentrated areas of the face.

Three-dimensional evaluation of early crossbite correction: a longitudinal study

The aim of this longitudinal study was to assess whether correction of unilateral posterior crossbite in the primary dentition results in improvement of facial symmetry and increase of palatal surface area and palatal volume. A group of 60 Caucasian children in the primary dentition, aged 5.3 ± 0.7 years, were collected at baseline. The group consisted of 30 children with a unilateral posterior crossbite with midline deviation of at least 2 mm (CB) and 30 without malocclusion (NCB). The CB group was treated using an acrylic plate expander. The childrens faces and dental casts were scanned using a three-dimensional laser scanning device. Non-parametric tests were used for data analysis to assess differences over the 30 months period of follow-up. The CB children had statistically significantly greater facial asymmetry in the lower part of the face (P < 0.05) and a significantly smaller palatal volume (P < 0.05) than the NCB children at baseline. There were no statistically significant differences between the two groups at 6, 12, 18, and 30 months follow-ups. Treatment of unilateral posterior crossbite in the primary dentition period resulted in an improvement of facial symmetry in the lower part of the face (P < 0.05) and increase of the palatal surface area and palatal volume (P < 0.001). At 30 months, relapse was observed in eight children (26.7 per cent). Treatment of unilateral posterior crossbite in the primary dentition improves facial symmetry and increases the palatal surface area and the palatal volume, though it creates normal conditions for normal occlusal development and skeletal growth.