Traditional Cephalometric Analysis Research Articles

Clinical Accuracy of Bimaxillary Surgery Completed with Custom Prefabricated Splints vs. Patient-specific Surgical Guides and Plates

Abstract Purpose Virtual surgical planning (VSP) has improved outcomes in bimaxillary orthognathic surgery when compared to traditional cephalometric analysis and model surgery. However, several studies have shown discrepancies between the planned and post-operative position of the maxilla with the use of VSP and splints. Patient-specific Implants (PSIs) have the maxillary movement and final position built into them as dictated by the virtual surgical plan, completely independent of the mandibular position and have shown promising results, but are limited in number and by sample size and no study to date has directly compared the accuracy of splints versus PSIs. The purpose of our study was to determine the accuracy of splints versus PSIs in executing a virtual surgical plan. Materials and Methods A retrospective analysis of patients who underwent bimaxillary orthognathic surgery with splints or PSIs planned with VSP at our institution from 2017 to present was completed. The difference in maxillary positions from the VSP to the post-operative CBCT were evaluated in both cohorts. The primary predictor variable was the planned 3D position of the maxillary mid-incisors, and right and left first molars in the antero-posterior, transverse, and vertical dimensions. The primary outcome variable was the post-operative 3D position of these points. The root mean square deviation (RMSD) was used to calculate the absolute value of the mean differences. A paired t test was used to determine if there were statistically significant differences between the predicted and observed positions with p < 0.05 Results A total of 65 patients (46 female, 19 male) aged 14 to 58 years (mean age, 23.3 years). 10 patients (8 female, 2 male) aged 14 to 54 years (mean age, 24.8 years) underwent bimaxillary surgery with a Le Fort 1 osteotomy and a mandibular sagittal split osteotomy or intraoral vertical ramus osteotomy and were rigidly fixated after the use of a splint to facilitate the final maxillary position, whereas 55 patients (38 female, 17 male) aged 14 to 58 years (mean age, 22.7 years) were rigidly fixated with the use of a PSI. The difference between the planned and actual movements varied in all dimensions in the splint cohort but was greatest in the anteroposterior dimension for all points in the PSI cohort. The only statistically significant differences in pre-operative and post-operative position of the splint group were the mid-incisor transverse and vertical dimensions, whereas all differences in the PSI cohort were found to be statistically significant with the exception of the maxillary right 1st molar in the transverse dimension and the maxillary left 1st molar in the vertical dimension. There was an overall tendency for undertreatment in all directions as shown in the deviation from 0 toward under (-) or over (+) correction, regardless of type of surgery performed. Also, there was no indication that posterior or anterior movements were more or less accurate in either group. The PSI group was more accurate at all 3 maxillary points in all 3 dimensions, ranging from 1% to 62.8% more accurate than the splint group. Conclusion The use of a PSI allows for greater control of the post-operative position of the maxilla when planned via VSP and is more accurate than the use of a splint.

How accurate are patient-specific osteotomy guides and fixation plates in orthognathic surgery?

PurposeThis study evaluates the accuracy of orthognathic surgical movements completed with patient-specific osteotomy guides and fixation plates and provides an example of the use of volumetric analysis to evaluate post-surgical results. Materials and methodsUtilizing three-dimensional (3D) overlay and anthropometric points, the pre-operative virtual surgical plan (VSP) was compared to the post-operative computed tomography (CT) scan. The average deviation in the movements between each patient's scans was calculated; additionally, volumetric analysis consisted of overlapping the virtually planned jaws with the surgically obtained maxilla and mandible, allowing accuracy to be calculated as a percentage and provide visualization of where errors occurred. Results9 orthognathic surgeries were completed using patient-specific guides and plates. In the anterior-posterior and left-right planes, the maxilla was under-corrected 0.79 mm and 0.01 mm respectively, whereas it was over-corrected in the superior-inferior plane by 0.15 mm; this corresponded with an average maxillary volume overlap of 82.59%. In the left-right and superior-inferior planes, the mandible was under-corrected 1.40 mm and 0.36 mm respectively, whereas it was over-corrected in the left-right plane by 0.10 mm; this corresponded with an average mandibular volume overlap of 77.52%. The volume overlap difference between the maxilla and mandible was not significant. ConclusionPatient-specific guides and plates in orthognathic surgery can achieve acceptable results when measured by traditional cephalometric point analysis. Our protocol demonstrates the use of pre- and post-surgical CT scans to compare and evaluate surgical outcome as a percentage of positional volumetric accuracy as well as pinpoint the sources of error.

0882 Local Deformation Analysis of Lateral Cephalogram for Childhood OSA Classification

Abstract Introduction Craniofacial profile is one of the anatomical causes of obstructive sleep apnea (OSA). Cephalometry provides information on patients’ skeletal structures and soft tissues. Traditional cephalometric analysis focuses on linear distances, angles, ratios and area of specific variables. Its classification power is often disappointed. In this study, a novel approach to cephalometric analysis using local deformation information was carried out to assess its efficacy in OSA classification. Methods This study was a retrospective analysis based on 60 case-control pairs who were Chinese children recruited for sleep studies in the Prince of Wales Hospital, with accessible lateral cephalometry and polysomnography (PSG) data. Local deformation technique was adopted to derive 1215 deformations from 15 manual landmarking on each cephalogram. In addition, three linear distances (hyoid bone to mandibular plane, hyoid bone to posterior pharyngeal wall, and minimal distance between tongue base and posterior pharyngeal wall) were measured from each cephalogram. A total of 1218 information features were obtained per subject. Classification models were built with an equal ratio between OSA and non-OSA groups (defined by OAHI≥1 and OAHI&amp;lt;1 respectively). Forty pairs were used as training data and twenty pairs were used as testing data. Results Three model settings which used all 1218 cephalometric features, 800 features, and 500 features were tested. The accuracy for the three settings were 67.5% (sensitivity: 70%, specificity: 65%), 87.5% (sensitivity: 90%, specificity: 85%), and 92.5% (sensitivity: 95%, specificity: 90%) respectively. Apart from the three distances, the 500 topmost discriminative features were predominantly landmarks around the nasal cavity. Conclusion A new approach to cephalometric analysis using local deformation information can provide additional details on each cephalogram, hence, achieving better classification. The classification models using 500 features yielded the highest accuracy among the three settings. This setting could benefit most from the comprehensive comparison while avoiding overfitting. Support -

Midface correction in patients with Crouzon syndrome is Le Fort III distraction osteogenesis with a rigid external distraction device the gold standard?

IntroductionLe Fort III distraction osteogenesis with a rigid external distraction device is a powerful procedure to correct both exorbitism and impaired airways in faciocraniosynostosis. The aim of this study was to investigate treatment effect, perioperative parameters and volumetric outcomes after Le Fort III distraction osteogenesis in patients with Crouzon syndrome in a retrospective study design and to explore potential strengths and weaknesses of this procedure. Materials and methodsFrom June 2013 to February 2015, a total of nine children with Crouzon syndrome underwent Le Fort III distraction osteogenesis with a rigid external distraction device (RED device, KLS Martin, Tuttlingen, Germany). Along with perioperative parameters, sleep study reports, traditional cephalometric analysis, three-dimensional imaging and photographs were evaluated for severity of disease and therapeutic effect and structural and functional changes of the upper airway preoperatively, after device removal and one year postoperatively. ResultsSurgery for Le Fort III distraction was performed at a median age of 12.5 years (SD 2.5 months) with an average weight of 43.0 kg (SD 12.9 kg). Mean estimated blood loss was 535.7 ml (SD 128.1 ml), not requiring any red blood cell transfusions. Mean duration of surgery was 240 min (SD 30.6min), average hospital stay eight days (SD 0.5 days) with a planned median ICU stay of 1.7 days (SD 0.4 days) for all patients.There were a total of five minor complications. Exorbitism and Angle class III malocclusions were corrected in all patients. No patient showed velopharyngeal problems postoperatively. The average amount of distraction was 18.4 mm (14–26 mm). Average length of the distraction period was 18.3 days (SD 0.4 days), with a total distraction plus consolidation time of three months (SD 0.25 months). In two patients, vector correction was performed during distraction. A counterclockwise movement despite vector correction, clinically resulting in an open bite, was observed in one of these two patients. Eight of the nine patients showed a frontal overbite at the end of the distraction period.Cephalometric analysis revealed a significant increase of Sella-Nasion-Point A angle (SNA) from 76.0° (+/− 2.9; T1) to 86.0° (+/− 3.4; T2) (p = 0.006) and growth-related point A-Nasion-point B angle (ANB) from −4.8° (+/−3.7) to 5.7° (+/−4.8) (p = 0.001) from preoperatively to device removal and stable results one year postoperatively.Upper airway structure and respiratory function were improved clinically after the Le Fort III DO treatment in all cases with an average posterior airway space increase from 3199 mm3 (+/− 229.6 mm3) to 8917,7 ml (+/−415.1 mm3) (T1 to T2).Surgical outcome was judged good to excellent both by patients and families and the craniofacial team. ConclusionLe Fort III DO with a rigid external distraction device in patients with Crouzon syndrome is a powerful and reliable surgical procedure that reliably produces a more significant change of appearance than most other single procedures routinely performed by craniofacial surgeons. It effectively treated sleep apnea in the affected patients. In our collective, the maxilla remained stable after advancement without any relapse, but there was no subsequent anterior growth on one year follow-up. Careful vector planning was able to avoid frontal open bite in eight patients. Complication rates were acceptably low and patients’ functional and esthetic outcome was high.

The relationship between 3D dentofacial photogrammetry measurements and traditional cephalometric measurements

Objectives:. To determine the relationship between traditional cephalometric measurements and corresponding nonradiographic three-dimensional (3D) photogrammetry measurements.Materials and Methods:. This was a cross-sectional study of 20 orthodontic patients (10 male and 10 female) who received lateral cephalometric radiographs and 3D dentofacial photogrammetric records with each subject serving as his or her own control for a total sample size of 40 images (20 per method). A 3D analysis that resembled a traditional cephalometric analysis was established using the eyes and natural head orientation as substitutes for the cranial base. Pearson correlation coefficients and multivariable linear regression plots were calculated to evaluate the relationship between the photogrammetry measurements and the cephalometric measurements.Results:. The ANB angle, mandibular plane angle, lower anterior face height, upper incisor angle to SN, upper incisor angle to NA, and all measurements of lower incisor position and inclination had strong positive Pearson correlation coefficients with the corresponding 3D photogrammetry measurements (P < .004). Statistically significant regression plots demonstrated that cephalometric relationships between the jaws and incisor orientation can be predicted from corresponding 3D photogrammetry measurements.Conclusions:. 3D photogrammetry measurements relating the jaws to each other and incisor orientation has a strong positive correlation with corresponding traditional cephalometric measurements and can serve as cephalometric predictors. Capturing the eyes using 3D photogrammetry can obviate the need to expose the cranial base and allow limiting the radiographic field to the area of interest.

The relationship between 3D dentofacial photogrammetry measurements and traditional cephalometric measurements.

To determine the relationship between traditional cephalometric measurements and corresponding nonradiographic three-dimensional (3D) photogrammetry measurements. This was a cross-sectional study of 20 orthodontic patients (10 male and 10 female) who received lateral cephalometric radiographs and 3D dentofacial photogrammetric records with each subject serving as his or her own control for a total sample size of 40 images (20 per method). A 3D analysis that resembled a traditional cephalometric analysis was established using the eyes and natural head orientation as substitutes for the cranial base. Pearson correlation coefficients and multivariable linear regression plots were calculated to evaluate the relationship between the photogrammetry measurements and the cephalometric measurements. The ANB angle, mandibular plane angle, lower anterior face height, upper incisor angle to SN, upper incisor angle to NA, and all measurements of lower incisor position and inclination had strong positive Pearson correlation coefficients with the corresponding 3D photogrammetry measurements ( P < .004). Statistically significant regression plots demonstrated that cephalometric relationships between the jaws and incisor orientation can be predicted from corresponding 3D photogrammetry measurements. 3D photogrammetry measurements relating the jaws to each other and incisor orientation has a strong positive correlation with corresponding traditional cephalometric measurements and can serve as cephalometric predictors. Capturing the eyes using 3D photogrammetry can obviate the need to expose the cranial base and allow limiting the radiographic field to the area of interest.

Abstract: CT Analysis of Micrognathia: Do Cephalometrics Predict Management Course?

INTRODUCTION: Mandibular micrognathia is the primary defining characteristic of Pierre Robin Sequence (PRS) that sets off a physiologic cascade with varying severity of airway obstruction.1 The diagnosis of micrognathia is predominantly clinical, though with the advent of three-dimensional computed tomography (3D-CT), the development of objective and accurate measurements of skeletal morphology could be a useful clinical adjunct for management.2 The aim of this study is to investigate the efficacy of using cephalometric analysis to guide clinical management: non-operative treatment, mandibular distraction, tracheostomy. METHODS: Records were retrospectively reviewed from 2004–2016 (IRB#2011-0247). Infants less than one year of age with PRS, evaluated for surgical management of micrognathia with a CT scan were included. 3D-CT analysis of total mandibular length (Co-Gn) and total midface length (Co-A) was performed in addition to traditional cephalometric analysis – Co-Gn, Co-A, SNA, SNB, ANB – in reformatted sagittal CT scans. Clinical data collected included age at CT scan, sex, and associated syndromic status. Chi-squared and Kruskal-Wallis tests were used to compare values among patients that were managed non-operatively, with mandibular distraction osteogenesis (MDO), and tracheostomy at any point, with Mann-Whitney U test reserved for comparing two groups. RESULTS: 147 patients met inclusion; 33 non-operative, 73 MDO, 41 tracheostomy. CT scans were performed at an older age in the tracheostomy group compared to the non-operative and MDO groups (96.3, 58.3, 39.4 days, respectively; p=0.02). Likewise, the tracheostomy group had a greater proportion of syndromic patients compared to non-operative and MDO groups (76%, 36%, 40%, respectively; p=0.0003). Traditional cephalometric measures demonstrated no differences among the groups: Co-Gn (non-operative: 43.0mm, MDO: 41.2mm, tracheostomy: 41.1mm; p=0.17), Co-A (41.7, 40.7, 41.5mm, respectively; p=0.28), ANB (18.1°, 19.2°, 20.3°, respectively; p=0.37), SNA (84.3°, 83.0°, 84.0°, respectively; p=0.46), and SNB (66.1°, 63.8°, 63.6°, respectively; p=0.14). 3D-CT analysis of total mandibular length (46.3, 46.2, 45.2mm, respectively; p=0.48) and total midface length (49.3, 48.5, 48.5mm, respectively; p=0.37) did not differ among groups. CONCLUSION: Cephalometric measurements from computed tomographic scans did not differ among patients that were managed non-operatively, underwent mandibular distraction, or tracheostomy. These results illustrate the limitation of solely using skeletal data as a means to predict the need for surgical intervention for airway compromise. Reference Citations: 1. Pruzansky S, Richmond JB. Growth of Mandible in Infants with Micrognathia Clinical Implications. Archives of Pediatrics & Adolescent Medicine. 1954;88(1):29. doi:10.1001/archpedi.1954.02050100031005. 2. Breugem CC, Evans KN, Poets CF, et al. Best Practices for the Diagnosis and Evaluation of Infants With Robin Sequence. JAMA Pediatrics. 2016;170(9):894. doi:10.1001/jamapediatrics.2016.0796.

An evaluation of the reproducibility of landmark identification in traditional versus computer-assisted digital cephalometric analysis system

Objective To determine the reliability of Computer Assisted Digital Cephalometric Analysis System (CADCAS) in terms of landmark identification on the values of cephalometric measurements in comparison with those obtained from original radiographs. Materials and Methods The study material consisted of Twenty five lateral cephalograms selected randomly, 16 cephalometric points together with 10 angular and 5 linear cephalometric measurements. The landmarks were manually picked on the tracing &amp; the measurements of X &amp;Y axis done with reference grid. The same tracing was digitized &amp; image loaded in the software (ViewBox 3.1.1) was checked for the magnification (metal ruler) &amp; distortion. The second part of the study compared manual and the CADCAS since the landmarks were manually digitized on screen as against the manually picked ones on the tracing paper. The x and y-coordinates for 16 landmarks were measured, mean and standard deviation calculated, linear and angular measurements compared. Statistical Analysis A paired t-test was done to calculate the statistical significance of the differences. Intraclass reliability coefficient (signifying reproducibility) of the variable was recorded. The observations were tabulated and analysis was done using the paired t test at a P value &lt;0.05. Results Out of 47 variables looked for, 21 showed statistical significance. Direct digitization onscreen (CADCAS) was the quickest and least tedious method. CADCAS was unreliable with linear measurements involving bilateral structures such as Gonion &amp; Articulare. Conclusions Both the methods are equally reliable and reproducible. The intra-class reliability coefficient of all variables differed only slightly, which is not clinically significant.

Repeatability of three-dimensional measurements based on cone-beam CT images

To investigate the repeatability of three-dimensional (3-D) cephalometric measurements for the clinical application of 3-D cephalometry. Forty-nine measurements that widely used in traditional cephalometric analyses were defined in 3-D cone-beam CT (CBCT) images. Three examiners identified landmarks on CBCT images of 17 subjects with normal occlusion, respectively, and 3-D measurements were exported automatically by software SimPlant. Inter-examiner reliability correlation coefficients (ICC) were obtained for all measurements. Repeatability of 36 measurements was high (ICC value greater than 0.9), including SNA, SNB. Repeatability of 11 measurements was moderate (ICC value between 0.8 and 0.9), including CoL-GoL, CoL-MSP. Repeatability of 2 measurements was low (ICC value lower than 0.8), including Gn-MSP and MPR-MSP. Most 3-D cephalometric measurements based on CBCT had high repeatability. However, some 3-D cephalometric measurements had limited repeatability.

Outcomes in Computer-Assisted Surgical Simulation for Orthognathic Surgery

Orthognathic surgery is a powerful tool to address skeletal discrepancies of the jaws; however, the model surgery and splint fabrication necessary to successfully complete this surgery are laborious and time consuming. Previous studies have described the utility of computer-assisted surgical simulation (CASS) to eliminate the need for plaster cast model surgery. This article evaluates the implementation of a CASS system for treatment planning and splint fabrication in a series of 11 orthognathic surgery patients. All patients were treatment planned using a CASS system for computer-simulated osteotomies and splint fabrication. As a safety measure, traditional model surgery and splint fabrication were also performed on all cases. Each case was evaluated for accuracy of cephalometric analysis, splint accuracy, splint durability, and ease of treatment planning. All splints fit as well, or better, than those fabricated using traditional methods. In 2 cases, occlusal cants were detected by the CASS system that were undetected by traditional cephalometric analysis and physical examination. In 1 case, the skeletal midline identified on the computed tomographic scan was incongruent with the soft tissue clinical midline of the face, and this discrepancy was recognized and compensated for by correlation of the physical examination and preoperative clinical photos.In this series of 11 patients, the CASS system proved to be an effective mechanism to treatment plan cases and prepare surgical splints for patients undergoing orthognathic surgery.

Analyse comparative des valeurs céphalométriques de céphalogrammes latéraux générés par CBCT versus céphalogrammes latéraux conventionnels

This study compared angular cephalometric values from scanned traditional lateral cephalograms versus CBCT generated slices. Traditional lateral cephalograms (using Orthoceph OC100) and volumetric CBCT imaging (using NewTom 3G Volume Scanner) were taken from 36 patients. Lateral cephalometric analysis using Dolphin 3D was performed on the respective imported radiographic data and ten angular measurements were evaluated. The reliability of measurements was evaluated with an intra-class correlation coefficient (ICC). Paired MANOVA was used to compare differences in measurements between the two image modalities. Inter-rater reliability demonstrated high reliability in 90% of the measurements (ICC >0.8). A high intra-rater reproducibility (ICC >0.8) was demonstrated in all angles. No significant difference in the angular measurements was detected between the two image modalities (paired MANOVA p >0.1, α =0.05). A lateral slice from CBCT imaging can be used to perform traditional cephalometric analysis with levels of precision and accuracy comparable to traditional lateral cephalometrics.

O.006 Hair transplantation – a method for camouflage of scalp scars

Le Fort III distraction osteogenesis with a rigid external distraction device is a powerful procedure to correct both exorbitism and impaired airways in faciocraniosynostosis. The aim of this study was to investigate treatment effect, perioperative parameters and volumetric outcomes after Le Fort III distraction osteogenesis in patients with Crouzon syndrome in a retrospective study design and to explore potential strengths and weaknesses of this procedure.From June 2013 to February 2015, a total of nine children with Crouzon syndrome underwent Le Fort III distraction osteogenesis with a rigid external distraction device (RED device, KLS Martin, Tuttlingen, Germany). Along with perioperative parameters, sleep study reports, traditional cephalometric analysis, three-dimensional imaging and photographs were evaluated for severity of disease and therapeutic effect and structural and functional changes of the upper airway preoperatively, after device removal and one year postoperatively.Surgery for Le Fort III distraction was performed at a median age of 12.5 years (SD 2.5 months) with an average weight of 43.0 kg (SD 12.9 kg). Mean estimated blood loss was 535.7 ml (SD 128.1 ml), not requiring any red blood cell transfusions. Mean duration of surgery was 240 min (SD 30.6min), average hospital stay eight days (SD 0.5 days) with a planned median ICU stay of 1.7 days (SD 0.4 days) for all patients.There were a total of five minor complications. Exorbitism and Angle class III malocclusions were corrected in all patients. No patient showed velopharyngeal problems postoperatively. The average amount of distraction was 18.4 mm (14–26 mm). Average length of the distraction period was 18.3 days (SD 0.4 days), with a total distraction plus consolidation time of three months (SD 0.25 months). In two patients, vector correction was performed during distraction. A counterclockwise movement despite vector correction, clinically resulting in an open bite, was observed in one of these two patients. Eight of the nine patients showed a frontal overbite at the end of the distraction period.Cephalometric analysis revealed a significant increase of Sella-Nasion-Point A angle (SNA) from 76.0° (+/− 2.9; T1) to 86.0° (+/− 3.4; T2) (p = 0.006) and growth-related point A-Nasion-point B angle (ANB) from −4.8° (+/−3.7) to 5.7° (+/−4.8) (p = 0.001) from preoperatively to device removal and stable results one year postoperatively.Upper airway structure and respiratory function were improved clinically after the Le Fort III DO treatment in all cases with an average posterior airway space increase from 3199 mm3 (+/− 229.6 mm3) to 8917,7 ml (+/−415.1 mm3) (T1 to T2).Surgical outcome was judged good to excellent both by patients and families and the craniofacial team.Le Fort III DO with a rigid external distraction device in patients with Crouzon syndrome is a powerful and reliable surgical procedure that reliably produces a more significant change of appearance than most other single procedures routinely performed by craniofacial surgeons. It effectively treated sleep apnea in the affected patients. In our collective, the maxilla remained stable after advancement without any relapse, but there was no subsequent anterior growth on one year follow-up. Careful vector planning was able to avoid frontal open bite in eight patients. Complication rates were acceptably low and patients’ functional and esthetic outcome was high.

Lower second molar extraction in correction of severe skeletal class III malocclusion.

The purpose of this study was to evaluate dentoskeletal and soft-tissue profile changes after extraction of lower second molars and treatment using the Tip-Edge technique in severe Class III subjects. Thirteen patients with severe skeletal Class III malocclusion (four males, nine females), diagnosed as requiring orthognathic surgery, but who rejected surgical therapy, were included in the study. The average age was 13.2 +/- 0.8 years. Lateral cephalometric films taken at the beginning and the end of treatment were analyzed using the Pancherz analysis and a traditional cephalometric analysis. The arithmetic mean and standard deviation were calculated for each variable. Paired t-test was performed to evaluate significant treatment change. After active treatment, dramatic overjet change was noted, with an average value of 5.5 mm (P < .001). Inclination of lower incisors was decreased 12.0 degrees when measured to the mandibular plane (P < .001). Inclination of upper incisors was increased by 2.1 degrees to the SN plane (P > .05). A negative value of the distance between upper and lower lip position to Sn-Pg' at the beginning of treatment changed to a positive value (P < .001). The results of this preliminary study suggest that success in the treatment of some severe Class III deformity in the permanent dentition can be achieved with fixed appliances and extraction of lower second molars. A remarkable soft-tissue change was noted after the treatment, and concave facial profiles changed to straight profiles.

Preliminary study of non-surgical treatment of severe Class III malocclusion in 18 patients of 12-20 years old

To analyze effects of non-surgical treatment on subjects of 12-20 years old with severe skeletal Class III deformity and to directly evaluate dental and facial profile changes. Eighteen patients with severe skeletal Class III malocclusion (male 5, female 13), diagnosed as indication for orthognathic surgery, were included in the study. The average age was 14.6 +/- 2.5 years old., with age range from 12 years old to 20 years old. 12 cases were treated with Tip-Edge straight-wire technique and 6 cases with Begg light wire technique. The average treatment time was 2.5 +/- 0.8 years. The selection criteria included: (1) mesial or superior mesial Class III molar relationship, with maxillary first molar occlude the buccal groove of the mandibular second molars (2) no mandibular shift (3) ANB < -1.5 degrees (4) high angle cases with average value of SN-MP 34.9 degrees +/- 5.9 degrees, 4 cases present with openbite (5) concave facial profile (6) originally classified as surgery cases. Lateral cephalometric films taken at the beginning and the end of the treatment were analyzed with traditional cephalometric analysis. The arithmetic mean (Mean) and standard deviation (SD) were calculated for each variable. Paired t-test was performed to evaluate the significant treatment change. Normal overjet and overbite were established with proclination of upper incisors and retroclination of lower incisors. Inclination of upper incisors was increased 5.9 degrees when measured with the angle of upper incisor to SN plane (P < 0.01). Inclination of lower incisors was decreased 6.6 degrees when measured with the angle of lower incisor to mandibular plane (P < 0.001). Negative value of the distance difference of upper lip and lower lip to Sn-Pg' at the beginning of treatment changed to positive value with significant difference (P < 0.001). Successful treatment effects could be obtained with non-surgical therapy in severe skeletal Class III malocclusion in permanent dentition. Remarkable soft-tissue change was noted after the treatment and concave facial profile changed to straight profile.

Preliminary investigation of nonsurgical treatment of severe skeletal Class III malocclusion in the permanent dentition.

The purpose of the study was to analyze the effects of nonsurgical treatment on subjects with a severe skeletal Class III deformity and to directly evaluate dental and facial profile changes. Eighteen patients with severe skeletal Class III malocclusions (5 males, 13 females), diagnosed as indication for orthognathic surgery, were included in the study. The average age was 13.7 +/- 2.5 years. All the cases were treated with Tip-Edge straight-wire technique or Begg light wire technique. Lateral cephalometric films taken at the beginning and at the end of treatment were analyzed with the Pancherz analysis and traditional cephalometric analysis. The arithmetic mean and standard deviation were calculated for each variable and paired t-test was performed. A mean reduction of 6.5 mm in the overjet was noted (P < .001), with skeletal changes and dental changes contributing 20% and 80% to the overjet correction, respectively. The inclination of the upper incisors to the SN plane was increased 5.9 degrees (P < .01). The inclination of the lower incisors to the mandibular plane was decreased 6.6 degrees (P < .001). The difference between the distance of the upper lip and lower lip to Sn-Pg' at the beginning of treatment changed from a negative value to a positive value with a significant difference (P < .001). Successful treatment effects can be obtained with nonsurgical therapy in severe skeletal Class III malocclusions in the permanent dentition. A remarkable soft tissue change was noted after the treatment, and the concave facial profile changed to a straight profile (see two case reports).

A Retrospective Cephalometric Study of Class I Patients

In view of the growing consensus that traditional cephalometric analyses yield data of dubious scientific validity, this study was undertaken using an alternative technique, termed finite element analysis (FEA). The study was based on 14 triangular finite elements spanning seven datum (nodal) points delineating cephalometric form. These points were delineated on lateral cephalographs taken immediately before and following the completion of orthodontic treatment for two samples of boys aged 12-16 years. Although both samples exhibited Class I molar occlusions with anterior over-crowding, one sample required bilateral maxillary and mandibular first premolar extraction prior to orthodontic treatment, while the other sample did not. FEA revealed greater cephalometric size and shape changes in the 'non-extraction' than 'extraction' samples. Such sample contrasts, however, varied depending upon the finite element included in the analysis. Further studies are therefore required to delineate the specific finite element configurations to provide precise descriptions of cephalometric change.

The proportionate template as a diagnostic aid

Many traditional cephalometric analyses used do not consistently reflect the extent of anteroposterior or vertical jaw dysplasias. Nor do such analyses give accurate information as to which jaw(s) is at fault. The proportionate template is designed as a diagnostic aid which enables the clinician to identify and determine rapidly the extent of craniofacial skeletal jaw discrepancies in adults. The template is found to be particularly useful for orthodontists and surgeons engaged in orthognathic surgery. (Proportionate templates are available upon request from the author.)