Iatrogenic retroposition of the lips sequel after bicuspid extraction-a retrospective study.

AIM: This study aims to explore the prevalence of Iatrogenic retroposition of the lips sequel (IRLS) after bicuspid extraction, associated dentofacial characteristics and the effectiveness of surgical treatment. MATERIAL: and methods: Patients with bicuspid extraction as part of an orthodontic treatment plan were retrospectively included. IRLS was identified by clinical evaluation and cephalometric Legan and Burstone analysis. Association of demographic and cephalometric variables were assessed. The effectiveness of combined orthodontic-orthognathic correction of the retroposition of the lips was evaluated. RESULTS: Out of 144 patients with extracted bicuspids, eight Class I patients, nine Class II patients and five Class III patients were seeking treatment because their lips had retruded as a consequence of compensating orthodontic treatment. Lower jaw bicuspid extraction and a decreased vertical facial height in Class II patients correlated significantly more with IRLS development. Postoperative cephalometric analysis of orthodontic-orthognathic treated patients reported improvement in lip projection and naso-labial angle. Only two Class I patients reported postoperative normalization of the lip position according to Legan and Burstone. CONCLUSION: The consequence of bicuspid extractions on soft tissue profile differs according to skeletal jaw relation. The impact of orthognathic surgery on IRLS is beneficial, although insufficient to completely correct the facial profile when judged on cephalometric standards.

Automatic 3D dense phenotyping provides reliable and accurate shape quantification of the human mandible.

Automatic craniomaxillofacial (CMF) three dimensional (3D) dense phenotyping promises quantification of the complete CMF shape compared to the limiting use of sparse landmarks in classical phenotyping. This study assesses the accuracy and reliability of this new approach on the human mandible. Classic and automatic phenotyping techniques were applied on 30 unaltered and 20 operated human mandibles. Seven observers indicated 26 anatomical landmarks on each mandible three times. All mandibles were subjected to three rounds of automatic phenotyping using Meshmonk. The toolbox performed non-rigid surface registration of a template mandibular mesh consisting of 17,415 quasi landmarks on each target mandible and the quasi landmarks corresponding to the 26 anatomical locations of interest were identified. Repeated-measures reliability was assessed using root mean square (RMS) distances of repeated landmark indications to their centroid. Automatic phenotyping showed very low RMS distances confirming excellent repeated-measures reliability. The average Euclidean distance between manual and corresponding automatic landmarks was 1.40 mm for the unaltered and 1.76 mm for the operated sample. Centroid sizes from the automatic and manual shape configurations were highly similar with intraclass correlation coefficients (ICC) of > 0.99. Reproducibility coefficients for centroid size were < 2 mm, accounting for < 1% of the total variability of the centroid size of the mandibles in this sample. ICC's for the multivariate set of 325 interlandmark distances were all > 0.90 indicating again high similarity between shapes quantified by classic or automatic phenotyping. Combined, these findings established high accuracy and repeated-measures reliability of the automatic approach. 3D dense CMF phenotyping of the human mandible using the Meshmonk toolbox introduces a novel improvement in quantifying CMF shape.

Evaluation of long-term hard tissue relapse following surgical-orthodontic treatment in skeletal class II patients: A systematic review and meta-analysis.

This systematic review and meta-analysis was performed to evaluate the long-term hard tissue stability and relapse factors following surgical-orthodontic treatment in skeletal class II patients. A literature search was conducted using Embase, Cochrane Central, Web of Science, and PubMed, yielding 3184 articles published up to January 2019. Risk of bias was assessed following the Cochrane handbook. Ten articles met the inclusion criteria. A total of 1079 patients were followed up for 5-13 years. The qualitative findings showed a variety of extrinsic and intrinsic factors affecting long-term stability. Meta-analysis for the amount and direction of cephalometric landmark displacement in the vertical and sagittal planes showed significant angular increases of ANB and backward relapse of SNB, however within the clinically acceptable range of 4°. In relation to linear measurements, the mean differences in all landmarks were within the clinically acceptable range of 2mm except for gonion. In conclusion, this systematic review showed multiple intrinsic and extrinsic factors responsible for relapse. However, the outcomes of the meta-analysis are limited due to the heterogeneity of data, small number of studies, and inconsistent methods of evaluation. Further high-quality studies utilising standardised three-dimensional methodologies are required to improve the level of evidence.

Evaluation of long-term hard tissue remodelling after skeletal class III orthognathic surgery: a systematic review.

This systematic review was performed to investigate the long-term hard tissue stability in orthognathic surgery patients with skeletal class III malocclusion. A literature search was conducted using the Embase, Cochrane Central, Web of Science, and PubMed databases, yielding 3690 articles published up to June 2018. Nine articles met the inclusion criteria; these reported skeletal changes in 886 patients with between 5 and 12.7 years of follow-up. Risk of bias was assessed according to the Cochrane Handbook. Results showed variations in stability based on age, facial pattern, surgical procedure, and fixation type. Young patients showed a greater increase in mandibular length and higher A-point stability after bimaxillary surgery than older patients. Dolichofacial patients showed skeletal relapse with a facial clockwise rotation, whereas counterclockwise rotation was observed in brachyfacial patients. Single mandibular setback surgery was linked to stability loss with decreased mandibular ramus and gonion angle; meanwhile, genioplasty fell into the highly stable surgery category. The hyoid bone relapsed significantly postero-inferiorly, which correlated with suprahyoid muscle changes but little to no mandibular position changes. Fixation with monocortical miniplates showed higher patient satisfaction and better stability compared to bicortical screw fixation. These conclusions should be regarded with caution because of the lack of current evidence from three-dimensional imaging.

How accurate is digital-assisted Le Fort I maxillary osteotomy? A three-dimensional perspective.

The aim of this study was to evaluate the surgical accuracy of Le Fort I surgery compared to the three-dimensional (3D) virtual planning. Fifty-five patients (29 males, 26 females; age range 15-58 years) with skeletal class III malocclusion, who underwent bimaxillary surgery were included. A validated 3D accuracy assessment tool was utilized to assess the surgical accuracy of the maxillary positioning. For translational movements, the least amount of error was associated with mediolateral translation, whereas the surgical accuracy for anteroposterior and superoinferior translation showed a tendency towards a more posterior and inferior positioning of the maxilla compared to the planning. For rotational movements, the highest discrepancy was observed for pitch. Linear regression showed increased inaccuracy with increasing advancement for anteroposterior, superoinferior and pitch movements. To conclude, 3D virtual planning of maxilla was generally accurate when compared to achieved outcome for skeletal class III patients undergoing bimaxillary surgery.