Facial asymmetry correction: From conventional orthognathic treatment to surgery-first approach

What Features on Routine Panoramic Radiographs Could Help Orthodontists to Estimate the Occurrence of Condylar Hyperplasia from Other Mandibular Asymmetries—Retrospective Analysis Study

Hemimandibular hyperplasia (HH) and elongation (HE) are the most common pathologies present in the mandible. Presented condylar hyperplasias have their own radiological and clinical features. In most cases, patients suffer from various forms of malocclusion. From a total of 150 asymmetrical jaw radiographs evaluated, 46 were evaluated and included in this study. A retrospective study on the data of 46 selected patients treated, diagnosed, and consulted from various forms of mandibular and skeletal asymmetry based on routine diagnostic panoramic radiographs evaluated typical and atypical radiological and anatomical symptoms of condylar hyperplasia. The presented evaluation focused on mandibular, maxillary, and other bones, in order to distinguish condylar hyperplasia from other forms of mandibular asymmetry. The degree of maxillary downward growth followed by the occurrence of an open bite on the affected side estimate the degree/presence or cessation of growth in the affected condyle. Mandibular asymmetry with incisor teeth inclination remains the most typical characteristic of condylar hyperplasia. Increased height of mandibular ramus differentiates between condylar hyperplasia and elongation, which also influences the position of the inferior alveolar nerve. Mentioned symptoms, described as the acronym “Go Moira!”, are useful in a quick and simple “glimpse of an eye” differential diagnostic approach. It is possible to quickly and accurately establish the first diagnosis simply by a careful evaluation of patients’ panoramic radiographs.

Skeletal stability after bimaxillary surgery with surgery-first approach for class III asymmetry is not related to virtual surgical occlusal contact

OBJECTIVES

Surgery-first orthognathic surgery is rarely used in class III asymmetry due to concerns of reduced skeletal stability from unstable surgical occlusion. This study aimed to evaluate if skeletal stability after surgery-first orthognathic surgery is related to virtual surgical occlusal contact or surgical change.

MATERIALS AND METHODS

We studied 58 adults with class III asymmetry, consecutively corrected by Le Fort I osteotomy and bilateral sagittal split osteotomy using a surgery-first approach. Dental casts were manually set to measure virtual surgical occlusal contact including contact distribution, contact number, and contact area. Cone-beam computed tomography taken before treatment, 1-week post-surgery, and after treatment was used to measure surgical change and post-surgical stability of the maxilla and mandible in translation (left/right, posterior/anterior, superior/inferior) and rotation (pitch, roll, yaw). The relationship between skeletal stability and surgical occlusal contact or surgical change was evaluated with correlation analysis.

RESULTS

Significant instability was found in the mandible but not in the maxilla. No correlation was found between the maxillary or mandibular stability and surgical occlusal contact (all p > 0.01). However, a significant correlation was found between the maxillary (roll and yaw) or mandibular (shift, roll and pitch) stability and its surgical change (all p < 0.001).

CONCLUSIONS

In correction of class III asymmetry with surgery-first bimaxillary surgery, the skeletal stability is not related to the virtual surgical occlusal contact, but surgical skeletal change.

CLINICAL RELEVANCE

Planned over-correction is a reasonable option for correction of severe shift or roll mandibular asymmetry in bimaxillary surgery for class III deformity.

The Effect of Zirconium Dioxide (ZrO2) Nanoparticles Addition on the Mechanical Parameters of Polymethyl Methacrylate (PMMA): A Systematic Review and Meta-Analysis of Experimental Studies

The number of studies on the subject of effects of zirconium dioxide (ZrO2) nanoparticles addition on the mechanical parameters of polymethyl methacrylate (PMMA) is still very limited. Therefore, in this research, the authors wanted to assess PMMA modified with the nano-ZrO2 additive in terms of changes in flexural, impact and tensile strength values in relation to PMMA without such component. A systematic review and meta-analysis were performed to evaluate the effect of incorporating nano-ZrO2 into PMMA on individual types of material strength. The obtained numerical data were tabulated and analyzed in the search for percentage changes in those parameters. It was then calculated for each set and the procured model was examined using residual sum of squares (RSS) to assess the discrepancy between the data and the estimation model whilst mean absolute deviation (MAD) was employed to determine robustness. The results of the systematic review were composed of data obtained from individual studies presented in eight independent articles. Overall, the addition of nano-ZrO2 increases the flexural strength of the composite with the PMMA matrix depending on the size of the ZrO2 grains administered. Unfortunately, these conclusions are based on a very limited amount of research and require further verification, especially regarding tensile strength.

Surgery-first orthognathic approach for the correction of facial asymmetry

We aimed to compare the reliability of the surgery-first approach and the traditional orthodontic-first approach for the correction of facial asymmetry based on the new classification of facial asymmetry. Patients with facial asymmetry who underwent orthognathic surgery between January 2016 and January 2019 were included. Cephalometric changes and relapse ratios were analyzed 12 months before and after surgery. Patients were divided into horizontal and vertical asymmetry groups based on the asymmetry vector, and subgroup analysis was conducted. The surgery-first approach without presurgical orthodontic treatment and the orthodontic-first approach showed a similar degree of asymmetry correction and skeletal stability. The relapse ratios of the maxilla height in the surgery-first and orthodontic-first groups were 0.25 ± 0.21 and 0.27 ± 0.25, respectively (p = 0.63), the relapse ratios of the maxilla width were 0.31 ± 0.32 and 0.21 ± 0.2, respectively (p = 0.14), the mandibular height relapse ratios were 0.34 ± 0.58 and 0.29 ± 0.36, respectively (p = 0.69), and the mandibular width relapse ratios were 0.12 ± 0.22 and 0.26 ± 0.31, respectively (p = 0.058). The treatment period of the surgery-first group (18.5 ± 5.3 months) was significantly shorter than that of the orthodontic-first group (22.9 ± 7.5 months, p = 0.024). Among the surgery-first group, patients with vertical asymmetry (15.0 ± 3.2 months) had a shorter treatment than those with horizontal asymmetry (21.6 ± 6.8 months, p = 0.006). Although contesting traditional standards is always challenging, the surgery-first orthognathic approach may lead to a new era in traditional orthognathic approaches. This new classification of facial asymmetry could be useful and practical when treating patients with facial asymmetry regardless of the etiology.

Orthodontic Treatment and Healthcare Goals: Evaluation of Multibrackets Treatment Results Using PAR Index (Peer Assessment Rating)

Background: The evaluation of orthodontic treatment outcomes using an objective method is important in order to maintain high treatment quality and final healthcare of patients. It allows professionals and university students to raise the level of the therapy. The aim of this study was to assess the orthodontic treatment outcomes in an Italian postgraduate School of Orthodontics using Peer Assessment Rating (PAR) Index. Methods: A sample of 50 patients treated in a postgraduate program was randomly selected. PAR index was used to assess pre-treatment and post-treatment study casts by two different examiners. The influence of different variables such as gender, treatment method, and need for extraction was statistically analyzed. Results: The average numerical reduction of PAR between the beginning and the end of the treatment was 18.74 (CI 95% 16.53–20.95), while the percentage reduction was 94.8% (CI 95% 91.91–97.68). All cases improved: 8% of patients resulted in the improved category, while 92% of them were in the greatly improved group. Conclusions: According to PAR index, the results showed that patients received a high-standard therapy. None of the factors studied influenced significantly the treatment outcomes.