Prediction of the Postoperative Bone Regeneration Rate After Mandibular Reduction: From the Perspective of Preoperative Inflammatory and Immune Status

BACKGROUND

Following mandibular reduction, bone regeneration in the angle region is a problem that can affect facial aesthetics and lead to revision surgery. The bone regeneration rate (BRR) varies between individuals and is difficult to predict. However, studies focusing on preoperative patient-related factors are lacking. As bone regeneration is closely related to the inflammatory and immune status of the organism, according to in vitro and in vivo evidence, preoperative inflammatory indicators were included in this study as potential predictors.

METHODS

Demographic and preoperative laboratory data were included as independent variables. The BRR calculated from computed tomography data was included as the dependent variable. Univariate analysis and multiple linear regression analysis were used to determine the key factors influencing the BRR. The ROC curves were used to analyse the corresponding predictive efficacy.

RESULTS

23 patients (46 mandibular angles) fulfilled the inclusion criteria. The mean bilateral BRR was 23.82 ± 9.90%. Preoperative monocyte count (M) was an independent positive factor for BRR, and age was a negative factor. Only M had a good predictive ability, and its optimal cut-off point to distinguish patients with BRR greater than 30% was 0.305 × 109/L. Other parameters were not significantly correlated with BRR.

CONCLUSIONS

Patient age and preoperative M may influence BRR, with M having a positive effect and age having a negative effect. According to the preoperative blood routine tests that are readily available, using the diagnostic threshold (M [Formula: see text] 0.305 × 109/L) derived from this study, surgeons can better predict BRR and identify patients whose BRR is greater than the mean level.

LEVEL OF EVIDENCE IV

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A Novel Cephalometric Approach Aiming to Quantify a Normal Range of Bony Chin Protrusion

Introduction

Cephalometric analysis is an essential tool in the diagnostics and planning of orthognathic surgery. No objective criterion exists to facilitate decision making regarding genioplasties. Differing opinions amongst clinicians therefore leads to wide variability amongst treatment options offered to potentially suitable patients. This study has three aims. The first was to quantify the distribution of chin morphology amongst the average population using cephalometric analysis. Secondly, we sought to determine whether cephalometric parameters could be used to predict overlying soft tissue changes. Lastly, we consider the use of a new cephalometric angle, BNPg, for pre- and post-operative assessment of genioplasty patients.

Methods

This study retrospectively analysed 231 lateral cephalograms. The angle between the landmarks: B point, Nasion and Pogonion was measured to generate 'BNPg' a novel unit to quantify bony chin protrusion.

Results

The mean BNPg from all 231 samples was 1.12 degrees with a standard deviation of ± 1.35. Comparison between sexes showed no significant differences between male and females (P = 0.108). Furthermore, bony chin protrusion was found to strongly positively correlate with soft tissue chin appearance (r = 0.731), however, BNPg was found not to correlate with skeletal malocclusion (ANB, r = 0.085).

Conclusion

The novel unit BNPg may serve as a useful tool in contributing to the determination of treatment thresholds in osseous genioplasty for desirable aesthetic outcomes and may be used post-operatively to assess outcomes also. As this is a pilot study, further clinical studies would be required to validate this parameter in genioplasty patients, both pre- and post-operatively.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12663-022-01784-5.

Retrospective study of long-term hard and soft tissue stability after advancement genioplasty with the use of rigid osteosynthesis

The main objective of this study was to evaluate long-term stability of rigid osteosynthesis in the context of advancement genioplasty. Bone stability was defined as a long-term bone loss of less than 2 mm. Measurements were performed on lateral cephalograms, in the sagittal and vertical planes, at three times: preoperative (T0, less than one month before surgery), early postoperative (T1, at least one month post-operatively) and late postoperative (T2, at least one year after surgery). 25 patients were included in the study, with a mean follow-up of 3.47 years (range 1-9.42 years). The mean sagittal bone advancement at T1 was 4.06 mm ± 1.34, with a bone loss of 0.65 mm at T2 (p = 0.001). The mean vertical bone movement was 1.25 mm ± 0.47 at T1, with a relapse at T2 of 0.34 mm (p = 0.27). The soft-to-hard tissue ratio was 78% in the sagittal plane. Rigid osteosynthesis offers long-term stability, with very little change in clinical outcome, in advanced genioplasty.

Intermaxillary elastics on skeletal anchorage and MARPE to treat a class III maxillary retrognathic open bite adolescent: A case report

Class III malocclusion when accompanied with transverse and vertical maxillomandibular discrepancies such as posterior crossbite and vertical open bite leads to complicated orthodontic treatment. Proper diagnosis and treatment planning are important in such patients for a successful orthodontic outcome. A common treatment approach for patients with class III malocclusion is to wait for the completion of growth and plan orthognathic surgery in conjunction with orthodontic treatment. However, performing no treatment and waiting for growth to be completed during teen years could lead to negative effects on the patient's self-esteem. In such cases, a non-surgical option with skeletal anchorage could be used to correct the malocclusion without surgical intervention. This case report shows that in patients with severe class III malocclusion, skeletal anchorage can be used for the correction of anterior crossbite with intermaxillary elastics.

First premolar extractions in an adolescent presenting a Class I biprotrusion malocclusion with skeletal Class II: A case report

This case report shows the orthodontic treatment of four first premolar extractions of a 14-year-old teenager presenting a dental Class I malocclusion with a severe retrognathic mandible. It reflects conflicting views on objectives between the orthodontist who takes into account the facial balance and the patient who only desires a tooth alignment.

Diagnosis and Innovative Multidisciplinary Management of Hallermann-Streiff Syndrome: 20-Year Follow-Up of a Patient

Hallermann-Streiff syndrome (HSS) is a rare congenital disorder that mainly affects head and face development. We described the different patterns of the disease throughout the whole growth period and provided innovative treatment steps. Indeed, early genioplasty and dental implantation before growth completion were performed. These steps allowed to improve facial growth and to provide orthodontic anchorage, respectively. Complementary orthognathic surgery achieved satisfactory occlusion and refined aesthetics. We believe such an approach could be considered as a relevant treatment modality to complete multidisciplinary care in patients with HSS.

Fixed-functional appliance treatment combined with growth hormone therapy

The purpose of this study was to illustrate the effects of growth hormone (GH) therapy and fixed functional appliance treatment in a 13-year-old Class II malocclusion patient without GH deficiency. GH has been shown to effectively increase endochondral growth and induce a more prognathic skeletal pattern. Although a major concern in Class II retrognathic patients is chin deficiency, long-term studies have shown that the mandibular growth enhancement effects of functional appliances are clinically insignificant. This case report demonstrates that the mandible grew significantly during fixed functional appliance treatment combined with GH therapy, with stable results during 2 years 11 months of retention. More studies are needed to evaluate GH therapy as a supplement in Class II treatment.

[Aesthetic success in genioplasties procedures criteria]

Maxillomandibular dysmorphia may be associated with structural chin pathologies. Three-dimensional jaws displacements have limits. Specific genioplasty is an additional surgical mean for soft tissues profile normalization. Osteotomy line is examined according an incline angle and a possible lateral extension, as chin wing technique, improves facial shape. Cephalometric set-up with R line analyzes surgical chin movements and impact of lower incisors labial inclination on lower lip and mentolabial fold after advancement genioplasty. Micro-implant anchorage is a precious help to find lower incisors good position and optimum lower occlusal plane frontal shift in asymmetric facial pattern. Orthodontics criteria are essential factors to access an aesthetic success in genioplasties procedures.

Impact of genioplasty during puberty on the upper airways

AIM

Mouth breathing is a functional disorder that affects craniofacial and dento-alveolar growth and also upper airway (UA) anatomy. This is apparent mainly in dimensional abnormalities of the UA caused by hypertrophy of Waldeyer's ring and excessive vertical development of the lower part, giving rise to labial incompetence that perpetuates the functional disorder. The main aim of this study was to evaluate the development of the oropharyngeal structures in young hyperdivergent patients who had undergone functional genioplasty in the context of orthodontic treatment.

METHODS

This is a comparative retrospective study performed on 47 adolescents who were hyperdivergent, non-obese and exclusive or diurnal mouth breathers, treated at the Centre de soins, d'enseignement et de recherche dentaires (CSERD) in Montpellier, France. All were candidates for early genioplasty for vertical reduction, and were undergoing or at the end of treatment: 23 had been treated surgically (functional genioplasty), and 24 controls had received orthodontic treatment alone. Inter-group comparison of the changes in cephalometric measurements of the oro- and nasopharyngeal zones and maxillomandibular measurements was performed using covariance analysis (ANCOVA) to adjust for confounding factors.

RESULTS

Concerning the skeletal structures: in the sagittal dimension, genioplasty led to significantly greater projection of the symphysis in the surgical group than in the control group (P<0.001). However, the sagittal position of the hyoid bone was unchanged. Similarly, in the vertical dimension, the reduction in divergence of the bony base was significantly greater in the surgical group (P<0.001), but with no change in the vertical position of the hyoid bone. Concerning the upper airways: at the level of the nasopharynx, there was a significantly greater increase in the velopharyngeal space in the surgical group (P<0.033). The same observation can be made on the level of the oropharynx, where there was a significant increase in the linguopharyngeal space in the surgical group (P<0.05), which was not the case in the control group. The change in the depth of the pharynx did not differ significantly between the two groups.

CONCLUSION

Early genioplasty performed on adolescents during the growth phase helps to recalibrate the UA by encouraging spontaneous lip closure.

Combined surgical-orthodontic treatment: how did it evolve and what are the best practices now?

It has been 50 years since the landmark presentation by Hugo Obwegeser at Walter Reed Army Hospital. At that conference, Professor Obwegeser offered American surgeons techniques to correct facial skeletal deformities with access through intraoral incisions. As important advances in surgical technique and anesthesia evolved for the surgical procedures, a major contribution by American orthodontists in collaboration with surgeons was the creation of a common diagnostic, planning, and treatment scheme for use by both clinician groups in the treatment of dentofacial deformities, the skeletal and dental problems of the most severely affected 5% of the population. This article summarizes what American orthodontists and surgeons have learned in the late 20th and early 21st centuries, and forecasts what might be the future of treatment for patients with dentofacial deformities.