Part 2: Is the maxillary canting and its surgical correction in patients with CFM correlated to the mandibular deformity?

Criterion Validity of the Newly Developed Occlusal Cant Index

OBJECTIVES

To assess the criterion-related (concurrent) validity of the newly developed occlusal cant index (OCI).

MATERIALS AND METHODS

Four standardized posterior-anterior (PA) cephalometric radiographs of four patients were obtained at a 0° occlusal cant (OC) and manipulated to create various degrees of OC from 1° to 4° on the right and left sides, with a total of 36 PA images. The angle between the actual horizontal line and the occlusal plane was manually drawn on each PA radiographic image. The set of radiographic images was displayed to 36 orthodontists, who were asked to measure the drawn angle and apply the OCI to each PA radiographic image.

RESULTS

The overall criterion-related validity of the OCI was statistically significant among all grades.

CONCLUSION

The OCI is highly valid and recommended for clinical consideration.

A decade of clinical research on clinical characteristics, medical treatments, and surgical treatments for individuals with craniofacial microsomia: What have we learned?

AIM

This article provides a review of a decade of clinical research studies on clinical features, medical interventions, and surgical interventions for individuals with craniofacial microsomia (CFM). We also provide recommendations for future clinical research.

METHOD

A systematic search of literature was conducted in Embase and PubMed/MEDLINE Ovid. All publications from 2010 to 2020 that included at least 10 individuals with CFM were considered relevant for this study.

RESULTS

A total of 91 articles were included. In the past decade, many new studies on CFM have been published providing more insight on the diagnosis and management of patients with CFM. This review encompasses findings on the clinical difficulties patients with CFM encounter, including the craniofacial and extracraniofacial characteristics of patients with CFM and its related clinical consequences on breathing, feeding, speech, and hearing.

CONCLUSIONS

A considerable number of large multicenter studies have been published in recent years, providing new insights in the clinical consequences of CFM. The phenotypic variety between patients with CFM makes patient-specific treatment tailored to individual needs essential. The research and development of clinical care standards might be challenging because of the heterogeneity of CFM. Future research on clinical and patient-reported outcomes can help identify optimal treatment strategies. Cooperation between craniofacial centers, using uniform registration and outcome measurement tools, could enhance research and future care for these patients.

LEVEL OF EVIDENCE

Level IV.

Displacement and stress distribution of the craniomaxillofacial complex under different surgical conditions: a three-dimensional finite element analysis of fracture mechanics

Objective

To provide a simplified treatment strategy for patients with maxillary transverse deficiency. We investigated and compared the fracture mechanics and stress distribution of a midline palatal suture under dynamic loads during surgically-assisted rapid palatal expansion.

Methods

Based on the cone-beam computed tomography (CBCT) data of a 21-year-old female volunteer, a three-dimensional model of the cranio-maxillofacial complex (including the palatal suture) was constructed. A finite element analysis model was constructed based on meshwork. After the yield strength of the palatal suture was set, an increasing expansion force (0–500 N) was applied within 140 ms to calculate the time–load curve, which mimicked nonsurgical bone expansion (model A). The same method was used to evaluate the fracture process, time and stress distribution of the palatal suture in maxillary lateral osteotomy-assisted (model B) and LeFort osteomy I (LFIO)-assisted expansion of the maxillary arch (model C).

Results

Compared with model A, the palatal suture of model B and model C showed a faster stress accumulation rate and shorter fracture time, and the fracture time of model B and model C was almost identical. Compared with model A, we discovered that model B and model C showed greater lateral extension of the maxilla, and the difference was reflected mainly in the lower part of the maxilla, and there was no difference between model B and model C in lateral extension of the maxilla.

Conclusions

Compared with arch expansion using nonsurgical assistance (model A), arch expansion using maxillary lateral wall-osteotomy (model B) or LFIO had a faster rate of stress accumulation, shorter time of fracture of the palatal suture and increased lateral displacement of the maxilla. Compared with arch expansion using LFIO (model C), arch expansion using lateral osteotomy (model B) had a similar duration of palatal suture rupture and lateral maxillary extension. In view of the trauma and serious complications associated with LFIO, maxillary lateral wall-osteotomy could be considered a substitute for LFIO.

Three-Dimensional Analysis of the Condylar Hypoplasia and Facial Asymmetry in Craniofacial Microsomia Using Cone-Beam Computed Tomography

PURPOSE

To assess the condylar hypoplasia and its correlation with craniofacial deformities in adults with unilateral craniofacial microsomia (CFM).

METHODS

Pretreatment cone-beam computed tomography scans of consecutive adults (mean age: 20.4 ± 3.0 years; range: 17.3 to 31.4 years) with Pruzansky-Kaban type I and IIA CFM were reconstructed in 3D. Both condyles were segmented. Asymmetry ratios (affected side/contralateral side) of condylar volume were calculated to indicate the extent of condylar hypoplasia. 3D cephalometry was performed to quantify the maxillomandibular morphology and facial asymmetry. The correlations in between were assessed by using Pearson's or Spearman's correlation coefficients.

RESULTS

Thirty-six subjects were enrolled, consisting of 22 subjects with Pruzansky-Kaban type I and 14 subjects with type IIA. The condyles in type IIA group were significantly more hypoplastic in height (asymmetry ratio: 40.69 vs 59.95%, P = .006) and volume (18.16 vs 47.84%, P < .001) compared to type I group. Type IIA group had a significantly smaller SNB value than type I group (72.94° vs 77.41°, P = .012), and a significantly greater facial asymmetry (P < .05). The hypoplastic extent of condylar volume and Pruzansky-Kaban types were significantly correlated with SNB (r = 0.457 and ρ = -0.411, respectively), upper incisor deviation (r = -0.446 and ρ = 0.362), chin deviation (r = -0.477 and ρ = 0.527), upper occlusal plane cant (r = -0.672 and ρ = 0.631), and mandibular plane cant (r = -0.557 and ρ = 0.357, P < .05).

CONCLUSION

For unilateral CFM adults, greater condylar hypoplasia in volume along with more severe mandibular retrusion and facial asymmetry objectively indicated a higher scale of Pruzansky-Kaban classification (type IIA). These quantitative distinctions are expected to enhance the diagnostic reliability of CFM.