Functional stability analyses of maxillofacial skeleton bearing cleft deformities

Abstract

The symmetrically stable craniofacial bony structure supports the complex functions and delicate contour of the face. Congenital craniofacial deformities are often accompanied by bony defects and have been repetitively correlated with compromised dento-maxillary stability, but neither the extent nor the pattern of cleft-related maxillary instability has been explored in detail. Furthermore, it is largely unknown if the bony defect and related instability are correlated with secondary maxillary deformity common among patients with orofacial clefts. With the aid of finite element modeling, we studied the detailed relationship between cleft-related bony defect and maxillary stability under occlusal loading. Craniofacial models were generated based on cone-beam computed tomography data and loaded with mimicked bite forces along the axial axis of each tooth. Our data showed that all cleft models exhibited more asymmetrical deformations under mastication compared with the normal. Models with palatal cleft demonstrated greater asymmetry, greater dental arch contraction, and less maxillary protrusion compared to models with alveolar cleft only. For unilateral cleft models, alveolus on non-cleft side tended to be more protruded and lifted than the cleft side. For bilateral cleft models, the most prominent feature was the seriously contracted alveolar arch and curved and pitched premaxillae. These findings indicated cleft type-specific pattern of maxillary instability, which were largely in accordance with dentoalveolar morphological features among patients. Collectively, our study elucidated the detailed relationship between cleft bony defect and the pattern of maxillary instability, and suggested a prototype for studying the abnormal maxillary and dental arch growth among patients with craniofacial deformities.

Three-dimensional finite element analysis of the effect of alveolar cleft bone graft on the maxillofacial biomechanical stabilities of unilateral complete cleft lip and palate

“…Approximately 75% of patients with cleft lip and palate have varying degrees of alveolar cleft [ 20 ]. UCLP (Unilateral Cleft Lip and Palate) deformity has a significant impact on the bone morphology of the mid-facial and oronasal regions [ 21 ], the alveolar process on the non-cleft side is more prominent and protuberant than that on the cleft side [ 2 ]. There are asymmetrical bone movements in UCLP due to the special maxillofacial structure [ 22 ], loss of bone and soft tissue on the cleft side and tension of the repaired lip on the non-cleft side can lead to flattening and recession of the central face [ 23 ].…”

“…Based on epidemiological statistics, Nagase et al [ 1 ] found UCCLP (unilateral complete cleft lip and palate) to be the most prevalent type of cleft lip and palate. For patients with UCCLP, the two parts of the maxilla divided by the cleft are also different [ 2 ],the asymmetry of the nasomaxillary complexes [ 3 , 4 ] and the congenital sagittal asymmetric defect of the maxilla with collapsed bone segment deformity [ 5 ] on the cleft side are the common clinical manifestations. According to the summary by Janovica et al [ 6 ], the occlusal forces of the dentition formed the specific bony conduction trajectories along the thickened buttresses of the maxillofacial bones, comprising a total of 7 vertical buttresses (bilateral nasomaxillary, zygomaticomaxillary, pterygomaxillary buttresses and the median sagittal buttress) and 3 horizontal buttresses (bilateral prefrontal, zygomatic and maxillary buttresses) to transmit the majority of occlusal loads.…”

“…The photoelastic technique also revealed that 3 main stress trajectories existed in the facial region, namely the nasomaxillary, zygomaticomaxillary and pterygomaxillary trajectories [ 7 ]. The facial functional system was in the mechanical equilibrium between the dentition, muscles and bones [ 8 ], the instability of the maxillary segments caused by the maxillary buttress defect could lead to the secondary collapse and displacement of the maxilla [ 2 ]. On one hand, the cleft of the UCCLP can destroy the integrity of maxillofacial bone structures and interrupt the physiological occlusal stress transmission; on the other hand, the cleft is located on one side of the midline, the mechanical balance is lost and the stability of the maxillofacial structures will be affected, which in turn has a negative impact on the growth and development of the maxillofacial region.…”

Craniofacial Growth Analysis of Individuals With and Without Cleft Lip and Palate in Colombia

“…Another reason why the growth of the middle facial third in patients with CLP may be altered is the bone asymmetry of the upper maxilla caused by a cleft. Asymmetric deformation is produced during mastication and deviation of occlusal forces in the cranio-maxillo-facial complex as well as different types of mastication between unilateral and bilateral patients with CLP, causing asymmetric stimuli in growth areas and inducing changes in the development of the maxillofacial complex (Luo et al, 2019). This finding is related to the differences in craniofacial growth and development observed in this study.…”

Problems following topic shift in interactions with repaired cleft children

“…Cleft lip and/or palate (CL/P) is the most common birth defect around the world (Xiangyou et al, 2019). The occurrence is recorded to generally impact one in every 700 live births worldwide but cleft cases in South-East Asian countries seem to be higher where the prevalence is between 1.1 and 1.9 per 1000 live births (Abumustafa et al, 2019).…”