Asymmetric Maxillary Protraction for Unilateral Cleft lip and Palate Patients Using Finite Element Analysis

Systematic Review and Critical Appraisal of the Evidence Base for Nasoalveolar Molding (NAM)

OBJECTIVE

To critically appraise the body of scientific literature supporting the risks and efficacy of nasoalveolar molding (NAM), specifically in contrast to alternative methods of presurgical infant orthopedics (PSIO) or to treatment without PSIO.

MAIN OUTCOME MEASURES

Five outcome domains were considered: nasolabial aesthetics; dentoalveolar relationship; midfacial growth; cost and burden of care; and number of anesthetic events.

DESIGN

MEDLINE, Embase, and Scopus were queried for articles from the first description of the Grayson-Santiago NAM technique (1993) through December 13, 2021. After the application of inclusionary and exclusionary criteria, selected articles were critically appraised using a systematic framework that included risk of bias assessment using the Cochrane RoB 2.0 and ROBINS-I tools.

RESULTS

A total of 88 studies were included. Level-I and -II evidence showed on par or better approximation and alveolar alignment achieved by NAM compared to other PSIO. Level-II and -III evidence showed improved nasolabial aesthetics compared to other PSIOs. Level-II and -III evidence supported no harm to maxillofacial skeletal growth through age 12. Sparse level-III evidence supported a reduced number of labial or nasal revisions following NAM. Level-II and -III evidence showed NAM requiring upfront cost and frequent appointments but reducing caregiver psychosocial burden and reducing long-term costs compared to select alternatives. Many studies carried a high risk of bias.

CONCLUSIONS

Current evidence supports the overall efficacy of NAM regarding short/mid-term outcomes, with a low risk of negative effects on midfacial growth or dental development. The high risk of bias discovered in many papers underscores the need for robust study design in future research.

Arch Symmetry in Patients Without and With Cleft Lip and Palate After Orthodontic/Rehabilitative Treatment-A Stereophotogrammetry Study

To evaluate and compare the dental arch symmetry of individuals with and without cleft lip and palate after orthodontic/rehabilitation treatment.

Cross-sectional study.

Tertiary cleft center in Brazil.

Fifty-five participants aged between 18 and 30 years were divided into 3 groups according to treatment. Patients that received either a fixed partial denture (FPD) or implant-supported crown (ISC) in the cleft area or only orthodontic treatment, noncleft patients (NC).

An analysis was performed using digitized dental casts scanned by laser and software. The following linear measurements were evaluated: incisor-canine; canine-molar; incisor-molar; surface and volume of the palatal region.

Three-way ANOVA was used to compare the study factors: group (FPD/ISC/NC) and side (right/left) followed by the Tukey test to verify their interaction (α = .05).

The results showed statistically significant differences among groups for the maxillary linear measurements canine-molar and incisor-molar, but not for incisor-canine. No statistically significant differences were found regarding the side for the maxillary measurements, while the factor interaction showed similarity only for incisor-canine. The mandibular measurements showed no statistical differences among groups, sides, or factor interactions. In surface and volume, all values in patients with cleft presented lesser than in without cleft patients.

Regardless of the rehabilitation, arch symmetry can be achieved in the incisor-canine dimension in the cleft area.

Finite element analysis of sagittal screw expander appliance in the treatment of anterior maxillary hypoplasia

The skeletal anterior crossbite is a common malocclusion in clinic. However, there have been no reports on the maxillary sagittal expansion to correct the premaxillary hypoplasia, which greatly influences the facial morphology and masticatory function, using finite element analysis. In the present study, a three-dimensional finite element model of craniomaxillofacial complex with maxillary sagittal hypoplasia is constructed and the treatment for premaxillary hypoplasia by the sagittal screw expander appliance is simulated. The hypoplasia of the left premaxilla is more serious than that of the right and thus the size of the left part of premaxillary expander baseplate is designed to be larger than that of the right part and the loading is applied at 10° leftward to the sagittal plane and 30° forward and downward to the maxillary occlusal plane. The displacements or equivalent stress distributions of the maxilla, teeth and their periodontal ligaments, are analyzed under the loads of 5.0 N, 10.0 N, 15.0 N, and 20.0 N. Consequently, as the load increases, the displacements or equivalent stresses of the maxilla, teeth and their periodontal ligaments all increase. Almost the whole premaxilla markedly move forward, downward, and leftward while other areas in the craniomaxillofacial complex remain almost static or have little displacement. The equivalent stress concentration zone of the maxilla mainly occurs around and in front of the incisive foramina. The displacements of left premaxilla are generally greater than those of the right under the loading forces. The maximum equivalent stress on the teeth and their periodontal ligaments are 2.34E-02 MPa and 2.98E-03 MPa, respectively. Taken together, the sagittal screw expander appliance can effectively open the premaxillary suture to promote the growth of the premaxilla. An asymmetrical design of sagittal screw expander appliance achieves the asymmetric expansion of the premaxilla to correct the uneven hypoplasia and obtains the more symmetrical aesthetic presentation. This study might provide a solid basis and theoretical guidance for the clinical application of sagittal screw expander appliance in the efficient, accurate, and personalized treatment of premaxillary hypoplasia.

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

BACKGROUND

The objective is to clarify the effect of alveolar cleft bone graft on maxillofacial biomechanical stabilities, the key areas when bone grafting and in which should be supplemented with bone graft once bone resorption occurred in UCCLP (unilateral complete cleft lip and palate).

METHODS

Maxillofacial CAD (computer aided design) models of non-bone graft and full maxilla cleft, full alveolar cleft bone graft, bone graft in other sites of the alveolar cleft were acquired by processing the UCCLP maxillofacial CT data in three-dimensional modeling software. The maxillofacial bone EQV (equivalent) stresses and bone suture EQV strains under occlusal states were obtained in the finite element analysis software.

RESULTS

Under corresponding occlusal states, the EQV stresses of maxilla, pterygoid process of sphenoid bone on the corresponding side and anterior alveolar arch on the non-cleft side were higher than other maxillofacial bones, the EQV strains of nasomaxillary, zygomaticomaxillary and pterygomaxillary suture on the corresponding side were higher than other maxillofacial bone sutures. The mean EQV strains of nasal raphe, the maximum EQV stresses of posterior alveolar arch on the non-cleft side, the mean and maximum EQV strains of nasomaxillary suture on the non-cleft side in full alveolar cleft bone graft model were all significantly lower than those in non-bone graft model. The mean EQV stresses of bilateral anterior alveolar arches, the maximum EQV stresses of maxilla and its alveolar arch on the cleft side in the model with bone graft in lower 1/3 of the alveolar cleft were significantly higher than those in full alveolar cleft bone graft model.

CONCLUSIONS

For UCCLP, bilateral maxillae, pterygoid processes of sphenoid bones and bilateral nasomaxillary, zygomaticomaxillary, pterygomaxillary sutures, anterior alveolar arch on the non-cleft side are the main occlusal load-bearing structures before and after alveolar cleft bone graft. Alveolar cleft bone graft mainly affects biomechanical stabilities of nasal raphe and posterior alveolar arch, nasomaxillary suture on the non-cleft side. The areas near nasal floor and in the middle of the alveolar cleft are the key sites when bone grafting, and should be supplemented with bone graft when the bone resorbed in these areas.

A Three-Dimensional Finite Element Analysis of Displacement and Stress Distributions of Unilateral and Bilateral Cleft Lips by Using Developed Pre-Surgical Treatment Architecture

Cleft lips and cleft palates are the most common birth defects in newborns. Pre-surgical correction of unilateral and bilateral cleft lips and palates has been the subject of interest of many previous works. This condition has necessitated the evolution of many surgical and non-surgical techniques to mitigate the problem of this deformity in children. In this study, we proposed a new architecture that can be used instead of the conventional pre-surgical treatment. The proposed architecture has mechanical and electronic parts. This architecture was adopted to apply external stress to the cleft bones and cleft edges using an airbag that is located in the mechanical part. The amount of air in the airbag can be controlled by an available control unit in the electronic part. The effect of external stress on the cleft bones and the cleft edges was analyzed by using the finite element analysis (FEA) method. The FEA study aimed to analyze the displacement, amount of tensile and compressive forces, and Von Mises stress distributions on the cleft bones, cleft edges, nasal septum, and superior alveolar part of the maxillary jaw of unilateral and bilateral cleft models during pre-surgical treatment with the novel architecture. The results show that displacement and stress affected the clefts of both models. Displacement had a significant effect of gradually bringing the clefts closer to each other and returning them to the posterior. The analysis also investigated the effects of stress on the cleft bone and cleft edge. It was found from the results that the stresses helped to bring the incisions closer to the most appropriate position for plastic surgeons. The results prove that the positive and negative X-displacements move in the opposite direction, which means that the cleft edges gradually converge toward each other. Moreover, the negative Z-displacement affected the movement of cleft bones and cleft edges from outside to inside and gradually returned them to a suitable position. The findings show that the proposed architecture can be contributed to the pre-surgical treatment of the unilateral and bilateral clefts as an alternative to the traditional method.

Arch Asymmetry in Patients With Cleft Lip and Palate After Rehabilitation Treatment Using Stereophotogrammetry

ABSTRACT

Arch asymmetry in cleft patients is a current problem that interdisciplinary treatment aims to solve. This research proposed to analyze the final rehabilitation, according to the arch symmetry of these patients. Thirty-five patients aged between 18 and 30 years, rehabilitated with a fixed partial denture or implants in the cleft area. The analysis was performed using digitalized dental casts with a laser model scanner (R700TM; 3Shape A/S, Holmens Kanal 7, 1060, Copenhagen/Denmark), analyzed with a Vectra Analysis Module software program (VECTRA H1; Canfield Scientific, 4 Wood Hollow Road, Parsippany, NJ 07054). Three linear measurements were evaluated, incisal-canine, canine-molar, and incisal-molar distance. The Student t test was applied to test the significance (P = 0.05) of an observed sample by correlation coefficient test (r-value). Female patients showed a significant correlation in arch symmetry. According to the rehabilitation treatment, patients who received implants showed a high correlation and significant symmetry at all maxillary distances. Finally, according to the cleft side in the maxillary dimensions, even though the majority of patients had clefts on the left side, only patients with a cleft on the right side showed symmetry in this area. Patients rehabilitated with implants in the cleft area showed a more symmetrical maxillary arch than those restored with fixed partial dentures.

Biomechanical behavior of an alveolar graft under maxillary therapies

Cleft lip and palate is a congenital defect that affects the oral cavity. Depending on its severity, alveolar graft surgery and maxillary orthopedic therapies must be carried out as a part of the treatment. It is widely accepted that the therapies should be performed before grafting. Nevertheless, some authors have suggested that mechanical stimuli such as those from the maxillary therapies could improve the success rate of the graft. The aim of this study is to computationally determine the effect of maxillary therapies loads on the biomechanical response of an alveolar graft with different degrees of ossification. We also explore how the transverse width of the cleft affects the graft behavior and compare results with a non-cleft skull. Results suggest that stresses increase within the graft as it ossifies and are greater if maxillary expansion therapy is applied. This has consequences in the bone remodeling processes that are necessary for the graft osseointegration. Maxillary orthopedic therapies after graft surgery could be considered as a part of the treatment since they seem to act as a positive extra stimulus that can benefit the graft.

Three-dimensional finite element analysis of initial displacement and stress on the craniofacial structures of unilateral cleft lip and palate model during protraction therapy with variable forces and directions

Maxillary protraction and expansion is recommended to treat midfacial deficiency in patients with cleft lip and palate (CLP), where amount and direction of forces can change displacement and stress. This study assessed the initial displacement and stresses using Facemask and Maxgym forces with and without RME at +20^∘, 0^∘, and -20^∘ angulation using a finite element (FE) model of unilateral cleft lip and palate (UCCLP). The Initial displacement and stress were more for protraction with expansion as compared to only protraction. Asymmetric displacement was observed with more on cleft than on noncleft side and more on dental than skeletal structures. Palatal plane rotated less upward, increased arch width and decreased arch length was observed with protraction with expansion.

Deformation of the zygomaticomaxillary and nasofrontal sutures during bone-anchored maxillary protraction and reverse-pull headgear treatments: An ex-vivo study

INTRODUCTION

Bone-anchored maxillary protraction (BAMP) is an emerging treatment that involves applying a protraction load to the maxillary bone. Although it is believed that such an approach results in better sutural separation, this has not been investigated. This study aimed to assess and compare the deformation of 1 circumaxillary suture (zygomaticomaxillary suture [ZMS]) and 1 facial suture (nasofrontal suture [NFS]) during BAMP and reverse-pull headgear (RPHG) treatment.

METHODS

The study was performed ex vivo on 15 pig heads. Miniplates were placed in the maxillary bone and the body of the mandible. A molar tube was bonded to the maxillary first molars. Six single-element strain gauges and 3 differential variable reluctance transducers were installed across the ZMS and NFS bilaterally. Each head underwent BAMP and RPHG unilaterally and bilaterally.

RESULTS

In unilateral experiments, both BAMP and RPHG resulted in tension on the ipsilateral ZMS and NFS and compression on the contralateral side, with higher magnitude in the BAMP group. In bilateral experiments, both modalities resulted in tension at the ZMS, with higher magnitude in the BAMP group. Deformation of the NFS was different between the 2 groups: tension in majority of the BAMP and compression in most of the RPHG heads.

CONCLUSIONS

Our study shows a higher magnitude of sutural separation in BAMP than in RPHG. The pattern of sutural deformation is consistent with a forward displacement of the midface in BAMP compared with an upward and backward rotation in the RPHG. Rotation of the maxilla was also present in some of the subjects who underwent BAMP.