Evaluation of Different Restoration Combinations Used in the Reattachment of Fractured Teeth: A Finite Element Analysis

An assessment of Brazilian dentists' knowledge about tooth fragment reattachment: A cross-sectional study

BACKGROUND/AIM

Crown fractures are common traumatic dental injuries and tooth fragment reattachment is a viable option for restoring a fractured tooth. The aim of this study was to assess the knowledge and experience of dentists in the Federal District regarding the tooth fragment reattachment technique for enamel and dentin fractures.

MATERIALS AND METHODS

For the cross-sectional observational study, an electronic form was designed with objective and self-report questions for dentists. The data were analyzed using descriptive statistics, with their absolute and relative frequencies. For the analysis of categorical variables, the nonparametric chi-squared or Fisher exact association tests were used in the statistical software R (version 4.2.1).

RESULTS

A total of 416 dentists participated in the study (58.9% female and 41.1% male). Of these, 70% declared they knew about fragment reattachment, but only 42.3% reported previous experience with this procedure. The most common storage medium used for the fractured fragment was milk (78.1%), and the bonding material used for reattachment was light-cured composite resin (86.3%). A majority (66.3%) reported that for a patient with enamel and dentin fracture, with the crown fragment in good condition, they would choose to do the reattachment.

CONCLUSION

Dentists demonstrated that they had adequate knowledge about the tooth fragment technique, although many did not have previous experience with this procedure.

Methods and applications of finite element analysis in dental trauma research: A scoping review

Finite Element Analysis (FEA) is vital for understanding dental traumatology (DT) biomechanics, aiding diagnosis, treatment planning, and outcome prediction. This review explores FEA applications in DT research, evaluates their quality and outcomes, and assesses methodological aspects. Accordingly, recommendations for future researchers are provided. The study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for scoping reviews and registered in Open Science framework. A comprehensive search using relevant text-words and MeSH terms was performed in established databases. The inclusion criteria encompassed all Finite element analysis (FEA)-based Dental traumatology (DT) studies without language or publication year restrictions. Risk of bias was assessed with the Risk of bias tool for the use of finite element analysis in dentistry (ROBFEAD) tool. Forty-six studies published from 2001 to 2023 were included in the qualitative synthesis. The studies were categorized into five domains and six subdomains based on objectives. Maxillary central incisors and surrounding structures were commonly modelled (n = 27). Most studies utilized Computed tomography (CT), Cone Beam CT, or micro CT. Traumatic injury forces ranged from 100 N to 2000 N, and occlusal forces ranged from 150 N to 350 N. All studies were rated as high risk of bias. Fory-six studies were categorized, with most focusing on stress distribution and fracture patterns in dento-alveolar structures under various conditions, while few assessed displacements. Methodological quality lacked robustness in model development and substructure properties. Future studies should address these limitations and enhance reporting practices.

Comparative biomechanics of all-on-4 and vertical implant placement in asymmetrical mandibular: a finite element study

BACKGROUND

Clinical scenarios frequently present challenges when patients exhibit asymmetrical mandibular atrophy. The dilemma arises: should we adhere to the conventional All-on-4 technique, or should we contemplate placing vertically oriented implants on the side with sufficient bone mass? This study aims to employ three-dimensional finite element analysis to simulate and explore the biomechanical advantages of each approach.

METHODS

A finite element model, derived from computed tomography (CT) data, was utilized to simulate the nonhomogeneous features of the mandible. Three configurations-All-on-4, All-on-5-v and All-on-5-o were studied. Vertical and oblique forces of 200 N were applied unilaterally, and vertical force of 100 N was applied anteriorly to simulate different masticatory mechanisms. The maximum von Mises stresses on the implant and framework were recorded, as well as the maximum equivalent strain in the peri-implant bone.

RESULTS

The maximum stress values for all designs were located at the neck of the distal implant, and the maximum strains in the bone tissue were located around the distal implant. The All-on-5-o and All-on-5-v models exhibited reduced stresses and strains compared to All-on-4, highlighting the potential benefits of the additional implant. There were no considerable differences in stresses and strains between the All-on-5-o and All-on-5-v groups.

CONCLUSIONS

With the presence of adequate bone volume on one side and severe atrophy of the contralateral bone, while the "All-on-4 concept" is a viable approach, vertical implant placement optimizes the transfer of forces between components and tissues.

Stresses in teeth with External Cervical Resorption defects restored with different Biomimetic cements: A Finite Element Analysis

INTRODUCTION

This study compared the stress distributions in teeth with simulated external cervical resorption defects restored with different restorative materials and identified areas of high stress concentration.

METHODS

A maxillary central incisor created in a scanned model using HyperWorks software served as control. External cervical resorption defects based on Shanon Patel's classification were created (1Bd/2Bd/3Bd) in the scanned model. The defects were restored using Mineral Trioxide Aggregate (MTA), Biodentine, Glass Ionomer Cement (GIC) and Bioaggregate. On all the models a force of 100 N was applied on palatal aspect, 2 mm incisal to cingulum directed at 45° along the long axis of the tooth.

RESULTS

The stresses generated in dentin and cementum is less, with a restorative material having high Young's modulus. For 1Bd defect, MTA and Bioaggregate showed least stresses in dentin and cementum respectively, whereas Biodentine had consistently lower stresses in dentin and cementum both. Larger defects like 2Bd and 3Bd restored with Bioaggregate exhibited minimum stresses in dentin and cementum.

CONCLUSION

Bioaggregate and Biodentine replace dentin with maximum stress and maximum strain. Elastic moduli similar to or higher than dentin are preferred for restoring cervical third resorptive lesions of the tooth.

Evaluation of stress and strain on mandible caused using “All-on-Four” system from PEEK in hybrid prosthesis: finite-element analysis

Hybrid prostheses have recently been used as suitable treatment alternatives for edentulous individuals to restore the mastication mechanism. These prostheses utilize “All on four” concept, in which four implants are inserted into the jaw bone, and supported by a bar. Titanium is usually used in the fabrication of “All on four” parts due to its good mechanical properties. However, it has many drawbacks including esthetic impairment, casting issues, hypersensitivity reactions, stress shielding, and incompatibility with imaging techniques. These drawbacks have prompted researchers to find alternative materials (e.g., polymers). Recently, the new polymeric material PEEK has a major role in dentistry, due to its biocompatibility, shock-absorbing ability, and good mechanical properties. This work used the finite-element method to conduct stress–strain analysis on mandible rehabilitated with a hybrid prosthesis, using PEEK in the fabrication of “All on four” parts instead of titanium, using different densities of spongy bone. As the density of spongy bone is expected to influence the choice of “All on four” fabrication material. A 300 N vertical force was applied unilaterally, bilaterally, and anteriorly to stimulate the different mastication mechanisms. The results illustrated that PEEK material reduced the stresses and strains on bone tissues and increased the mucosal stress, compared to titanium. Consequently, this material was recommended to be used in the fabrication of “All on four” parts, especially in the low-density model. However, further research on PEEK implants and abutments is required in near future.