Direct restoration modalities of fractured central maxillary incisors: A multi-levels validated finite elements analysis with in vivo strain measurements

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.

Efficacy of bio-activated anti-calculus toothpaste on oral health: a single-blind, parallel-group clinical study

BACKGROUND

Current epidemiologic studies have confirmed the widespread presence of calculus in teenagers and adults of all ages. Among the multiple anti-calculus strategies that have been proposed over the years inhibition of crystal growth has been the most attractive. Current formulations in anti-calculus toothpastes and mothwash, utilise either hydroxyapatite or various pyrophosphate combinations. This study aimed to analyze the efficacy of an anti-calculus tooth paste in combination or not with a mouth rinse.

PATIENTS AND METHODS

Patients (totally 40) used a pyrophosphate-based toothpaste containing Tetrapotassium Pyrophosphate, Pentasodium Triphosphate, Xylitol, Hydroxyapatite, Citric Acid, And Calcium Carbonate (Group A) in combination, with a mouth rinse containing an association of Pentasodium Triphosphate, Tetrapotassium Pyrophosphate and Citric Acid (Group B). A range of parameters were measured for: saliva pH, Volpe Manhold Calculus Index (VMI), Gingival Index (GI), and Plaque Index (PI).

RESULTS

The test mouth rinse Group B showd reductions in VMI, GI, PI, and increases in pH levels, after using the combination of toothpaste and mouth rinse. No changes to the mucosa or teeth were observed in both Groups. Patients perceived that the comitation of products was more effective.

CONCLUSIONS

The results from the three-month calculus examination indicated that both the tested products, modified positively clincal parameters and salivary pH. Moreover, the use of the tested products was not associated with any adverse effects.

Bioresorption Control and Biological Response of Magnesium Alloy AZ31 Coated with Poly-β-Hydroxybutyrate

Magnesium and its alloys are not normally used as bioresorbable temporary implants due to their high and uncontrolled degradation rate in a physiological liquid environment. The improvement of corrosion resistance to simulated body fluids (SBF) of a magnesium alloy (AZ31) coated with poly-β-hydroxybutyrate (PHB) was investigated. Scanning electron microscopy, Fourier transform infrared spectrometer, and contact angle measurements were used to characterize surface morphology, material composition, and wettability, respectively. pH modification of the SBF corroding medium, mass of Mg2+ ions released, weight loss of the samples exposed to the SBF solution, and electrochemical experiments were used to describe the corrosion process and its kinetics. The material’s biocompatibility was described by evaluating the effect of corrosion by products collected in the SBF equilibrating solution on hemolysis ratio, cytotoxicity, nitric oxide (NO), and total antioxidant capacity (T-AOC). The results showed that the PHB coating can diffusively control the degradation rate of magnesium alloy, improving its biocompatibility: the hemolysis rate of materials was lower than 5%, while in vitro human umbilical vein endothelial cell (HUVEC) compatibility experiments showed that PHB-coated Mg alloy promoted cell proliferation and had no effect on the NO content and that the T-AOC was enhanced compared with the normal group and bare AZ31 alloy. PHB-coated AZ31 magnesium alloy extraction fluids have a less toxic behavior due to the lower concentration of corrosion byproducts deriving from the diffusion control exerted by the PHB coating films both from the metal surface to the solution and vice versa. These findings provide more reference value for the selection of such systems as tunable bioresorbable prosthetic materials.

A comparative evaluation of the fracture resistance of endodontically treated teeth with simulated invasive cervical resorption cavities restored with different adhesive restorative materials: An in vitro study

Aim:

The aim of the study was to compare the fracture resistance of endodontically treated teeth with simulated invasive cervical resorption cavities, restored with different restorative materials, namely, conventional glass-ionomer cement (CGIC), resin-modified glass-ionomer cement (RMGIC), flowable composite (FC), and giomer.

Methods:

Sixty extracted human permanent maxillary central incisor teeth were assigned to six groups,which were, Group 1 (intact teeth, control), Group 2 (teeth with biomechanical preparation and resorption cavity), Group 3 (CGIC), Group 4 (RMGIC), Group 5 (FC), and Group 6 (giomer). Except for Group 1, other groups were subjected to endodontic treatment. Teeth of Group 2 were left unobturated and teeth of Groups 3–6 were obturated. A simulated resorption cavity was prepared labially in the specimens belonging to Groups 2–6 and restored with respective restorative materials. The specimens were subjected to compressive load until failure in an Instron testing machine and the load at failure was recorded in Newtons.

Statistical Analysis:

The data obtained were statistically analyzed using one-way ANOVA, pair-wise comparison was made with Tukey's multiple comparison test, and P < 0.05 was considered statistically significant.

Results:

There was a statistically significant difference in the fracture resistance of intact teeth and endodontically treated teeth with simulated invasive cervical resorption cavities restored with different adhesive restorative materials. Among the restored teeth, there was no significant difference.

Conclusion:

Intact teeth were found to have the highest resistance to fracture followed by those restored with giomer, FC, RMGIC, and CGIC in that order.

[Three-dimensional finite element analysis of different endodontic access methods and full crown restoration in the maxillary central incisor]

OBJECTIVE

This study evaluates the effects of different endodontic access methods and full-ceramic crown on the stress distribution in the maxillary central incisor by using three-dimensional finite element analysis.

METHODS

Computed tomography scans of the maxillary central incisor were used to construct a three-dimensional finite element model of the maxillary central incisor. According to the different methods of endodontic and the prosthetic treatments, four models were established, namely, group A (traditional access cavity preparation with resin filling), group B (traditional access cavity preparation restored full-ceramic crown), group C (minimally invasive endodontics with resin filling) and group D (minimally invasive endodontics restored full-ceramic crown). A static force of 100 N and a direction of 45° was applied to the long axis of the tooth at the junction of the incisal section one-third and middle section one-third. The maximum principal stress, the von Mises stress and the modified von Mises stress of the tooth tissue were analyzed using the finite-element analysis software.

RESULTS

1) Stress peaks: the stress peaks of the maximum principal stress, the von Mises stress and the modified von Mises in group A were the largest, except that the stress peak of von Mises stress in group D was slightly lower than that in group C. The stress peaks of the maximum principal stress and the modified von Mises in group C were the lowest. The stress peaks of the maximum principal stress and the modi-fied von Mises stress in group D were lower than those in groups A and B. 2) Stress distribution: compared with group A, the stress distribution of cervical dentin and the area of stress concentration in group C was lower and smaller. In the root dentin, the stress distribution in group C was more uniform than that in group A, and the stress was dispersed to several areas of the root apex. After crown restoration, no significant difference was observed in stress distribution between groups B and D in the root region. The stress distribution state of group B was not significantly different from that of group A. No significant difference was observed in the stress distribution state between groups D and C.

CONCLUSIONS

1) From the perspective of biomechanics, the minimally invasive access was adopted for the maxillary central incisor. 2) Full crown restoration is recommended after traditional access cavity preparation. No obvious advantage is observed in stress analysis for minimally invasive endodontics-restored full-ceramic crown.

Implant-to-bone force transmission: a pilot study for in vivo strain gauge measurement technique

The experimental determination of local bone deformations due to implant loading would allow for a better understanding of the biomechanical behavior of the bone-implant-prosthesis system as well as the influence of uneven force distribution on the onset of implant complications. The present study aimed at describing an innovative in vivo strain gauge measurement technique to evaluate implant-to-bone force transmission, assessing whether and how oral implants can transfer occlusal forces through maxillary bones. In vivo force measurements were performed in the maxillary premolar region of a male patient who had previously received a successful osseointegrated titanium implant. Three linear mini-strain gauges were bonded onto three different buccal cortical bone locations (i.e. coronal, middle, apical) and connected to strain measuring hardware and software. A customized screw-retained abutment was manufactured to allow for vertical and horizontal loading tests. As to the vertical load test, the patient was instructed to bite on a load cell applying his maximum occlusal force for 20 s and then recovering for 10 s to restore the bone unstrained state; the test was repeated 20 times consecutively. As regards the horizontal load test, the implant was subjected to a total of 20 load applications with force intensities of 5 and 10 kg. During the tests, the recorded signals were plotted in real time on a graph as a function of time by means of a strain analysis software. The described strain gauge measurement technique proved to be effective in recording the forces transmitted from osseointegrated implants to the cortical bone. Horizontal loads caused higher deformations of cortical bone than vertical biting forces; in both situations, the deformation induced by the force transferred from the implant to the bone progressively decreased from the coronal to the apical third of the alveolar ridge. At approximately 9 mm from the implant neck, the effect of occlusal force transmission through osseointegrated titanium implants was negligible if compared to the apical region.