Three-Dimensional Finite Element Investigation into Effects of Implant Thread Design and Loading Rate on Stress Distribution in Dental Implants and Anisotropic Bone

Variations in the implant thread shape and occlusal load behavior may result in significant changes in the biological and mechanical properties of dental implants and surrounding bone tissue. Most previous studies consider a single implant thread design, an isotropic bone structure, and a static occlusal load. However, the effects of different thread designs, bone material properties, and loading conditions are important concerns in clinical practice. Accordingly, the present study performs Finite Element Analysis (FEA) simulations to investigate the static, quasi-static and dynamic response of the implant and implanted bone material under various thread designs and occlusal loading directions (buccal-lingual, mesiodistal and apical). The simulations focus specifically on the von Mises stress, displacement, shear stress, compressive stress, and tensile stress within the implant and the surrounding bone. The results show that the thread design and occlusal loading rate have a significant effect on the stress distribution and deformation of the implant and bone structure during clinical applications. Overall, the results provide a useful insight into the design of enhanced dental implants for an improved load transfer efficiency and success rate.

Three-Dimensional Finite Element Investigation Into Effects of Implant Thread Design and Loading Rate on Stress Distribution in Dental Implants and Anisotropic Bone

Variations in the implant thread shape and occlusal load behavior may result in significant changes in the biological and mechanical properties of dental implants and surrounding bone tissue. Most previous studies consider a single implant thread design, an isotropic bone structure, and a static occlusal load. However, the effects of different thread designs, bone material properties, and loading conditions are important concerns in clinical practice. Accordingly, the present study performs Finite Element Analysis (FEA) simulations to investigate the static, quasi-static and dynamic response of the implant and implanted bone material under various thread designs and occlusal loading directions (buccal-lingual, mesiodistal and apical). The simulations focus specifically on the von Mises stress, displacement, shear stress, compressive stress and tensile stress within the implant and the surrounding bone. The results show that the thread design and occlusal loading rate have a significant effect on the stress distribution and deformation of the implant and bone structure during clinical applications. Overall, the results provide a useful insight into the design of enhanced dental implants for an improved load transfer efficiency and success rate.

Consequences of Peri-Implant Bone Loss in the Occlusal Load Transfer to the Supporting Bone in terms of Magnitude of Stress, Strain, and Stress Distribution: A Finite Element Analysis

Background and Objective. Marginal bone loss around dental implants is one of the most prevalent complication, and its biomechanical impact may be critical for treatment prognosis. The objective of this study was to evaluate the influence of marginal bone loss around dental implants in the occlusal load transfer to the bone in terms of magnitude of stress and strain and distribution of such transferred stress. Methods. Three models of a single internal connection bone level-type implant inserted into a posterior mandible bone section were constructed using a 3D finite element software: one control model without marginal bone loss and two test models, both with a circumferential peri-implant bone defect, one with a 3 mm high defect and the other one 6 mm high. A 150 N static load was tested on the central fossa at 6° relative to the axial axis of the implant. Results. The results showed differences in the magnitude of strain and stress transferred to the bone between models, being the higher strain found in the trabecular bone around the implant with greater marginal bone loss. Stress distribution differed between models, being concentrated at the cortical bone in the control model and at the trabecular bone in the test models. Conclusion. Marginal bone loss around dental implants under occlusal loading influences the magnitude and distribution of the stress transferred and the deformation of peri-implant bone, being higher as the bone loss increases.

GUIDED ENDODONTIC ACCESS

We have come a long way in dentistry from “extension for prevention” to “prevention of extension”. Asimilar approach in endodontics is going to change the future of dental practice with Minimal Invasive Endodontics (MIE). MIE mainly includes preservation of structural integrity of tooth, alternate access cavity designs, guided endodontic access, modern burs, cleaning and shaping, 3D irrigation and disinfection, magnication aids like loupes and dental operating microscope. Survival of an endodontically treated tooth depends mainly on its remaining structural integrity after access preparation. The concept of Conservative endodontic cavities (CEC) was introduced to preserve the pericervical dentin (PCD), which is crucial to transfer the occlusal load to the root. In traditional endodontic cavities (TEC) much of PCD is lost which reduces the fracture resistance of tooth. Guided endodontic access was introduced as an attempt to preserve the PCD. It ensures predictable outcome without any procedural errors. The present paper attempts to narratively summarize the scope of Guided endodontic access in dental practice and explain its benets to the practitioners compared with conventional technique

AMOUNT OF BONE LOSS AND DIGITAL OCCLUSAL ANALYSIS OF DIFFERENT ATTACHMENT DESIGNS IN BILATERAL DISTAL EXTENSION PARTIAL DENTURE CASES

Background: OT unilateral extra-coronal attachmentconsidered as one of the best choices for distal extension partially edentulous cases. Aim: Comparing OT unilateral extra-coronal attachment with modified OT unilateral extra-coronal attachment RPDs with bracing arm regardingamount of bone loss and occlusal load (using T-scan system). Methods: Ten patients have missing bilateral mandibular molars teeth were treated according to split-mouth design using protocol A (OT unilateral extra-coronal attachment) and protocol B (modified OT unilateral extra-coronal attachment with a bracing arm). Amount of bone loss was evaluated radiographically at time of denture insertion, 3months, 6month, 9months, 12month and 18 months after denture delivery to measure the bone height changes. Also, occlusal load was evaluated using T-scanner (Digital occlusal analysis). Results: Regarding bone loss: Protocol B was significantly lower than protocol A after 6 and 12 months, while in occlusal load analysis Protocol B was insignificantly lower than protocol A. Conclusion: Less vertical bone height resorption and less occlusal forces in bracing side (OT unilateral extra-coronal attachment RPDs with a bracing arm) when compared with the non-bracing side.

ASSESSMENT OF THE INFLUENCE OF THE ORAL ENVIRONMENT ON THE STRENGTH OF ENDODONTIC CROWNS MADE OF HYBRID CERAMICS IN THE LABORATORY

A topical issue in dentistry is the problem of restoring teeth after endodontic treatment. There are many materials available to restore them. However, each of them has its own negative properties. The purpose of this work was to determine the degree of influence of the oral environment on the strength characteristics of endocrowns made of hybrid ceramics. 30 samples from hybrid ceramics were examined. One of the groups was confirmed by thermal Cycling, and the other was not. Further, both groups on the Instron-5982 device were subjected to vertical compression load before the destruction began. According to the results of this study, it can be noted that endocorns made of hybrid ceramics perfectly distribute the occlusal load and have good elasticity, but thermal Cycling has a negative impact on the strength characteristics of this material.

Influence of Tooth Factors and Procedural Errors on the Incidence and Severity of Post-Endodontic Pain: A Prospective Clinical Study

The objective of this prospective study was to assess tooth-related factors that play a role in the incidence of postoperative pain (PP) and determining if procedural errors influence PP occurrence. A total of 442 patients referred for root canal treatment met the inclusion criteria and were included in this prospective study. The same protocol was used in all root canal treatments. Patient, tooth, treatment related factors and the occurrence of procedural errors were registered. Incidence and intensity of PP was assessed at 24 and 48 h by telephonic interview and in person seven and 15 days after treatment. A logistic and ordinal regression analysis was used to assess the role of patient, tooth and treatment related factors in the incidence and intensity of PP, respectively. Preoperative and intraoperative factors differently affected the incidence of PP at the different time intervals. The presence of procedural errors did not significantly influence PP occurrence. The presence of preoperative pain and the need of additional anesthesia during treatment were associated with higher incidence of PP 24 and 48 h after treatment; the extent of apical enlargement played a significant role in the presence of PP after seven days of treatment; and the excessive occlusal load induced by the absence of a contralateral tooth was the only factor related to the maintenance of PP up to 15 days. In conclusion, the presence of preoperative pain, the need of additional anesthesia during treatment, the extent of apical enlargement and the excessive occlusal load induced by the absence of a contralateral tooth were related to a higher incidence of PP.

ASSESSMENT OF THE PARAMETERS OF THE INTEROCCLUSION RELATIONSHIP IN THE PROCESS OF MESIALIZATION OF THE LOWER MOLARS WITH THE USE OF T-SCAN

The aim of the study. Conduct a digital analysis of the distribution of relative force occlusal load in the area of the second permanent mandibular molars before and after their mesialization. Research methods. In order to evaluate the distribution of inter-occlusal force load in the process of mesialization of molars on the mandible, two clinical study groups were formed. The first group consisted of 32 persons (18 women / 56.25% and 14 men / 43.75%) aged from 18 to 25 years, who had orthodontic treatment using braces and mini-implants. The second group included 30 people (19 women / 63.33% and 11 men / 36.67%), orthodontic treatment was performed using a brace system without additional intraosseous support on the mini-implants. T-scan apparatus investigated the distribution of relative force occlusal load in the area of the second permanent mandibular molars before and after orthodontic intervention. Results of the study. The use of the T-scan apparatus is an accurate and informative tool for analyzing the distribution of functional occlusal force load within the dentition. During the analysis of the parameters of the chewing load in the area of the second permanent molars on the mandible before orthodontic treatment, an increase of this index was found in almost all patients of both study groups. In the first group in 4 (12.5%) persons the maximum relative occlusive force load in the area of the second permanent molars on the mandible was 10–20%, which is the range of the norm; in 15 (46.9%) cases this indicator was 20–30. %, in 10 (31.2%) patients had 30-40%, and in 3 (9.4%) exceeded 40%. In the second group, the parameters of the relative force occlusal load in the area of the second permanent molar on the mandible were as follows: in 5 (16.7%) persons in the range of 10-20%, in 13 (43.3%) persons - 20-30%, in 10 (33.3%) patients - 30-40% and in 2 (6.7%) patients more than 40%. After treatment, normalization of the relative occlusal force load was observed in the area of the second permanent molars on the lower jaw in the majority of patients of both study groups. In particular, in the first group in 21 (65.6%) persons the parameters of occlusal load were in the range of 10–20%, in 11 (34.4%) persons were 20–30%. In the second study group, 17 (56.7) patients observed parameters of the occlusal load on the second molar in the range of 10-20%, in 12 (40%) persons - 20-30% and in one (3.3%) patient 30-40%. In addition, moving molars involves changing the usual occlusal ratios associated with the non-identity factor in the shape and size of the first and second molars. At the same time, occlusal contacts on all other teeth are altered due to their alignment with the orthodontic equipment and the appearance of new contact points that did not interact before the start of treatment. Conclusions. The analysis of the distribution of the relative occlusal load in the area of the second permanent molars on the lower jaw with the help of T-scan after orthodontic treatment revealed the normalization of this indicator in the majority of patients in both study groups. Specifically, in the first group, 21 (65.6%) subjects had parameters of relative occlusal load within the range of 10–20%, and in 11 (34.4%) individuals were 20–30%. In the second study group, 17 (56.7%) patients were in the range of 10–20%, 12 (40%) patients - 20–30% and one (3.3%) patients 30–40%. The data obtained in both the first and second study groups indicate the need to perform procedures of grinding after orthodontic intervention to achieve appropriate occlusive normalization, the volume of which in each clinical situation is determined individually under the control of the T-scan apparatus.

Study of the stress–strain state of spongy bone around an implant under occlusal load

The article studies the stress–strain state of the spongy bone of an implanted jaw. A spongy bone can be considered as a multiporous area with its fissures and pores as the most visible components of a double-porous system. The work studies the stress–strain state of the spongy jaw-bone near the implant, which is under occlusal load. A mathematical model of the problem is the contact problem of the theory of elasticity between the implant and the jaw-bone. The problem is solved by using the boundary element methods, which are based on the solutions of Flamant (BEMF) and Boussinesq’s (BEMB) problems. The cases of various lengths of an implant diameter are considered. Stress contours (isolines) in the jaw-bone are drawn and the results obtained by BEMF and BEMB for the different-diameter implants are compared.