Biomechanical analysis of alveolar bone stress around implants with different thread designs and pitches in the mandibular molar area

Abstract

Threaded implants have been shown to play an important role in increasing mechanical osseointegration. The aim of this study was to determine bone stress distribution when using different types of implant thread pitches and designs. Five 3D finite element models were constructed to simulate bone stresses induced in implant bodies with two types of thread form: triangular ("Tri" prefix) and trapezoidal ("Trap" prefix). The former had thread pitches of 0.8, 1.2, and 1.6 mm, while the latter had thread pitches of 1.2 and 1.6 mm. A biting load of 143 N was applied vertically and obliquely to the occlusal central fossa of the crown. The main effects of each level of the three factors investigated (loading type, pitch, and thread form) in terms of the stress value were computed for all models. Results indicated that the loading type was the main factor of influence on the peak compressive stress of the alveolar bone. Optimal thread pitch was 1.2 mm for a triangular-thread implant, and a trapezoidal-threaded implant with thread pitch of 1.6 mm had the lowest stress value among trapezoidal-threaded implants. This study concluded that each thread form has its unique optimal thread pitch with regard to lower concentration of bone stress. Clinically, this study suggests that in biomechanical consideration, thread pitch exceeding 0.8 mm is more appropriate for a screwed implant. For clinical cases that require greater bone-implant interface, trapezoidal-threaded implants with thread pitch of 1.6 mm provide greater primary stability and lower concentration of bone stress under different loading directions.

Analysis of the distribution of stress and deformation in single implant-supported prosthetic units in implants of different diameters

“…To validate the numeric models, a comparison was made with the data in the literature. The levels of stress and deformation found in the present study conform with those found in other finite element analyses 19,21,22 . However, some assumptions were adopted in this study: the bone-implant interface was completely in contact, as in a perfect osseo-integration; the cortical and medullary bones were assumed to be linearly elastic -situations that, clinically, are not always true.…”

“…Several authors have suggested that an increase in the diameter favors the biomechanical issue for peri-implant osseous maintenance [14][15][16] . However, there are other studies that disagree with this 11,[17][18][19] .…”

“…Also, the maximum stress is concentrated mainly in the cortical bone, near the implant collar, when a simulation of chewing load is applied. This localized stress corresponds perfectly to the clinical observation of marginal peri-implant bone loss and occurs, invariably, in all implant diameters 19,21 .…”

Dental Implant Macro‐Design Features Can Impact the Dynamics of Osseointegration

“…In order to improve the osseointegration of titanium implants, several designs were generated throughout the past 20 years. 5,6 Besides modifications in implant surface structure, the implant design itself has been the target of variations in both its macro-and microproperties. The former was the primary variable of the present study, and two implant types displaying a different macro-design were considered.…”

Numerical Study of the Effect of Rigid and Dynamic Posterior Attachment Systems on Stress Reduction in Cortical and Spongy Bones of the Lumbar Segments L4-L5

“…The material properties of the INT model are listed in Table 1 and were chosen from previous studies [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. All seven ligaments were simulated by ten node link elements with resistance tension only, and they were arranged in the anatomical direction given by the text book [54]; the cross-sectional area of each ligament was obtained from previous studies [47,[52][53][54].…”