Mechano-adaptive Responses of Alveolar Bone to Implant Hyper-loading in a pre-clinical in vivo model

Effects of tensile and compressive stress on bone resorption and formation parameters surrounding dental implants

This study investigates the effects of tensile and compressive stresses on peri-implant bone remodeling activity. Titanium implants were inserted into the extracted maxillary molar sites of four-week-old male mice and allowed to heal. A sustained load of 0.9 N, inclined at 30° from palatal to buccal, was applied for 30 min daily over 7 days. Non-loaded implants served as a controls. Non-demineralized sections parallel to the occlusal plane were prepared 150 μm below the alveolar crest, and bone morphometry parameters related to bone resorption and formation were measured within a 120 μm-wide peri-implant region, divided into distal, buccal, mesial, and palatal quarters. Stress distribution was calculated using an animal-specific three-dimensional (3D) finite element (FE) model based on microfocus CT data. In the buccal quarter, where compressive stress was statistically higher than in the other quarters, and the mesial quarter, where tensile stress was greater than that in the other quarters, bone remodeling parameters increased significantly upon loading (p < 0.05), aligning with previous in vivo findings that mechanical stress influences bone-related cell activity. However, no significant parameter changes were observed in the distal quarter, where both tensile and compressive stresses were higher than those in the other quarters. This suggested regional suppression of remodeling activity by a simultaneous concentration of tension and compression. These findings offer crucial insights into the preservation and maintenance of the peri-implant bone under mechanical stress from occlusal forces, highlighting the role of stress distribution in bone remodeling.

Biomechanical Basis for Bone Healing and Osseointegration of Implants in Sinus Grafts

A thorough comprehension of the mechanisms controlling new bone formation and implant osseointegration after maxillary sinus floor elevation is crucial for aligning our treatment choices with biological principles and enhancing clinical outcomes. The goal of bone regeneration in sinus lift procedures is to provide a sufficient amount of newly-formed tissue to support implant osseointegration. However, it is still unclear whether there is a minimum quantity of vital bone within the newly-formed tissue required for effective support, though it is generally assumed that vital bone is essential for this process. The source and integration of new bone in maxillary sinus floor elevation procedures remain debated. Most clinical studies suggest a paramount role for sinus floor and bony walls, with a centripetal pattern of new bone formation, while conflicting reports exist regarding the osteogenic role of the Schneiderian membrane. The influence of mechanical input on peri-implant bone formation, mineralization, and maturation is significant, with bone remodeling regulated by mechanical strains generated during loading. Defining optimal loading for implants, particularly in sinus lift procedures, is challenging, as early loading may damage interfacial tissue, interfering with osteogenesis. Differences in osseointegration dynamics between native and augmented bone may arise from biological and mechanical factors, but also from patient-specific factors which should be evaluated in treatment planning. Factors to consider include sinus anatomy, patient and site-specific regenerative potential, and the selection of graft material that matches the osteogenic and mechanical requirements. Tailored approaches integrating patient-specific considerations and refined implant strategies will enhance predictability and longevity of treatment.

Finite Element Analysis of Functionally Loaded Subperiosteal Implants Evaluated on a Realistic Model Reproducing Severe Atrophic Jaws

Implant-supported prosthetic rehabilitation for patients with severely atrophic jaws is challenging due to complex anatomical considerations and the limitations of conventional augmentation techniques. This study explores the potential of subperiosteal (juxta-osseous) implants as an alternative solution, using finite element analysis (FEA) to evaluate mechanical performance. Realistic jaw models, developed from radiographic data, are utilized to simulate various implant configurations and load scenarios. Results indicate that different screw placements, implant designs, and structural modifications can significantly influence stress distribution and biomechanical behavior. Upper and lower jaw models were assessed under multiple load conditions to determine optimal configurations. Findings suggest that strategic adjustments, such as adding posterior screws or altering implant connections, can enhance load distribution and reduce stress concentration, particularly in critical areas. Tensile loads in critical bone areas near cortical fixing screws exceeded 50 MPa under anterior loading, while configurations with larger load distributions reduced stress on both implant and bone. The study provides evidence-based insights into optimizing subperiosteal implant design to improve stability, longevity, and patient outcomes.

Topography-mediated immunomodulation in osseointegration; Ally or Enemy

Osteoimmunology is at full display during endosseous implant osseointegration. Bone formation, maintenance and resorption at the implant surface is a result of bidirectional and dynamic reciprocal communication between the bone and immune cells that extends beyond the well-defined osteoblast-osteoclast signaling. Implant surface topography informs adherent progenitor and immune cell function and their cross-talk to modulate the process of bone accrual. Integrating titanium surface engineering with the principles of immunology is utilized to harness the power of immune system to improve osseointegration in healthy and diseased microenvironments. This review summarizes current information regarding immune cell-titanium implant surface interactions and places these events in the context of surface-mediated immunomodulation and bone regeneration. A mechanistic approach is directed in demonstrating the central role of osteoimmunology in the process of osseointegration and exploring how regulation of immune cell function at the implant-bone interface may be used in future control of clinical therapies. The process of peri-implant bone loss is also informed by immunomodulation at the implant surface. How surface topography is exploited to prevent osteoclastogenesis is considered herein with respect to peri-implant inflammation, osteoclastic precursor-surface interactions, and the upstream/downstream effects of surface topography on immune and progenitor cell function.

Effects of masticatory loading on bone remodeling around teeth vs. implants: insights from a preclinical model

OBJECTIVES

Teeth connect to bone via a periodontal ligament whereas implants connect to bone directly. Consequently, masticatory loads are distributed differently to periodontal versus peri-implant bone. Our objective was to determine how masticatory loading of an implant versus a tooth affected peri-implant versus periodontal bone remodeling. Our hypothesis was that strains produced by functional loading of an implant would be elevated compared to the strains around teeth, and that this would stimulate a greater degree of bone turnover around implants versus in periodontal bone.

MATERIALS AND METHODS

Sixty skeletally mature mice were divided into two groups. In the Implant group, maxillary first molars (mxM1) were extracted, and after socket healing, titanium alloy implants were positioned sub-occlusally. After osseointegration, implants were exposed, resin crowns were placed, and masticatory loading was initiated. In a Control group the dentition was left intact. Responses of peri-implant and periodontal bone were measured using micro-CT, histology, bone remodeling assays, and quantitative histomorphometry while bone strains were estimated using finite element (FE) analyses.

CONCLUSIONS

When a submerged osseointegrated implant is exposed to masticatory forces peri-implant strains are elevated, and peri-implant bone undergoes significant remodeling that culminates in new bone accrual. The accumulation of new bone functions to reduce both peri-implant strains and bone remodeling activities, equivalent to those observed around the intact dentition.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2020 professional literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to this work to cover this broad topic. Specific subject areas addressed include prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders (TMDs); sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence day-to-day dental treatment decisions with a keen eye on future trends in the profession. With the tremendous volume of dentistry and related literature being published today, this review cannot possibly be comprehensive. The purpose is to update interested readers and provide important resource material for those interested in pursuing greater detail. It remains our intent to assist colleagues in navigating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the dental patients they encounter.

The Bone Buttress Theory: The Effect of the Mechanical Loading of Bone on the Osseointegration of Dental Implants

Simple Summary

The bone, as a vertebrate support tissue, is capable of adapting its structure and function to the mechanical demands resulting from the loads that are produced during the performance of its activity. This regulatory action also occurs during the healing processes of a fracture. The purpose of this study was to determine to what extent a dynamic load was capable of modulating the bone healing response around a titanium implant. The study was carried out on experimental rabbits, to which dental implants were placed in the tibiae and there were two test groups, one in which they did not undergo exercise during healing period and another that ran daily during this process on a treadmill. The trail results showed an improvement in the osseointegration process of the implant in the group in which it was subjected to load. The importance of these results is that it opens the door to a better understanding of the mechanisms that can modulate bone healing, especially around dental implants, supporting implant loading protocols that are based on efficiency.

Abstract

Objectives: To determine the effect of mechanical loading of bone on the stability and histomorphometric variables of the osseointegration of dental implants using an experimental test in an animal model. Materials and Methods: A total of 4 human implants were placed in both tibiae of 10 New Zealand rabbits (n = 40). A 6-week osseointegration was considered, and the rabbits were randomly assigned to two groups: Group A (Test group) included 5 rabbits that ran on a treadmill for 20 min daily during the osseointegration period; Group B (Controls) included the other 5 that were housed conventionally. The monitored variables were related to the primary and secondary stability of the dental implants (implant stability quotient—ISQ), vertical bone growth, bone to implant contact (BIC), area of regenerated bone and the percentage of immature matrix. Results: The results of the study show a greater vertical bone growth (Group A 1.26 ± 0.48 mm, Group B 0.32 ± 0.47 mm, p < 0.001), higher ISQ values (Group A 11.25 ± 6.10 ISQ, 15.73%; Group B 5.80 ± 5.97 ISQ, 7.99%, p = 0.006) and a higher BIC (Group A 19.37%, Group B 23.60%, p = 0.0058) for implants in the test group, with statistically significant differences. A higher percentage of immature bone matrix was observed for implants in the control group (20.68 ± 9.53) than those in the test group (15.38 ± 8.84) (p = 0.108). A larger area of regenerated bone was also observed for the test implants (Group A 280.50 ± 125.40 mm², Group B 228.00 ± 141.40 mm²), but it was not statistically significant (p = 0.121). Conclusions: The mechanical loading of bone improves the stability and the histomorphometric variables of the osseointegration of dental implants.