Biomechanics of Immediate Postextraction Implant Osseointegration

Abstract

The aim of this study was to gain insights into the biology and mechanics of immediate postextraction implant osseointegration. To mimic clinical practice, murine first molar extraction was followed by osteotomy site preparation, specifically in the palatal root socket. The osteotomy was positioned such that it removed periodontal ligament (PDL) only on the palatal aspect of the socket, leaving the buccal aspect undisturbed. This strategy created 2 distinct peri-implant environments: on the palatal aspect, the implant was in direct contact with bone, while on the buccal aspect, a PDL-filled gap existed between the implant and bone. Finite element modeling showed high strains on the palatal aspect, where bone was compressed by the implant. Osteocyte death and bone resorption predominated on the palatal aspect, leading to the loss of peri-implant bone. On the buccal aspect, where finite element modeling revealed low strains, there was minimal osteocyte death and robust peri-implant bone formation. Initially, the buccal aspect was filled with PDL remnants, which we found directly provided Wnt-responsive cells that were responsible for new bone formation and osseointegration. On the palatal aspect, which was devoid of PDL and Wnt-responsive cells, adding exogenous liposomal WNT3A created an osteogenic environment for rapid peri-implant bone formation. Thus, we conclude that low strain and high Wnt signaling favor osseointegration of immediate postextraction implants. The PDL harbors Wnt-responsive cells that are inherently osteogenic, and if the PDL tissue is healthy, it is reasonable to preserve this tissue during immediate implant placement.

Mechanoadaptive Responses in the Periodontium Are Coordinated by Wnt

“…We used Axin2 CreERT2/+ ; R26R mTmG/+ mice (Yuan, Pei, Zhao, Li, et al 2018) in which Wnt-responsive stem/progenitor cells and their descendants are labeled with green fluorescent protein (GFP; Fig. 4A) to characterize their distribution in the PDL of mice with intact dentition ( Appendix Fig.…”

A novel cryo-embedding method for in-depth analysis of craniofacial mini pig bone specimens

“…Consequently, most cryo-processed hard tissues from large animals are first decalcified 26 . Cryo-processing does work well for small hard tissue samples e.g., from rodents [27][28][29][30] but here our interest was in hard tissues from large animal studies that are typically performed for preclinical safety/ toxicity testing of drugs and devices intended for use in humans.…”

Combination of biomechanical evaluation and accurate placement of dental implants: a new concept of virtual surgery in maxillary and mandibular functional reconstruction

“…[16][17][18][19] In case of maxillary or mandibular functional reconstructions with placement of dental implants, greater stresses are expected during mastication than in reconstructions of normal maxillofacial bone, although bite and chewing forces will be reduced postoperatively. [20][21][22] The main contribution of this paper is the design of a precise, individual, virtual surgical plan with favourable biomechanical properties, and the implementation of the plan for maxillary and mandibular reconstructions.…”