Is miniscrew primary stability influenced by bone density?

Mariana Marquezan,Matilde Da Cunha Gonçalves Nojima,Margareth Maria Gomes De Souza,Mônica Tirre De Souza Araújo,Lincoln Issamu Nojima

doi:10.1590/s1806-83242011000500009

Mariana Marquezan, Matilde Da Cunha Gonçalves Nojima + Show 3 more

Open Access

https://doi.org/10.1590/s1806-83242011000500009

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Abstract

Primary stability is absence of mobility in the bone bed after mini-implant placement and depends on bone quality among other factors. Bone quality is a subjective term frequently considered as bone density. The aim of this preliminary study was to evaluate bone density in two bovine pelvic regions and verify the primary stability of miniscrews inserted into them. Forty bone blocks were extracted from bovine pelvic bones, 20 from iliac and 20 from pubic bone, all of them containing cortical bone about 1 mm thick. Half of the sections extracted from each bone were designated for histological evaluation of bone density (trabecular bone area - TBA) and the other half for bone mineral density (BMD) evaluation by means of central dual-energy X-ray absorptiometry (DEXA). Then, twenty self-drilling miniscrews (INP®, São Paulo, Brazil) 1.4 mm in diameter and 6 mm long were inserted into the bone blocks used for BMD evaluation. Peak implant insertion torque (IT) and pull-out strength (PS) were used for primary stability evaluation. It was found that iliac and pubic bones present different bone densities, iliac bone being less dense considering BMD and TBA values (P > 0.05). However, the miniscrew primary stability was not different when varying the bone type (P < 0.05). IT and PS were not influenced by these differences in bone density when cortical thickness was about 1 mm thick.

Highlights

Primary stability is absence of mobility in the bone bed after implant or mini-implant placement.[1,2] It is achieved by mechanical contact between the miniscrew surface and bone[3] and depends on the characteristics of devices[4,5], insertion technique[4] and bone quality and quantity of the receptor site.[4,6,7,8]The primary stability plays an important role in the successful secondary stability of miniscrews, since lack of immediate stability can lead to progressive mobility of the device and its subsequent loss.[9]
Statistical difference was observed for the variables that evaluated bone quality: bone mineral density (BMD) – P = 0.000; trabecular bone area (TBA) – P = 0.002
During exploration of this bone, it was observed that some characteristics such as color, texture and drill resistance differed in its various regions

Summary

Introduction

Primary stability is absence of mobility in the bone bed after implant or mini-implant placement.[1,2] It is achieved by mechanical contact between the miniscrew surface and bone[3] and depends on the characteristics of devices[4,5], insertion technique[4] and bone quality and quantity of the receptor site.[4,6,7,8]The primary stability plays an important role in the successful secondary stability of miniscrews, since lack of immediate stability can lead to progressive mobility of the device and its subsequent loss.[9]. Primary stability is absence of mobility in the bone bed after implant or mini-implant placement.[1,2] It is achieved by mechanical contact between the miniscrew surface and bone[3] and depends on the characteristics of devices[4,5], insertion technique[4] and bone quality and quantity of the receptor site.[4,6,7,8]. There is still no gold standard to assess the primary stability of miniscrews.[13]

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