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Int Poster J Dent Oral Med 10 (2008), No. 4     15. Dec. 2008

Int Poster J Dent Oral Med 2008, Vol 10 No 04, Poster 431

Biomechanical evaluation of miniscrew implants in vitro

Selectively demineralized bone technique

Language: English
 

Authors:
Assoc. Prof. Boonsiva Suzuki, DDS. PhD, Dr. Eduardo Yugo Suzuki, DDS. PhD, Dr. Kanchana Doungsaard, DDS, Dr. Prakarn Prasoothavee, DDS, Dr. Weeranuch Thong-ngarm, DDS, Dr. Sorapong Chuensombat, DDS,
Department of Orthodontics, Faculty of Dentistry
Dr. Apirum Janhom, DDS, MS, PhD,
Department of Radiology, Faculty of Dentistry
Chiang Mai University, Thailand

Date/Event/Venue:
December 14th-16th, 2007
The 6th Asian Implant Orthodontic Conference (AIOC)
Taichung, Taiwan
 

Poster Award
Outstanding Poster Award - 1st place

Introduction

Bone quality plays an important role in the success of orthodontic miniscrew implants. (1, 2) The mechanical properties of bone are highly related to the mineral content, which varies widely according to function and histology. However, in vitro methods for evaluating biomechanical properties of miniscrew implants have not been reported.
 

Objectives

The aim of this study was to assess the biomechanical performance of miniscrew implants using bone samples which were demineralized by timed chemical immersion to alter the mineral content. (3)
 

Material and Methods

Sections of fresh rib bones from adult pigs were selectively demineralized by timed immersion in 1 % ethylenediamine-tetraacetic (EDTA). Specimens were removed from the solution after 0(control), 6, 10, 16, 30 and 50 days and embedded in acrylic blocks (Figs. 1-4). Quantification of bone density was performed using radiographic images processed with Photoshop software (Figs. 5 and 6). Fifty miniscrew implants, 8 mm long and 1.5 mm in diameter (BMK - Biomaterials, Korea) were inserted. Maximum insertion torque was recorded with a toque gauge. Pullout strength was tested using an Instron Universal testing machine (Figs. 7 and 8). Statistical analysis was performed using the Kruskal-Wallis Test and Spearman correlation coefficients.

Fig. 1: Diagram of the selectively bone demineralization technique. Bone samples were demineralized by timed chemical immersion to alter the mineral content. Fig. 2: Sections of fresh rib bones from adult pigs were selectively demineralized by timed immersion in 1 % EDTA.
Figs. 3 and 4: Sections of fresh rib bones from adult pigs were selectively demineralized by timed immersion in 1 % EDTA.
 
Fig. 5: Radiographic images of each bone sample were obtained
 
Fig. 6: Quantification of bone density was performed using radiographic images processed with Photoshop software
 
Fig. 7: Maximum insertion torque and pullout strength were assessed
 
 
Fig. 8: Maximum insertion torque and pullout strength were assessed
 
 

Results

The selectively bone demineralization was successfully performed (Figs. 9 and 10). There was a systematic decrease in bone density that was followed by a significant decrease in the biomechanical properties of the miniscrews. High correlation (r = 0.91) was observed between maximum insertion torque and maximum pullout strength (Figs. 11-13).

Figs. 9 and 10: The selectively bone demineralization was successfully obtained
Fig. 11: Bone density values Fig. 12: Maximum insertion torque values
 
Fig. 13: Maximum insertion torque values
 
 

Conclusions

The biomechanical properties of miniscrew implants can be evaluated in vitro using bones obtained from a single species prepared with the selectively demineralized bone technique. The proposed method can be used to facilitate comparison between different miniscrew implant systems, avoiding the inaccuracy observed in conventional methods.
 

Acknowledgements

The authors acknowledge the assistance of Dr. M. Kevin O Carroll, Professor Emeritus of the University of Mississippi School of Dentistry, USA, and Faculty Consultant, Chiang Mai University Faculty of Dentistry, Thailand, in the preparation of the manuscript.

Part of this study was supported by the Thailand Research Fund, Grant No. MRG5080347.
 

Literature

  1. Huja SS, Litsky AS, Beck FM, Johnson KA, Larsen PE: Pull-out strength of monocortical screw placed in the maxillae and mandible of dogs. Am J Orthod Dentofacial Orthop 127: 307-313, 2005.
  2. Accuracy of miniscrew implant placement with a 3-dimensional surgical guide.J Oral Maxillofac Surg. 2008 Jun;66(6):1245-52.
  3. Broz JJ, Simske S, Greenberg AR: Material and compositional properties of selectively demineralized cortical bone. J Biomech 28: 1357-1368,1995.
     

This Poster was submitted by Boonsiva Suzuki.
 

Correspondence address:
Dr. Eduardo Yugo Suzuki
Chiangmai University
Department of Orthodontics, Faculty of Dentistry
Suthep Road
Amphur Muang 50200
Thailand