Relation between insertion torque and tactile, visual, and rescaled gray value measures of bone quality: a cross-sectional clinical study with short implants

Abstract

Background: This study assessed the relationship between insertion torque and bone quality evaluated during surgery and in preoperative computed tomographic (CT) images analyzed either visually or by rescaled mean gray values (MGVs). The study also tested the correlation between the clinical and radiographic measures of bone quality.

Methods: The consecutive sample was composed of 45 short implants (4.1 × 6 mm) placed in the posterior region of 20 patients. Intra-surgical tactile bone quality, based on the classification of bone types by Lekholm and Zarb, and insertion torque were recorded during the implant placement. Visual bone quality and normalized MGV were assessed in standardized axial, coronal, and sagittal sections of preoperative CT images. Data were analyzed by ANOVA and Spearman correlation (alpha = 0.05).

Results: Insertion torque was associated with all assessment methods of bone quality (tactile, CT visual, MGV). A moderate correlation was found among all methods of bone quality, except for CT visual assessment and tactile evaluation. MGVs varied as a function of arch, dental region, insertion torque, and bone types.

Conclusions: The results suggest that bone quality measures affect primary stability as recorded by insertion torque, and the assessment methods are consistently related.

Keywords: Bone quality; Insertion torque; Primary stability; Short implants.

Conflict of interest statement

Ethics approval and consent to participate

This study was conducted in accordance with the tenets of the Declaration of Helsinki, and all procedures involving human subjects were approved by the ethics committee of the Pontifical Catholic University of Rio Grande do Sul/UBEA (ethical approval letter OF.CEP-772/10; research protocol CEP 10/05074).

Consent for publication

Written informed consent was obtained from all study participants.

Competing interests

Diego Fernandes Triches, Fernando Rizzo Alonso, Luis André Mezzomo, Danilo Renato Schneider, Eduardo Aydos Villarinho, Maria Ivete Rockenbach, Eduardo Rolim Teixeira, and Rosemary Sadami Shinkai declare that they have no competing interests.

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Figures

Fig. 1

Clinical case of a short implant (4.1 × 6 mm) placed in the region of the left maxillary first molar. a Implant installed. b Insertion torque measurement using the manual torque wrench. c Implant with healing cap and flap suture. d Immediate periapical radiograph after surgery

Fig. 2

Preoperative CT image showing the site for the definition of the ROI (simulated area delimited by a yellow dashed line for illustration purpose) in the axial (a), coronal (b), and sagittal (6 × 6 mm) (c) sections

Fig. 3

One possible missing category (depicted as “X”) would be a bone type with thick cortical layer and sparse trabecular bone, which would have intermediate characteristics and behavior between the types with thick (2) or thin (3) cortical bones