Clinical efficacy of intraoral ultrasonography versus transgingival probing for measurement of gingival thickness in different gingival biotypes: a clinical trial

Abstract

Background: Transgingival probing is conventionally used for gingival thickness (GT) measurement. However, invasiveness is a major drawback of transgingival probing. Thus, researchers have been in search of alternative methods for measurement of GT. This study compared the clinical efficacy of intraoral ultrasonography and transgingival probing for measurement of GT in different biotypes.

Materials and methods: This clinical trial was conducted on 34 patients requiring crown lengthening surgery. GT was measured at 40 points with 2- and 4-mm distances from the free gingival margin (FGM) of anterior and premolar teeth of both jaws in each patient by an intraoral ultrasound probe. For measurement of GT by the transgingival probing method, infiltration anesthesia was induced, and a #25 finger spreader (25 mm) was vertically inserted into the soft tissue until contacting bone. The inserted length was measured by a digital caliper with 0.01 mm accuracy. All measurements were made by an operator with high reliability under the supervision of a radiologist. Data were analyzed by t-test, Power and Effect Size formula, and intraclass correlation coefficient (ICC).

Results: The two methods were significantly different in measurement of GT in both thick and thin biotypes at 2- and 4-mm distances (P < 0.001). The two methods had a significant difference in both the mandible (P < 0.001) and maxilla (P < 0.001) and in both the anterior (P < 0.003) and premolar (P < 0.003) regions. Although the difference was statistically significant in t-tests, the power and effect formula proved it to be clinically insignificant. Also, the ICC of the two methods revealed excellent agreement.

Conclusion: The results showed optimal agreement of ultrasound and transgingival probing for measurement of GT.

Trial registration: The study was approved by the ethics committee of Shahid Beheshti University of Medical Sciences on 2021-12-28 (IR.SBMU.DRC.REC.1400.138) and registered in the Iranian Registry of Clinical Trials on 2022-03-14 (IRCT20211229053566N1).

Keywords: Clinical trial; Gingiva; Intraoral; Thickness; Ultrasonography.

Fig. 1

Positioning of intraoral probe of ultrasound for measurement of gingival thickness

Fig. 2

Real-time images showing the buccal surface of the tooth, cementoenamel junction, and buccal bone covering the root surface in the sagittal plane. In the right side, a hyperechoic area at the top (A-arrow) indicates the clinical tooth crown (buccal surface) on which, the probe is placed. The next hyperechoic line (C-arrow) indicates the buccal cortical plate. The intersection of the above mentioned two hyperechoic lines indicates the cementoenamel junction of the tooth (B-arrow). The entire hypoechoic tissue from the superior image margin (indicating the probe surface on the tooth and gingiva) to the hyperechoic area related to tooth or bone indicates the gingival thickness at the mid-buccal region

Fig. 3

Measuring the gingival thickness (GT) at 4 mm distance from the free gingival margin. Points A and B indicate the gingival margin, and 4 mm distance from the free gingival margin, respectively. As shown, the GT at point B was 0.8 mm

Fig. 4

Marking a point at 2 mm distance from the free gingival margin at the mid-buccal of right central incisor by a periodontal probe and insertion of an endodontic spreader into the gingival tissue at this point for measurement of gingival thickness

Fig. 5

CONSORT flow-diagram of patient selection and allocation