Ultrasonic vs Radiographic Measurement of Gingival Biotype. A Novel Method

This clinical study consists on taking 2 different records of the upper and lower incisors area : 1) a perpendicular x-ray and 2) an ultrasonic measurement of gingival thickness on the labial plate. Both measurements are used in order to measure gingival and bone thickness. The aim was to verify the reliability of the tissue measurements of an ultrasonic technique compared with the radiographic technique and to verify whether the biotype has correlation between the maxillary and mandibular biotype in the same patient.

The examination of the patients included: One color photograph of the upper and lower incisors complex with the periodontal probe introduced on the gingival sulcus Gingival thickness of the most protruded upper and lower incisors was measured with the biometric scanner PIROP. A lip expander was placed and clorhexidine gel was applied on top of the ultrasonic head for better wave conduction. Measurements were taken 10 times at the same point and a mean measurement was obtained. A tangential radiograph was taken on each patient perpendicular to the axis of the crown of the central upper and lower incisors with a periapical film holding system, and a metal strip (5mm x 1mm x 0,1mm) placed labial to the keratinized gingiva following the inclination of the incisor. A lip expander was used to keep the lips from touching the metal strip. Air was blown over the attached gingiva before placing the metal strip. The metal strip was placed along the long axis of the most protruded lower incisor crown. All patients were evaluated and categorized in one of three possible categories: A1 (7 patients, 23,3%), A2 (12 patients, 40%), and B (11 patients, 36,7%). The patients were assigned into each category by two examiners, according to the visual and clinical aspect of the keratinized gingiva in the lower incisors. Group A1 and A2 both had thin keratinized gingiva and differed in width (group A1 comprised values ≤2mm, and group A2 had width values >2mm of keratinized gingiva). Group B comprised thick and wide keratinized gingiva. Width of gingiva was measured with a periodontal probe. Thickness of gingiva was assessed by probe transparency, where the examiner determined whether the periodontal probe was visible through the marginal soft tissue. Radiographic measurements Radiographs were scanned at a 1:1 scale. Scanned images were saved in JPEG format. Millimetric measurements were made using the Adobe Photoshop program to a 0.1mm precision. Four measurements were taken on each radiograph: Gingival thickness on the upper incisor Bone thickness on the upper incisor Gingival thickness on the lower incisor Bone thickness on the lower incisor Gingival thickness was measured on the radiographs to compare it with the measurements taken with the biometric scanner. This was a founded and a reliable method to validate the use of the scanner. A master file was created and the data were statistically analyzed using a statistical software package. Size of the sample was obtained with the correlation of lower gingiva and thickness of lower gingiva. The result was 26 calculated with the correlation coefficient 0,587. A 20% tax of follow-up loss was estimated. Intraexaminer reliability was determined using intraclass correlation coefficient (ICC) with a positive confidence interval at 95% (IC 95%). An ICC was used to compare the valid method for group classification between visual and probe transparency methods. The data were subjected to 95% confidence interval for the mean of all variables. The strength of correlation was determined by a P value <0.05, which was considered statistically significant.

A Periodontal probe was used to differentiate between thick and thin biotypes and patients were classified into 3 possible categories of Gingival Biotype (A1, A2 and B) according to Müller & Eger (https://doi.org/10.1034/j.1600-051x.2000.027009621.x). On each group two measurements were taken on the most protruded lower and upper central incisor: 1/ a tangential radiographic film and 2/ an ultrasonic probe measurement with the PIROP Biometric scanner (G-scan) form Echoson

apply the head of the ultrasonic probe on the keratinized tissue of the most protruded upper and lower central incisor in order to measure tissue thickness.

Classify all patients into one of the three established categories (A1, A2, B) with the aid of a periodontal probe, and compare within the same patient if the biotype of maxilla and mandible is the same or it differs

Classify patients in male or female and measure tissue thickness regardless of the biotype measured with both the radiographic technique and ultrasonic device

establish a possible correlation between maxilla and mandible tissue thickness according to the three possible established categories of biotype measured with radiographic technique and ultrasonic device

Inclusion Criteria: aged 18 years or older, presence of all lower incisors good periodontal health without bone loss or gingival inflammation no dental compensations of skeletal malocclusion crowding of less than 4mm no history of dental or traumatic lesions in lower incisors Exclusion Criteria: gingival inflammation daily smokers patients taking drugs that causes gingival inflammation

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Eghbali A, De Rouck T, De Bruyn H, Cosyn J. The gingival biotype assessed by experienced and inexperienced clinicians. J Clin Periodontol. 2009 Nov;36(11):958-63. doi: 10.1111/j.1600-051X.2009.01479.x. Epub 2009 Oct 6.

Zweers J, Thomas RZ, Slot DE, Weisgold AS, Van der Weijden FG. Characteristics of periodontal biotype, its dimensions, associations and prevalence: a systematic review. J Clin Periodontol. 2014 Oct;41(10):958-71. doi: 10.1111/jcpe.12275. Epub 2014 Aug 27.