Evaluation of the C-lingual Retractor and the Conventional Lingual Orthodontic Brackets in Terms of Speech Performance and Oral Discomfort: A Randomized Controlled Trial

Abstract

Background The C-lingual retractor (CR) is an alternative lingual technique to retract anterior teeth with minimum torque expression loss. Although the effects of lingual braces upon speech and oral comfort have been studied previously, there is no published data about the C-lingual retractor in this aspect. The aims of this trial were to compare (1) speech performance based on objective acoustic analysis and (2) levels of oral impairment between C-lingual retractor and conventional lingual brackets (LBs). Materials and methods A parallel-group randomized controlled trial was conducted on patients with class II division 1 malocclusion who sought orthodontic treatment at the Department of Orthodontics, Hama University Dental School. Thirty-six patients who met inclusion criteria were randomly selected and divided into two groups. Eighteen patients in the C-lingual retractor group (CR group) were treated with a C-lingual retractor, whereas eighteen patients in the lingual brackets group (LB group) were treated with conventional lingual brackets (Stealth H, American Orthodontics, Sheboygan, WI, USA). Fricative /s/ sound spectrograms were analyzed before (T0), immediately after (T1), one month after (T2), and three months after appliance placement (T3). The levels of oral discomfort were assessed using standardized questionnaires to evaluate speech, irritation, chewing difficulties, and other oral impacts. Results At all assessment times, the C-lingual retractor caused significant deteriorations in articulation, whereas in the lingual brackets group these deteriorations were statistically significant at T1 and T2 (P<0.001) but not significant at T3 (P=0.073). No intergroup differences were detected. Questionnaire analysis revealed that irritation of the tongue was significantly higher in the lingual brackets group after 24 hours of appliances' placement (P=0.007), whereas speech and mastication problems were insignificantly higher in the C-lingual retractor group. Conclusions The findings indicate that the C-lingual retractor has insignificantly a little more interaction with sound production than lingual brackets. Although the levels of oral impacts were almost similar among both groups, more tongue irritation was observed in the lingual brackets group. However, the oral discomfort decreased over the observation period in both groups.

Keywords: auditive analysis; c-lingual retractor; lingual brackets; oral discomfort; speech.

Figure 1. CONSORT flow diagram of patient recruitment, assignment, and follow-up.

CONSORT: Consolidated Standards of Reporting Trials. Mp-SN: mandibular plane-anterior cranial base angle.

Figure 2. The appliances used in the current trial (A) the C-lingual retractor appliance and (B) the lingual brackets appliance.

Figure 3. Spectrogram of the Arabic word "Hassan".