Nonsurgical Maxillary Expansion in Adults: Report on Clinical Cases Using the Hyrax Expander

Background: Maxillary expansion in adults is object of intense controversy and is still considered an unreliable procedure within the orthodontic community. Therefore, the surgically assisted rapid maxillary expansion is still considered the elective treatment nowadays. The aim of this study is to evaluate the efficacy of a nonsurgical maxillary expansion treatment in adult patients with unilateral or bilateral crossbites and to assess the occurrence of related complications, such as pain and tissue swelling, tipping of the posterior teeth and gingival recessions.

Methods: Maxillary expansion using a Hyrax appliance on the upper first premolars and first molars was performed in 29 patients ranged between 18 and 32 years, mean age of 22±4 years. The sample included 13 patients with unilateral crossbite and 16 with bilateral crossbite. The statistical analysis was carried out using the SPSS Statistics version 23.0. An analysis of the paired data obtained on dental casts before and after treatment was performed using the Student's t-test.

Results: The posterior crossbite was fully corrected in all patients. The procedure was well tolerated, and pain, swelling or discomfort was not significant. Statistically significant differences were found between the interdental widths for all pairs, with a P<0.001 for all of them, except in the measurements of canines, in which P=0.001. Measurements of clinical crown height at the beginning (T0) and at the end (T1) of treatment were performed for the same teeth. An increase of the clinical crown height between 0.14 and 0.44 mm was found for premolars and molars.

Conclusions: The results indicate that nonsurgical maxillary expansion in adult patients is an efficient method for correcting transverse deficiency in the maxillary arch. Similarly, the level of complications during treatment was not clinically significant, thus this procedure may be considered a safe treatment.