Three-dimensional CBCT Analysis of Root Volume Changes Following Tooth-bone and Bone-borne Maxillary Expansion: A Pilot Study.

Summary

External root resorption (ERR) is an undesired side effect observed after rapid maxillary expansion (RME). This study aimed to investigate changes in the root volume of maxillary permanent first molars after RME using tooth-borne and bone-borne devices with cone-beam computed tomography (CBCT) software analysis.

The study included 21 patients (mean age 11.8 years ±0.79 years) with skeletal transverse maxillary deficiency, randomly allocated into three groups according to the type of expansion device: tooth-borne Hyrax (TB), bone-borne 4-miniscrew (BB4) and bone-borne 2-miniscrew (BB2). The same expansion screw and activation protocol were applied in all groups. A CBCT was carried out before treatment (T0) and after treatment at a 6-month follow-up (T1). The volumetric assessment of maxillary permanent first molars was performed using digital software, evaluating the mean root volume changes (mm3 and %) between T0 and T1 in each group (TB, BB4, BB2). The Wilcoxon test was used for intra-group comparisons and the Kruskal-Wallis test was used for inter-group comparisons. Significance was set at P≤0.05.

Conditions

• Root Resorption
• Orthodontic Appliance
• CBCT Segmentation

Interventions

DEVICE

Miniscrew insertion

four or two miniscrews insertions using computer-guided minimally-invasive and flapless approach

DEVICE

Expander

In the TB group, the tooth-borne hyrax appliance was designed with bands on the maxillary first molars; in the BB4 group, the bone-borne expander was supported by 4 miniscrews inserted both in paramedian and parapalatal position of the palatal vault; in the BB2 group, the bone-borne expander was supported by 2 miniscrews inserted in the paramedian region of the palate. The same type of expansion screw and expansion protocol were used in all groups. Specifically, a 10mm hyrax click screw (Dentaurum, Bologna, Italy) was activated by 4 quarter-turns on the first day and by 3 quarter-turns per day during the active phase of treatment (0.20mm per turn, 0.6mm daily) until an 8mm screw opening was achieved.

RADIATION

CBCT

All patients underwent CBCT examinations before the application of the RME device (T0) and post-treatment, after the 6-month retention period (T1). The exposure settings were as follows: 10 mA, 90 kV, total scanning time of 15.0 seconds, effective radiation time of 4.0 seconds, voxel size of 0.2 mm, scanning area of 14 x 16.5 cm, and an effective radiation dose of approximately 524 mGy/cm2. The CBCT images analyzed in this study were not acquired specifically for this research but were part of an ongoing prospective randomized clinical trial aimed at evaluating the skeletal and dentoalveolar effects of three different orthodontic devices. The imaging protocol was established in accordance with ethical guidelines and was approved by the relevant institutional review board.

Sponsors & Collaborators

• University of Roma La Sapienza

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

PARALLEL

Eligibility

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2023-03-01

Primary Completion

2023-10-01

Completion

2024-12-01

Countries

• Italy

Study Locations