ABSTRACT

Objectives

To evaluate the angular and positional changes of the maxillary second (M2) and third molars (M3) after orthodontic premolar extraction treatment according to patient skeletal classification and growth pattern.

Materials and Methods

Panoramic radiographs of patients treated with extraction of the first or second premolars (n = 116) and patients treated without extraction (n = 92), taken before orthodontic treatment (T0) and after completion of multibracket appliance therapy (T1) were analyzed. Angle classification, growth pattern, crowding, and incisor inclination were recorded. The palatal (PP) and interorbital planes (IOP) were used as reference lines. Changes in the M3 angulation relative to PP and IOP (T0–T1) within the same group were evaluated with paired t-tests. One-way analysis of variance (ANOVA) and Kruskal-Wallis tests were used for comparisons between the groups. Accordingly, pairwise comparisons were performed with Mann-Whitney U-tests or independent t-tests (P < .05).

Results

The M3 angulation related to the PP and the IOP did not differ significantly between the extraction and nonextraction groups. The M2 angulation improved in the premolar extraction group between T0 and T1 (M2/PP, P < .001). According to Archer's classification, the change in the vertical position of M3 differed significantly between the extraction and nonextraction groups (P < .001).

Conclusions

The angulation of M3 improved over time regardless of the extraction decision. The vertical eruption pattern of M3 was positively influenced only in the extraction group. M2 became significantly more upright in the orthodontic extraction treatment groups.

ABSTRACT

Objectives

To identify predictors regarding the type and severity of malocclusion that affect total Invisalign treatment duration based on an intraoral digital scan.

Materials and Methods

The subjects of this retrospective clinical cohort were 116 patients treated with Invisalign. A deep learning method was used for automated tooth segmentation and landmark identification of the initial and final digital models. The changes in the six degrees of freedom (DOF), representing types of malalignment, were measured. Linear regression was performed to find the contributing factors associated with treatment time. In addition, the Peer Assessment Rating (PAR) score and a composite score combining 6 DOF were correlated separately to the treatment time.

Results

The number of trays differed between sexes (P = .0015). The absolute maximum torque was marginally associated with the total number of trays (P = .0518), while the rest of the orthodontic tooth movement showed no correlation. The composite score showed a higher correlation with the total number of trays (P = .0045) than did individual tooth movement. Pretreatment upper and lower anterior segment PAR scores were positively associated with the treatment time (P < .001).

Conclusions

There is not enough evidence to conclude that certain types of tooth movement affect the total aligner treatment time. A composite score seems to be a better predictor for total treatment time than do individual malalignment factors in aligner treatment. Upper and lower anterior malalignment factors have a significant effect on the treatment duration.

ABSTRACT

Objectives

To compare patient-reported experience between a Penn expander activated every other day vs twice daily.

Materials and Methods

A total of 30 patients aged 12–16 years with transverse maxillary deficiency were recruited from the outpatient clinic, Faculty of Dentistry, Alexandria University (February 2019–December 2020). They were randomly allocated to two groups using block randomization (block size of six) and an allocation ratio of 1:1, which was concealed using opaque, sealed, sequentially numbered envelopes. Both groups received Penn expanders anchored by four palatal miniscrews. The slow maxillary expansion (SME) group activated the appliance once every other day. The rapid maxillary expansion (RME) group activated the appliance twice daily. Outcome measures were pain, pressure, headache, dizziness, speech difficulty, chewing difficulty, and swallowing difficulty scores rated by the participants on an 11-point numeric rating scale (NRS) at the following four time points: before appliance insertion (t₁), after first activation (t₂), after 1 week of activation (t₃), and after last activation (t₄).

Results

Data of 24 patients in the SME group (n = 12, mean age = 14.30 ± 1.37 years) and RME group (n = 12, mean age = 15.07 ± 1.59 years) were analyzed. Median scores for all outcomes were in the bottom quartiles of the NRS. No difference was found between the two groups at t₁ or t₂. Significantly higher scores for all variables, except dizziness and headache, were reported in the RME group at t₄.

Conclusions

Activation of miniscrew-supported expanders resulted in mild to moderate discomfort and functional limitation. Slow activation resulted in a better overall patient experience compared with rapid activation.

This listing of academic opportunities is provided as a free service to the profession and the community.

CALIFORNIA

University of the Pacific

Arthur A. Dugoni School of Dentistry

Department of Orthodontics

155 5th Street

San Francisco, CA 94103

Apply: https://pacific.peopleadmin.com/23945

Rank: Full-time, Assistant/Associate Professor

Requirements: DMD/DDS or equivalent and Certificate in Orthodontics and a Master of Science degree or equivalent; a strong academic teaching and scholarly activity record.

MASSACHUSETTS

Boston University Henry M. Goldman School of Dental Medicine

Department of Orthodontics & Dentofacial Orthopedics

635 Albany Street, Suite 754

Boston, MA 02118

Email applications to: willa@bu.edu

Rank: Clinical