ABSTRACT

Objectives

To compare mandibular relative anchorage loss (RAL) under reciprocal anchorage between first and second premolar extraction cases in bimaxillary protrusion mild crowding cases treated using clear aligner therapy (CAT).

Materials and Methods

Adult patients who met the following criteria were included: treated using CAT with bilateral mandibular premolar extractions and space closure using intra-arch reciprocal anchorage. RAL was defined as the percent molar mesial movement relative to the sum of molar mesial plus canine distal movement. Movements of the mandibular central incisor (L1), canine (L3), and first molar (L6) were measured based on superimposition of the pre- and post-treatment dentition and jaw models.

Results

Among the 60 mandibular extraction quadrants, 38 had lower first premolar (L4) and 22 had lower second premolar (L5) extracted. L6 mesial movement was 2.01 ± 1.11 mm with RAL of 25% in the L4 extraction group vs 3.25 ± 1.19 mm with RAL of 40% in the L5 extraction group (P < .001). Tooth movement efficacy was 43% for L1 occlusogingival movement, 75% for L1 buccolingual inclination, 60% for L3 occlusogingival movement, and 53% for L3 mesiodistal angulation. L1 had unwanted extrusion and lingual crown torquing whereas L3 had unwanted extrusion and distal crown tipping, on which the power ridges or attachments had little preventive effect.

Conclusions

The average mandibular reciprocal RAL is 25% or 40% for extraction of L4 or L5, respectively, in CAT cases. A RAL-based treatment planning workflow is proposed for CAT extraction cases.

ABSTRACT

Objectives

To compare maxillary canine retraction between healed and recent extraction sites by assessing movement rate, canine dentoalveolar changes, molar rotation, and anchorage loss using cone-beam computed tomography (CBCT).

Materials and Methods

Twenty-eight patients (16–26 years old) who had bimaxillary protrusion and orthodontic treatment planned with extraction of first premolars were randomly distributed into two groups and treated using a straight wire appliance. In the recent group (RG), the upper first premolars were extracted 2 weeks before the initiation of canine retraction (after tooth alignment). In the healed group (HG), the upper first premolars were extracted before tooth alignment. Movement rate, canine dentoalveolar changes, molar rotation, and anchorage loss were assessed using CBCT.

Results

Movement rate, canine alveolar bone dimensions, canine rotation, and rotation and mesial movement of the first molar were not significantly different between groups (P > .05). Canine tipping was greater in RG (P = .001).

Conclusions

Retracting canines into recent extraction sites compared with healed sites showed greater distal tipping of the canine with no differences in movement rate, canine alveolar bone dimensions, canine rotation, molar rotation, and anchorage loss.

ABSTRACT

Objectives

To compare skeletal and dentoalveolar changes of miniscrew-assisted rapid palatal expansion (MARPE) according to the length of the miniscrews.

Materials and Methods

This two-arm parallel-randomized controlled trial included 32 adult patients aged 19–35 years who received orthodontic treatment with MARPE. Patients were allocated to two groups, group long (L) and short (S), through block randomization according to the length of the miniscrews installed in MARPE. Cone-beam computed tomography was performed before expansion and after removal of the MARPE; superimposition of the images was conducted. The primary outcome included the amount of bone expansion and the change in the inclination of the anchorage teeth. The secondary outcome included the success rate of midpalatal suture opening and stability of the miniscrews. Blinding was performed during outcome assessment.

Results

The final sample comprised 31 patients. There was no significant difference in patient characteristics between group L (n = 16) and group S (n = 15). The change in the width of the processus zygomaticus (P = .010) and ectocanine (P = .001) was significantly higher in group L. A significantly higher success rate of the posterior miniscrews was seen in group L (P = .024). There was no statistically significant difference in the success rate of suture separation or change in tooth inclination. Notable complications were not reported.

Conclusions

MARPE with longer miniscrews can increase the amount of expansion of the maxillary basal bone and canine alveolar bone. Although it also aided in miniscrew stability, it did not guarantee successful midpalatal suture separation.

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NEW JERSEY

Rutgers, The State University of New Jersey

Rutgers School of Dental Medicine

110 Bergen St.

Newark, NJ 07101

Apply online: https://jobs.rutgers.edu/postings/150461

Posting Number: 21FA1514

For more info email Mr. Christian Cardenas at: cardenca@sdm.rutgers.edu

Rank: Clinical Assistant Professor (Part-Time, 2-days per week).

Requirements: DDS/DMD from an accredited institution. Completion of an advanced education program in orthodontics at an institution accredited by the Commission on Dental Accreditation, and eligibility for licensure in New Jersey. American Board of Orthodontics certification and previous

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