Months Of Retention Research Articles

Periodontal tissue response among subjects with two different Nickel-Titanium fixed retainers during twelve months of retention

Objectives: This study aimed to compare changes in the lower dental arch after bonding two different shapes of Nickel titanium fixed retainers. The study was focused on whether the different shapes and sizes of retainers influence periodontal tissue response during one year of the post-treatment phase. Material and methods: Sixty subjects in total, of age (16-25), were randomly divided into two groups, every 30 subjects, upon finishing orthodontic treatment. Each group was divided into two subgroups according to growth factor (16-19) and (20_25) years old. First group FR was bonded Flat Nickel-titanium Retainer, thickness .010” x .029”, manufactured by Forestadent and to other 30 other subjects was bonded multistranded round Nickel -titanium retainer thickness ø 0.44mm/17”, manufactured by Dentaurum. Subjects had to come for checkups in 3,6,9, and 12 months, where four periodontal parameters were evaluated Plaque Index, Calculus Index, Gingival Index and Probing Depth. Results: There were statistically significant differences for the Plaque Index in favour of the Flat retainer. Also, the Gingival Index was higher in the Round retainer group but only after 12 months of retention. Pocket depth values increased in the first 3 months and then again showed the difference in the 12-month follow-up. Conclusions: Flat retainers showed less periodontal tissue response, lower Plaque Index, Gingival Index and less Pocket Depth compared to the Round retainers used in this study. But again, we found both types of fixed retainers initiate some periodontal response anyway.

Post-trauma complex orthodontic approach: the impact of psychological issues of bullying on treatment decision.

ABSTRACTObjective: This article aims to discuss the multidisciplinary approach required in the treatment of cases of impaction and ankylosis of permanent teeth, associated with a history of trauma, considering the psychological state of the child and family when faced with a traumatic case of bullying, by reporting the complex treatment of a central incisor needing to be orthodontically moved across the midline. Conclusion: This clinical case was a major challenge, which included complex multidisciplinary procedures. Results and stability after 26 months of retention indicated successful orthodontic space closure of two maxillary teeth, without the use of implants or prostheses, in an adolescent patient who had a history of dental trauma, alveolar bone loss, and an uncertain initial prognosis.

Invisalign System as a Treatment of a Skeletal Open Bite: A Case Report With a 5-Year Follow-up

Background: Orthodontic treatments of skeletal open bite are among the most challenging and at high relapse. Available therapies vary from behaviour-modifying appliances in growing patients to surgical approach in adults. Recently, clear aligners, such as Invisalign®, have also been proposed as a treatment modality, to be used alone or in combination with temporary anchorage devices. Case report: A 19-year-old female presented with 3-mm anterior open bite, peg-shaped upper lateral incisors, incorrect tongue posture at rest and during function. Due to aesthetic request, an orthodontic camouflage with Invisalign® was carried out for 17½ months, along with myofunctional therapy and composite veneers on upper lateral incisors. During the first months of retention, intermaxillary vertical elastics were maintained at night-time as positive feedback to the tongue. A 5-year follow-up confirmed stability of the results. Conclusions: A system of clear aligners in combination with myofunctional therapy was effective in the treatment of a skeletal open bite malocclusion, with stability at 5 years. The closure of the anterior open bite was obtained through a combination of lower molar intrusion, incisor extrusion and counterclockwise rotation of the mandible. In selected cases of optimal compliance, Invisalign® may constitute a feasible treatment option in management of open bite in non-growing patients.

One-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers.

To compare the clinical effectiveness of Hawley retainers (HRs) and modified vacuum-formed retainers (mVFRs) with palatal coverage in maintaining transverse expansion during a 12-month retention period. Data were collected from postorthodontic treatment patients who met the inclusion criteria. A total of 35 patients were randomly allocated using a centralized randomization technique into either mVFR (n = 18) or HR group (n = 17). The outcome assessor and data analyst were blinded to the retention method. Dental casts of patients were evaluated at debond, 3 months, 6 months, and 12 months of retention. Intercanine width (ICW), interpremolar width (IPMW), interfirst molar mesiobuccal cusp width 1 (IFMW1), and interfirst molar distobuccal cusp width 2 (IFMW2) were compared between groups over time using mixed analysis of variance. No statistically significant differences were found between the two groups for ICW (P = .76), IPMW (P = .63), IFMW1 (P = .16), and IFMW2 (P = .40) during the 12-month retention period. The null hypothesis could not be rejected. HR and mVFR had similar clinical effectiveness in the retention of transverse expansion cases during a 12-month retention period.

Treatment stability with bonded versus vacuum-formed retainers: a systematic review of randomized clinical trials.

In orthodontics, the retention phase can be considered challenging and unpredictable. Therefore, evidence obtained from different retention protocols is important to facilitate clinical decision-making. This systematic review aimed to compare the clinical effectiveness of bonded versus vacuum-formed retainers (VFRs) regarding their capacity to maintain treatment stability, periodontal effects, and failure rates. Ten databases comprising published and unpublished literature were systematically searched up to August 2021. Randomized clinical trials (RCTs) comparing both retainers were included. The risk of bias (RoB) evaluation was performed with the Cochrane Collaboration RoB Tool 2.0. All steps of the screening phase and RoB assessment were performed independently by two reviewers. The Grade of Recommendations, Assessment, Development, and Evaluation (GRADE) was used to evaluate the certainty of the evidence. Initial database search yielded 923 studies. After duplicates removal and full-text assessment, five RCTs remained. Overall, the studies presented Low RoB, except one study judged with 'Some concerns'. Based on the included studies, on a short-term (3-6 months) and long-term (4 years) basis, bonded retainers (BRs) were more effective to maintain treatment stability than VFRs in the lower arch. However, from 12 to 24 months both retainers presented the same efficacy. In the upper arch, the retainers were equally effective. BRs were associated with greater plaque and calculus accumulation than VFRs after 12 months. The retainers' failure rates were similar in the upper arch on the first year of retention; however, after 2 years VFRs showed significantly greater failure rates. Contrarily, BRs presented greater failure rates in the lower arch than VFRs. The findings of the included studies may be influenced by different factors related to the unpredictability of relapse. Most of the evidence generated in this systematic review derived from a moderate level of certainty. In the lower arch, BRs are more effective than VFRs to maintain treatment stability in the initial 6 months of retention and in the long term. In the upper arch, both retention protocols are equally effective. Regist0ration number: PROSPERO CRD42020199392. Coordination for the Improvement of Higher Educational Personnel (CAPES, Process code-001).

Differences in finished case quality between Invisalign and traditional fixed appliances.

To compare the treatment and posttreatment effects of Invisalign aligners that incorporated SmartForce features and attachments to traditional fixed appliances. This randomized controlled trial included 66 patients, 32 aligners, and 34 fixed-appliance patients. The median ages of the aligner and braces patients were 26.7 (interquartile range [IQR]: 9.8) and 25.9 (IQR: 16.6) years, respectively. Pretreatment occlusion was assessed using the ABO Discrepancy Index. Posttreatment (T1) and 6-month retention (T2) occlusions were quantified using the ABO Objective Grading System (OGS) scores. The braces group finished treatment significantly (P < .001) earlier (0.4 years) than the aligner group. The median DI scores for the aligner and braces groups were 4.5 and 7.0, respectively, which was a statistically significant (P = .015), but clinically insignificant, difference. There were no statistically significant between-group differences for the total OGS scores or any of the individual component scores at debond (T1) or after 6 months of retention (T2). During the posttreatment period, alignment and overjet worsened significantly in the aligner group, while buccolingual inclinations and occlusal relations improved. Over the same period, alignment worsened in the braces group and buccolingual inclinations improved. There was no statistically significant between-group difference in posttreatment changes of the total OGS scores. While patients with simple malocclusions require 4.8 months longer treatment times with aligners than traditional braces, the treatment and 6-month posttreatment occlusal outcomes are similar.

Voice changes after surgically assisted rapid maxillary expansion

This study aimed to investigate voice changes in patients who had surgically assisted rapid maxillary expansion (SARME). Nineteen adult patients with maxillary transverse deficiency were asked to pronounce the sounds "[a], [ϵ], [ɯ], [i], [ɔ], [œ] [u], [y]" for 3seconds. Voice records were taken before the expansion appliance was placed (T0) and 5.8weeks after removal (T1, after 5.2months of retention). The same records were taken for the control group (n=19). The formant frequencies (F0, F1, F2, and F3), shimmer, jitter, and noise-to-harmonics ratio (NHR) parameters were considered with Praat (version 6.0.43). In the SARME group, significant differences were observed in the F1 of [a] (P=0.005), F2 of [ϵ] (P=0.008), and [œ] sounds (P=0.004). The postexpansion values were lower than those recorded before. In contrast, the F1 of [y] sound (P=0.02), F2 of [u] sound (P=0.01), the jitter parameter of [ɯ] and [i] sounds (P=0.04; P=0.002), and the NHR value of [ϵ] sound (P=0.04) were significantly than the baseline values. In the comparison with the control group, significant differences were found in the F0 (P=0.025) and F1 (P=0.046) of the [u] sound, the F1 of the [a] sound (P=0.03), and the F2 of the [ϵ] sound (P=0.037). Significant differences were also found in the shimmer of [i] (P=0.017) and [ɔ] (P=0.002), the jitter of [ϵ] (P=0.046) and [i] (P=0.017), and the NHR of [i] (P=0.012) and [ɔ] (P=0.009). SARME led to significant differences in some of the acoustics parameters.

Skeletal effects of mini-implant assisted rapid palatal expansion (MARPE) on the sagittal dimensions of the maxilla an in-vivo cone-beam computed tomography (CBCT) study

Introduction -Transverse discrepancies of the maxilla are one of the most prevalent skeletal problems. Due to drawbacks of conventional RPE and invasive surgical expansion methods alternative methods were developed such as Mini Implant-supported rapid maxillary expansion (MARPE).Haas17 , Davis and Kronman18, Akkaya et al19 and many other studies have reported the maxillary response after MARPE on the sagittal dimensions, but their results were inconclusive.&#x0D; Aim - This study analyzed the effects on the maxilla in the sagittal dimension after Mini Implant assisted rapid palatal expansion (MARPE) in adolescents using CBCT.&#x0D; Material and method -A pretreatment CBCT image (T1) was taken as a standard initial record for all patients and post treatment CBCT (T2) was taken after three months in retention. The parameters SNA angle, Frankfort horizontal plane to NA angle, A-N perpendicular, ANS –PNS were measured and calculated for evaluation of the sagittal maxillary changes. Comparisons were then made between the two treatment groups (T1, T2).&#x0D; Result -There was a positive increase in both angular and linear measurements from pretreatment to post treatment measurements showing significant skeletal changes in sagittal dimension.&#x0D; Conclusion -The study concludes that there was statistically significant forward displacement of maxilla after transverse skeletal expansion in patients with transverse problems achieved through MARPE in adolescent patients.

Long-term changes in the anterior alveolar bone after orthodontic treatment with premolar extraction: A retrospective study.

To evaluate the morphometric changes in maxillary and mandibular anterior alveolar bone after orthodontic treatment and retention for 18-24months by cone-beam computed tomography (CBCT). Thirty-four adolescent patients (12 males and 22 females; mean age: 14.29±1.24years) diagnosed with bimaxillary dentoalveolar protrusion and with extractions of the 4 first premolars were included. The labial and lingual (palatal) alveolar bone thickness, height and root length of the maxillary and mandibular anterior teeth were assessed using CBCT imaging at the pre-treatment (T1), post-treatment (T2) and retention phases (T3). Voxel-based superimpositions of the T2 and T3 images were performed, and the distances of incisal and apical movement between T2 and T3 were measured to determine whether relapses occurred. After orthodontic treatment, the labial and lingual (palatal) bone height decreased significantly (P<.05) and the labial thickness at the crestal (L1), midroot (L2), and apical levels (L3) had no significant change, while the lingual (palatal) bone thickness at all three levels decreased significantly (P<.05). After 18-24months of retention, the lingual (palatal) height and the lingual (palatal) thickness at the crestal (L1) level increased significantly (P<.05). There were no obvious incisal and apical movements of the anterior teeth between T2 and T3 (P>.05), indicating that no relapses occurred. Even though lingual (palatal) alveolar loss occurred due to the orthodontic treatment, the cervical alveolar bone seemed to recover over time. Therefore, appropriate camouflage treatment can be used in patients with bimaxillary dentoalveolar protrusion, and this treatment will not irreversibly deteriorate periodontal health and affect the orthodontic treatment stability.

Treatment effects and biomechanical analysis of TMA spring appliance

Background/Aim Among Angle's classification, skeletal class III is the most difficult to treat. Treatment using the TMA spring intraoral appliance was investigated in the late mixed dentition and showed desirable effects. The present work aimed to investigate, biomechanically, the TMA spring appliance in the early mixed-dentition stage with specifically outlined force direction, duration, and magnitude in order to provide solid results that can be relied upon clinically. Patients and methods The sample consisted of 20 patients with an age range 8–10 years and an average of 8.6 years. Lateral cephalograms were taken and analyzed before treatment (T1), posttreatment (T2), and postretention (T3). The patients were instructed to wear the TMA spring appliance 12–16 h/day for 9 months, followed by 6 months of retention. The appliance delivered a force of 400 g/per side as measured with the force gauge. Results Comparing T1–T2 and T1–T3, there was a significant difference between sexes in points U6/S perpendicular; P=0013 and P=0.0159, SNA (P=0.0122, P=0.0371), and ANB (P=0.0491) at T1–T2. There was a significant difference in the whole sample for all the skeletal, dental, and soft-tissue measurements; P value less than 0.05, regarding treatment and retention changes. Conclusions The TMA spring appliance enhanced the cooperation of the patients, resulted in forward movement and clockwise rotation of the maxilla. Mandibular clockwise rotation and dentoalveolar changes also contributed to the overall correction of class III.

Evaluation of the Soft Tissue Changes after Rapid Maxillary Expansion Using a Handheld Three-Dimensional Scanner: A Prospective Study.

Facial soft tissue esthetics is a priority in orthodontic treatment, and emerging of the digital technologies can offer new methods to help the orthodontist toward an esthetic outcome. This prospective study aimed to assess the soft tissue changes of the face after six months of retention following Rapid Maxillary Expansion (RME). The sample consisted of 25 patients (13 females, 12 males, mean age: 11.6 years) who presented with unilateral or bilateral posterior crossbite requiring RME, which was performed with a Hyrax expander. 3D facial images were obtained before treatment (T0) and at the end of a six-month retention period after the treatment (T1) using a structured-light 3D handheld scanner. Linear and angular measurements were performed and 3D deviation analyses were done for six morphological regions of the face. Significant changes in various areas of the nasal and the upper lip regions were observed. Based on the results of the study and within the limitations of the study, RME with a Hyrax expander results in significant morphological changes of the face after a six-month retention period.

Herbst-multibracket appliance treatment: is there an association between lower incisor position changes and the development of labial gingival recessions?

PurposeTo assess a potential association between lower incisor (LI) position changes during Herbst–multibracket appliance (Herbst–MBA) treatment and the development of labial gingival recessions (LGR).MethodsAll class II patients (Department of Orthodontics, University of Giessen, Giessen, Germany) who had undergone Herbst–MBA treatment until 2015 with study models and lateral cephalograms available from before (T0) and after treatment plus ≥24 months of retention (T3) were included (n = 259). Lateral cephalograms were evaluated regarding LI position changes: iiL/ML (angle between LI long axis and mandibular plane [MP]), ii-MLPg (distance between LI incisal edge and a line perpendicular to MP through pogonion), apex-MLPg (distance between LI apex and a line perpendicular to MP through pogonion), ii-MLii (distance between LI incisal edge and MP on a line perpendicular to MP through incisal edge). Using study models the distance between the cementoenamel junction and the deepest point of the gingival margin was defined as LGR.ResultsThe following cephalometric mean changes were recorded (T0–T3): iiL/ML +5.9 ± 5.76° (p = 0.929), ii-MLPg −0.2 ± 0.25 mm (p = 0.430), apex-MLPg +0.1 ± 0.32 mm (p = 0.363), ii-MLii +0.1 ± 0.36 mm (p = 0.206). The mean increase of LGR magnitude measured on the study models was 0.1 ± 0.35 mm. However, no association with the cephalometric LI position changes was found (|R| ≤ 0.2).ConclusionThere is no association between the amount of LI position changes and the development of LGR during Herbst–MBA treatment plus retention. Nevertheless, individual predisposition or excessive treatment changes and extraordinary treatment approaches, respectively, might still lead to development of LGR.

Modulation of cortical activity in response to learning and long-term memory retrieval of 2D verses stereoscopic 3D educational contents: Evidence from an EEG study

Stereoscopic 3D (S3D) displays provide a very realistic visualization experience to the viewers through a sensation of depth perception. Despite the rapid growth of S3D technology (S3D) in education, very little has been known about the effects of S3D on human behavior and the corresponding brain's responses over traditional 2D display during conscious learning and Long-Term Memory (LTM) recall process. The present study aims to explore the effects of S3D technology on human behavior and the brain responses during learning and memory using an electroencephalography (EEG) technique. A sample of 68 participants between 18 and 30 years of age was recruited to perform three tasks: (1) Raven's Advanced Progressive Matrices (RAPM) test to assess the fluid intelligence ability; (2) learning task to study the S3D or 2D based contents for learning; and (3) memory recall task to assess the memory recall and retention performance. The participants were randomly assigned to two groups―2D group and S3D group, in such a way that their fluid intelligence ability, age, and background knowledge about the learning material are controlled. The analysis of behavioral data suggested that responses of both groups in terms of reaction time after two months of retention were statistically significantly different, F(2.66,125.09) = 4.47, p = .007, ηp2 = 0.087. The differences between the S3D and 2D groups were identified by EEG analysis, i.e., the classifier correctly discriminated the EEG signals of both groups with more than 90% accuracy rate. The EEG source analysis showed statistically significant differences between the groups in the brain regions of BA 7, BA 10, BA 11, and BA 25, reflecting widespread neuronal networks involved in the S3D group as compared to the 2D group in the LTM recollection. In conclusion, it was experimentally showed that the human brain processed the S3D contents differently by utilizing more cortical regions and neuronal networks than the traditional 2D contents, which modulates the behavior of the participants by recollecting the LTM faster in the recall task.

Vacuum-formed retainers and bonded retainers for dental stabilization-a randomized controlled trial. Part II: patients' perceptions 6 and 18 months after orthodontic treatment.

To compare removable vacuum-formed Essix C retainers with bonded cuspid-to-cuspid retainers (CTCs) regarding patients' perceptions after debonding and 6 and 18 months of retention. A single-centre two-arm parallel-group randomized controlled trial. This trial included 104 adolescent patients, computer-generated randomized, with sequentially numbered, opaque and sealed envelopes, into two groups and stratified by gender. They were treated with fixed appliances with and without tooth extractions in both jaws and were ready for debond. Patients in the intervention arm received a vacuum-formed retainer (VFR) in the mandible (n = 52), and patients in the active comparator arm received a CTC (n = 52). Both groups had a VFR in the maxilla. Treatment outcome satisfaction, quality of care and attention, side-effects during the retention phase, and retainer acceptance and compliance were assessed with questionnaires at baseline (T1, 2 weeks after debond) and after 6 (T2) and 18 months (T3) of retention. Operator was blinded to group assignment during measurements. Ninety-five patients completed the questionnaires at all three time points. Patients were overall satisfied with treatment outcome, quality of care and attention, and how their retainers worked at all three time points, with no differences between groups. At T1 and T3, the VFR group reported significantly more pain and discomfort (T1: P = 0.005, T3: P < 0.0001) and soreness (T1: P = 0.001, T3: P = 0.011) in the mandible compared to the CTC group. The CTC group found it easier to get used to their retainers. After 18 months, 70.5 per cent in the VFR group and 73.9 per cent in the CTC group reported the recommended wear-time of the VFRs. Decreased wear-time was correlated to perceived pain and discomfort (rs = -0.421, P < 0.0001). The results were limited by our retainer design and recommended wear regimen. Both groups reported high treatment outcome satisfaction and low levels of side-effects during the retention phase. Nevertheless, the VFR group reported more pain and discomfort at T1 and at T3. Self-reported compliance was the same in both groups. The VFR group was more concerned about relapse. NCT03070444 (https://clinicaltrials.gov).

Three-dimensional analyses of short- and long-term effects of rapid maxillary expansion on nasal cavity and upper airway: A systematic review and meta-analysis.

The purpose of this systematic review was to evaluate the three-dimensional (3D) changes occurring at short- and long-term follow-up after rapid maxillary expansion (RME) in nasal cavity (NC) and upper airway (UA) in growing patients. A literature search up to 1 July 2019 was performed. Randomized and non-randomized clinical trials and cohort studies comparing the effects of RME in a paediatric population using 3D analyses based on computed tomography (CT), cone-beam CT and MRI were included. The risks of bias of the included studies were assessed using the Cochrane Collaboration's risk of bias tool, the GRADE approach and a customized tool. The random-effects meta-analyses of the mean differences and 95% confidence intervals of NC and UA volume changes were carried out, followed by subgroup analyses. Twenty-seven studies were included, with 18 selected for quantitative synthesis. Immediately after expansion, the nasopharynx and oropharynx increased significantly. After 3months of retention, only the NC and nasopharynx showed a significant volume increase. Two studies mentioned the use of a sleep-disordered breathing questionnaire, and one study reported the difference before and after RME. None of the 27 articles included assessed the correlation between the skeletal widening and NC or UA volume changes after RME. The existing evidence confirmed only the short-term positive effect of RME on expanding the volume of the NC and the upper part of the UA. However, long-term stability could not be sustained.

Effects of symmetric and asymmetric rapid maxillary expansion treatments on pharyngeal airway and sinus volume.

To evaluate pharyngeal airway and maxillary sinus volumes following symmetric rapid maxillary expansion (RME) and asymmetric rapid maxillary expansion (ARME) treatment using cone-beam computed tomography (CBCT). The study consisted of 60 patients presenting to the orthodontics clinic with an indication that they required symmetric or asymmetric rapid maxillary expansion treatment. Individuals were included if they were aged 12-15 years and had symmetric (RME group; 14 girls, 16 boys) or asymmetric (ARME group; 16 girls, 14 boys) maxillary deficiency. Maxillary sinus volume (mm3) and pharyngeal airway volume (upper, lower, and total; mm3) were evaluated using CBCT records. The parameters were compared before treatment (T1) and after 3 months in retention (T2). All measurements at T2 were increased significantly compared with T1 in the RME group (P < .05). In the ARME group, changes in the lower pharyngeal airway and the nonaffected maxillary sinus volumes (non-affected side of maxillary sinus volumes) were not significant; however, the other measurements increased significantly from T1 to T2 (P < .05). Intergroup comparisons revealed that total pharyngeal airway volume and total maxillary sinus volume changes were significantly greater in the RME group. Pharyngeal airway and maxillary sinus volumes increased with both RME and ARME treatment. Both were found to be effective for treating transverse maxillary deficiency.

Orthodontic, periodontal and prosthodontic treatment for a periodontally compromised patient with a deep overbite

Abstract Background Periodontitis may result in displacement, overeruption and the tilting of teeth, which can lead to occlusal prematurities and accelerate the loss of periodontal structures. Orthodontic treatment is needed to correct displaced tooth positions, but inappropriate force and tooth movement can lead to further loss of supporting tissues. Aim To describe the treatment of a deep overbite in a 32-year-old male with a history of periodontitis, gingival recession and missing premolars. Methods After evaluation, fixed appliances applying light forces were chosen as the appropriate treatment approach. A segmental arch and a utility arch technique were applied. Periodontal therapy was conducted before and throughout orthodontic care. Results After 28 months of treatment, a normal overbite and overjet were restored. A displaced premolar was repositioned. Space needed for the prosthetic replacement of the missing teeth was obtained and dental implants were planned after orthodontic treatment. The height of the alveolar bone increased in some areas. After 18 months of retention, the attachment level of the upper left incisor increased approximately 1 mm. Conclusion For patients with a compromised periodontium, adequate management of the tissues is the basis of orthodontic care. Appropriate orthodontic treatment may be beneficial to periodontal health in the long term.

Vacuum-formed retainer versus bonded retainer for dental stabilization in the mandible-a randomized controlled trial. Part I: retentive capacity 6 and 18 months after orthodontic treatment.

Evidence concerning the most appropriate retention strategy after orthodontic treatment is still inconclusive. This trial compares the retentive capacity of vacuum-formed Essix C-retainers (VFR) and bonded cuspid-to-cuspid retainers (CTC) in the mandible 6 and 18 months after orthodontic treatment. A single-centre two-arm parallel-group randomized controlled trial. This study included 104 adolescent patients, computer-generated randomized with sequentially numbered, opaque, and sealed envelopes into two groups and stratified by gender (52 females and 52 males). The patients were treated with fixed appliances with and without tooth extractions in both jaws and were ready for debond. In the intervention arm, patients received a VFR (n = 52); in the active comparator arm, patients received a CTC (n = 52). Dental casts were obtained at debond (T1), after 6 months (T2), and after 18 months (T3). The casts were digitized. The retentive capacity was evaluated on digital three-dimensional models using Little's Irregularity Index (LII), overbite, overjet, arch length, and intermolar and intercanine width. Baseline values were similar for both groups. Statistically significant increases were noted in LII and overbite, mainly between T1 and T2, but also between T1 and T3 in the VFR group (LII = 0.52 mm, P < 0.001, overbite = 0.51 mm, P < 0.001) and in the CTC group (LII = 0.45 mm P < 0.001, overbite = 0.36 mm, P < 0.001). There were no significant differences between groups. Overjet showed small variations during the observation periods but was overall stable within and between groups after 18 months. Arch length decreased slightly in both groups after 6 and 18 months. Intermolar and intercanine widths remained stable after debond. Patients, operator, and outcome assessor could not be blinded due to the study design. VFR and CTC have the same retention capacity in the mandible after 6 and 18 months. Relapse mainly occurs during the first 6 months of retention, but the post-treatment changes are generally small. Shorter VFRs in the mandible do not cause negative vertical effects. Part-time wear regimen is not associated with increased relapse. NCT03070444.

Alternative approach using miniscrew-anchored sliding jig to correct maxillary midline deviation in a patient with unilateral missing premolar

This case report describes the use of a miniscrew-anchored sliding jig (SJ) to distalize molars in a patient with maxillary midline deviation. A 41-year-old female presented with a chief complaint of maxillary midline deviation toward the left caused by prior orthodontic treatment involving unilateral extraction of a maxillary left premolar. Clinical examination revealed facial symmetry and a straight profile. The maxillary midline was deviated 2.5 mm to the left. The patient was treated with molar distalization using miniscrew-anchored SJs. Midline correction and alignment were obtained with maxillary unilateral distalization and mandibular full-arch distalization. The total active treatment period was 32 months. Appropriate occlusion and centered midlines were maintained after 29 months of retention. Our results suggest that the treatment method described herein is effective to distalize the unilateral posterior segment in either arch.

Three-dimensional evaluation of surgically assisted asymmetric rapid maxillary expansion.

Unilateral posterior crossbite is classified as true unilateral posterior crossbite (TUPC) or functional posterior crossbite (FPC). The differential diagnosis between TUPC and FPC is of utmost importance for the decision of expansion protocol because conventional expansion methods have some shortcomings for TUPC. The aim of this retrospective study was to 3-dimensionally evaluate the effects of asymmetric rapid maxillary expansion combined with unilateral osteotomy. This study sample comprised 16 patients (mean age 18.38±1.45) with TUPC. A Hyrax acrylic cap included the maxillary premolars and molars on the constricted side, and all teeth up to the central incisor were included on the other side to increase anchorage. Unilateral surgically assisted rapid maxillary expansion was performed and included anterior (aperture piriformis), lateral (zygomatic buttress), and posterior (pterygomaxillary junction) osteotomies on the constricted side and separation of the midpalatal suture. Cone-beam computed tomographic scans taken just before the operation and after 6months of retention were used to assess skeletal, dental, and periodontal changes. Expansion was seen on both sides; however, the amount of expansion and tipping was higher on the osteotomy+side. Because the canines were not included in the acrylic cap on the osteotomy+side, they did not present the same amount of tipping as the ipsilateral posterior teeth. More teeth were affected periodontally on the osteotomy- side; however, there were no clinically significant differences between the osteotomy+ and osteotomy- sides (mean differences range+0.54 to -0.57mm). The aperture piriformis width increased significantly on the osteotomy+side. The treatment mechanics had no clinically detrimental effects on the supporting alveolar bone of the maxilla on either side, and it was thought to be effective in cases with TUPC; however, case selection is crucial.