Tip, torque and rotation of maxillary molars during distalization using Invisalign: a CBCT study.

BACKGROUND: Desirable molar distalization by bodily movement is challenging and can be difficult to achieve. This study investigated changes in molar angulation (mesiodistal tipping), molar inclination (buccolingual torque) and rotation during distalization using clear aligner therapy (CAT). MATERIALS AND METHODS: This retrospective study included 38 cone beam computed tomographic images (CBCTs) taken for patients treated with molar distalization using CAT. The study evaluated pre- (T0) and post-treatment (T1) CBCTs of 19 adult patients (36.68 ± 13.50 years) who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization. Changes in maxillary molar tip, torque and rotation were measured for 61 molars (183 roots). Paired t-test was used to evaluate the differences between pre- and post-treatment readings. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by the intraclass correlation coefficient (ICC). RESULTS: Molar angulation did not show significant change after distalization (p = 0.158) however, there was significant increase in buccal molar inclination (p = 0.034) and mesiobuccal molar rotation (p < 0.001). CONCLUSION: Molar distalization of 2 mm did not cause significant molar tipping. Maxillary molars showed significant buccal inclination (increased torque) and mesiobuccal rotation after distalization.

Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners.

AIM: The purpose of this study was to evaluate the mandibular growth and/or projection following maxillary incisor proclination, overbite correction, and maxillary dentoalveolar expansion without the use of any class II mechanics, in growing class II division 2 patients treated with clear aligners. MATERIALS AND METHODS: Before and after treatment cone-beam computed tomographic (CBCT) generated lateral and posteroanterior cephalograms of thirty-two patients with skeletal class II division 2, 16 in the treatment group and 16 in the untreated group, were reviewed to evaluate treatment-related changes. Upper incisors were proclined and protruded, as well as upper arch expansion and overbite correction were performed as part of their regular treatment. Cephalometric analysis was performed to evaluate skeletal and dental changes. Unpaired statistical t-tests were performed to determine if significant skeletal class II correction was achieved in the treatment group. RESULTS: In the treatment group, after treatment, the upper incisors became more proclined and protruded, and the inter-molar width increased while the overbite was reduced compared to the control group. An increase in skeletal mandibular growth and forward projection was also observed, thus contributing to an improvement of the sagittal skeletal relationship as evidenced by ANB and Wits values compared to the control group. CONCLUSION: A combination of upper incisor proclination, correction of deep overbite, and maxillary dentoalveolar expansion using clear aligners appears to contribute to an improvement of the skeletal class II relationship in growing patients with class II division 2. CLINICAL SIGNIFICANCE: This study shows that unlocking the mandible by correcting a deep overbite, proclining upper incisors, and expanding the upper arch in growing class II division 2 patients can improve skeletal class II using clear aligners. How to cite this article: Mirzasoleiman P, El-Bialy T, Wiltshire WA, et al. Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners. J Contemp Dent Pract 2024;25(4):295-302.

Does short-term treatment with clear aligner therapy induce changes in muscular activity?

DESIGN: Prospective cohort study. COHORT SELECTION: The inclusion criteria comprised patients older than 18 years who attended the orthodontic department at the University of L'Aquila (L'Aquila, Italy) and requested treatment with clear orthodontic appliance. Only patients with Class I malocclusion with mild (0-3 mm) or moderate (4-6 mm) crowding were included. The exclusion criteria comprised patients who had medical condition that preclude the use of surface EMG (sEMG), patients who had anterior or posterior open bite, patients who had cross bite that include more than one tooth, patients who had edentulous ridges and patients with temporomandibular disorder. DATA ANALYSIS: Included patients were assessed at three points in time: at the start of treatment (T0), after 3 months (T1), and after 6 months (T2). The patients were instructed during the study to wear each set of aligners (Nuvola; Gruppo Europeo di Ortodonzia S.r.l., Rome, Italy) for 2 weeks and 22 h/d and to remove them while eating and drinking (except for still water). The following two assessments were done for each patient at T0, T1, and T2: surface electromyography (sEMG) evaluation and a T-Scan digital occlusal analysis evaluation. Both evaluations were performed in centric occlusion and with aligners worn. The assessments were done by the same operator. The sEMG evaluation aimed to assess the muscular symmetry and balance. The sEMG evaluation was performed using an instrument that recorded analogical sEMG signal (BTS TMJOINT, Teethan S.p.a., Garbagnate Milanese, Milano, Italy). The patients were instructed to clench as much as possible and to maintain the same level of contraction during the test. The software automatically selected the 3 s with the most stable sEMG signal. The following outcomes were assessed using the sEMG: 1. Masseter percentage overlapping coefficient (POC), temporalis POC, and mean POC: which is an index of the symmetrical distribution of sEMG potentials within homologous muscular couples. 2. Torque coefficient (TC): compares the activity of the temporalis muscle to that of the contralateral masseter muscle. 3. Activity index (Ac): compares the activity of the temporalis muscle to that of the homolateral masseter muscle 4. Asymmetry index (Asym): compares the activity of the temporalis and masseter muscles of the right side to those of the left side. The digital occlusal analysis was performed using a 100µ thin, flexible horseshoe-shaped Mylar sensor (Novus HD sensor, Tekscan, Inc. S. Boston, MA, USA) that is used to analyze the dynamic and real-time distribution and timing of occlusal contacts and can reproduce 256 levels of varying occlusal force. A first recording was made without aligners, then a second with the aligners worn on the dental arches. The following outcomes were assessed using the digital occlusal analysis: 1. Position of the center of occlusal force (COF). 2. The maximal intercuspation time (MIC) (i.e., the time interval expressed in seconds between the first dental contact and the maximal intercuspation). The null hypothesis was that no difference exists for the sEMG indexes between the 3-time points and the two occlusal conditions. RESULTS: Twenty-six female adult patients (mean age, 33.67 ± 13.33 years) were enrolled in this study. Statistically significant differences were observed in terms of POC for the temporalis and masseter muscles, as well as the mean POC across the three time points and between occlusal conditions (with or without aligner). Hence, null hypothesis was rejected. On the other hand, TC, Ac, Asym, and MIC variables did not exhibit any statistically significant differences. This confirms that the stable positioning of COF on the transverse plane was accompanied by the absence of torquing muscular couples or imbalances in muscular activation. Symmetry in muscular couples' activation (indicated by POC value) remained consistent over the 6-month follow-up period for the occlusion with aligners, and in fact, demonstrated some improvements. In contrast, there was a decline in POC over time during centric occlusion. Statistically significant variation in COF position was observed in the sagittal plane, but not in the transverse plane. This shift in COF position coincided with changes in muscular balance as assessed by surface electromyography. Regarding the anteroposterior position of the COF, an overall slight posterior shift was observed when aligners were worn. After 3 months of full-time aligner usage, an anterior COF position was detectable in centric occlusion, which exhibited statistical significance when compared with the occlusion involving aligners at T0 and T1. CONCLUSIONS: The use of clear aligners led to an anterior displacement of the COF during biting in centric occlusion, along with a posterior shift while the aligners were worn in healthy female subjects over a 6-month monitoring period. No significant asymmetries in the COF position on the transverse plane were observed. The alterations in occlusal contact were subsequently followed by a short-term improvement in muscular balance when aligners were used, but a worsening muscular balance over time in centric occlusion condition.

Impact of clear aligner therapy on speech: does clear aligner therapy cause any speech difficulty?

DATA SOURCES: Electronic search was conducted up to September 2021 in three electronic databases including Scopus, Web of Science, and EMBASE. Only studies in English language were selected. STUDY SELECTION: Prospective and retrospective studies including cohort, cross-sectional, randomized control trials, and qualitative studies were included. Both the inclusion and exclusion criteria were reported. The search in the databases and the selection of the studies were performed independently by two reviewers. The included studies assessed the effects of clear aligner therapy on the speech difficulty. DATA EXTRACTION AND SYNTHESIS: Data extraction was performed independently by two reviewers. The data from the relevant studies were extracted into a customized Template. The systematic review was carried out and reported based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. Details regarding the authors, year of publication, sample size, included participants, age, groups, outcome assessment, results, and inferences were extracted from the selected studies. The quality of the selected studies was assessed based on the relevant guidelines from Cochrane Handbook for Systematic Reviews. The criteria examined sequence generation, allocation concealment, blinding, outcome data, selective reporting, and other sources of bias. Non-randomized studies were assessed using the ROBINS-I tool (Risk of Bias in Non-randomized studies). The strength of evidence was assessed by the evidence grading system developed by the GRADE collaboration as described in the Cochrane Handbook for Systematic Reviews of Interventions. RESULTS: The search identified 283 results. 269 articles were excluded based on their title and abstract after evaluation against the inclusion criteria. 14 articles were assessed in full text. Finally, 7 papers were included in the qualitative analysis. The included studies were 5 cohort studies and 2 randomized clinical studies. 332 patients were examined in the included studies. There were 195 females and 137 males. 191 patients were treated using clear aligner therapy (CAT) while 122 patients were treated using labial fixed appliances and 19 patients were treated using lingual orthodontic treatment. Out of the 191 patients who were treated using CAT, 179 patients were treated using Invisalign (Santa Clara, CA, USA) while 12 patients were treated using Smile Align (Mumbai, India). All seven selected studies examined speech dysfunction. The speech difficulty was assessed through two tools - semiobjective assessment by speech pathologists and professionals and subjective evaluations by the patients themselves through a patient questionnaire that assess the effects of aligners on speech. The risk of bias assessment revealed that two studies had moderate risk of bias while five articles had serious risk of bias. Meta-analysis was not performed due to the high heterogeneity of the included studies. The level of evidence was assessed as low due to the methodological insufficiencies and risk of bias in the included studies. The results showed that both CAT and fixed appliances (FA) resulted in speech difficulties in terms of clarity and delivery of speech that include speech alteration, slurring of words, lisping, and nasality. Some patients who were treated using CAT reported impairment in the lingual space that affected their speech. Lingual FA resulted in more speech difficulty when compared to labial FA and CAT. Aligners caused errors in the articulation of /s/,/z/,/zh/,/sh/,/th/,/ch/. Acoustic analysis revealed /s/ sound appeared most affected. Aligners had an effect on speech while reading, with patients slowing down to their speed to better articulate. The above-mentioned speech difficulties were transient. The included patients normalized their speech within 7-14 days from start of treatment while few patients took 30-60 days to recover. CONCLUSIONS: Although the likelihood of speech difficulties would be high with CAT, the current evidence states that speech difficulties shown with CAT are similar to those found with FA. However, the patients who were treated using CAT adapt quickly and speech recovers within a few weeks. Time to recovery varied greatly, ranging from a week to two months in certain cases.

Association between nonextraction clear aligner therapy and alveolar bone dehiscences and fenestrations in adults with mild-to-moderate crowding.

INTRODUCTION: This study aimed to assess the association between nonextraction clear aligner therapy (CAT) and the presence of alveolar bone dehiscences (ABDs) and fenestrations (ABFs) in adults with mild-to-moderate crowding. METHODS: Cone-beam computed tomography images from 29 adults were obtained before and immediately after nonextraction CAT. Total root lengths were evaluated in axial and cross-sectional slices. Linear measurement for dehiscence (LM-D) was defined as the distance between the alveolar crest to the cementoenamel junction of each root (critical point set at 2 mm). Linear measurement for fenestration (LM-F) was recorded when the defect involved only the apical one-third of a root (critical point set at 2.2 mm). Counts of ABDs/ABFs and magnitudes of LM-Ds/LM-Fs were recorded before and immediately after nonextraction CAT at buccal and lingual root surfaces. Binary logistic regression analyses and repeated measures analyses of variance were performed. RESULTS: Counts of ABDs/ABFs and magnitudes of LM-Ds/LM-Fs increased at most jaw locations and root surfaces. Nonextraction CAT was associated with an increased presence of ABDs and ABFs. Nonextraction CAT was associated with a higher magnitude of LM-Ds but not LM-Fs. CONCLUSIONS: Immediate posttreatment cone-beam computed tomography scans showed that nonextraction CAT is associated with increased ABDs and ABFs in adults with mild-to-moderate crowding.

The effect of clear aligners on speech: a systematic review.

OBJECTIVE: To assess the effect of clear aligners on the speech of patients undergoing orthodontic therapy through a systematic review of the literature. Search methods and selection criteria: The protocol of this systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) CRD42021278694. An electronic search of the Scopus, Embase, Pubmed, and Web of Science databases was done for papers published between January 2000 till September 2021. Studies that evaluated speech difficulties in patients undergoing orthodontic treatment with clear aligners using objective and subjective analyses were included. The evaluated primary outcome was speech difficulties. Secondary outcomes were time to adaptation and recovery from speech difficulties. Study quality was assessed based on the Cochrane Handbook for Systematic Reviews of Interventions Handbook guidelines and ROBINS-I tool. RESULTS: Two hundred and eighty-three articles were screened to identify seven studies (n = 332 patients) that assessed speech difficulty with aligners, of which two were randomized trials. Meta-analysis was not performed due to the heterogeneity in the study designs. Five studies compared speech difficulty with aligners to fixed appliances. Two studies showed a moderate risk of bias and five studies had a serious risk of bias. Level of evidence was downgraded to low due to the methodological insufficiencies and risk of bias in the studies. All seven studies reported that aligners could influence the clarity and delivery of speech, similar to fixed appliances. Various phonemes were affected including /s/,/z/,/zh/,/sh/,/th/,/ch/ on wearing aligners. Errors in articulation of consonants and sibilants were noted with lisping and speech impairment. These speech difficulties were temporary and most patients recovered in 7-14 days while few patients took 30-60 days to recover. CONCLUSION: The likelihood of speech difficulties appears high with clear aligners. However, patients adapt quickly and speech returns to normal. The results of this review must be interpreted with caution and more well-designed randomized trials examining long-term effects of aligners on speech are indicated. CLINICAL SIGNIFICANCE: Orthodontists should counsel patients opting for clear aligner treatment of the potential transient speech difficulties. REGISTRATION: The protocol for this systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) CRD42021278694.

Does maxillary sinus proximity affect molar root resorption during distalization using Invisalign? a CBCT study.

BACKGROUND: This study aimed to assess the correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption during molar distalization using clear aligner therapy (CAT). MATERIALS AND METHODS: Thirty-eight cone beam computed tomography scans (CBCTs) obtained pre- (T0) and post-treatment (T1) from 19 adult patients (36.68 ± 13.50 years), who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization, were evaluated in this study At least 22 h of aligner wear per day was a main inclusion criterion. Sinus proximity and changes in root lengths were measured for 61 molars (183 roots). Spearman coefficient analysis was used for assessing correlation between sinus proximity and root resorption. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by intraclass correlation coefficient (ICC). RESULTS: Spearman coefficient revealed no significant correlation between sinus proximity and molar root resorption for mesiobuccal, distobuccal or palatal roots (p = 0.558, p = 0.334, p = 0.931, respectively). CONCLUSION: There was no correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption.

Does motivation via a smartphone application improve oral hygiene in patients undergoing orthodontic treatment?

DESIGN: This is a randomized cohort study. COHORT SELECTION: The inclusion criteria comprised patients aged 14-19 years who started their orthodontic treatment using fixed appliances at the Orthodontic Clinic at Universidade Cruzeiro do Sul, San Paulo, Brazil. Only patients who had smartphones were included in this study. The exclusion criteria comprised patients who had previous orthodontic treatment, presence of any oral pathology, and chronic use of analgesic medication or presence of syndromes. Included patients were randomized to two groups (control and experimental). DATA ANALYSIS: The oral hygiene of the included patients was evaluated clinically at five points in time: before bonding fixed orthodontic appliance (T0), immediately after randomization (T1), at 30 days after the beginning of the intervention (T2), at 60 days after the beginning of the intervention (T3), and at 90 days after the beginning of the intervention (T4). Oral hygiene was assessed using visual plaque index (VPI) and gingival bleeding index (GBI) at six sites of all teeth in every arch excluding third molars. Prior to the intervention, all patients who participated in this study underwent an oral hygiene session aimed to obtain a plaque index equal to zero and were given standardized oral hygiene instructions. Patients included in the control group were not given any structured oral hygiene follow-up in addition to the standard follow-up already established at the orthodontic clinic. Patients in the experimental group were instructed to install an application (A Dentista Cientista) that was designed especially for this study on their smartphones. This application aimed to guide and motivate patients daily in a playful way about performing oral hygiene practices. The application reminded the patients to perform their oral hygiene through an alarm. RESULTS: A total of 11 patients were screened for study eligibility; 3 patients were excluded from the study. Eight patients were included in this study, four patients in each group. Although VPI and GBI values were reduced at T1 and T2 in the experimental group, there were no statistically significant differences for VPI and GBI between the groups at any time evaluated (P > 0.05). The patients who were included in the experimental group reported a good acceptability of the application and they would recommend it to other people. In addition, the patients who were included in the experimental group agreed that oral hygiene is crucial and 75% of them agreed that the application encouraged them to take better care of their oral health. CONCLUSIONS: This study showed that mobile applications might help in improving the oral hygiene of orthodontic adolescent patients.

Evaluation of Orthodontic Mini-Implant Placement in the Maxillary Anterior Alveolar Region in 15 Patients by Cone Beam Computed Tomography at a Single Center in South India.

BACKGROUND In this study, we aimed to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region by cone beam computed tomography (CBCT) in 15 patients at a single center in South India. MATERIAL AND METHODS A total of 15 CBCT scans of orthodontic patients after completion of leveling and aligning stage were included. The thickness of labial alveolar bone, labio-palatal bone, and inter-radicular distance between the maxillary central incisors (U1-U1), maxillary central and lateral incisor (U1-U2), and maxillary lateral incisor and canine (U2-U3) at vertical levels 4 mm, 6 mm, and 8 mm above the interdental cementoenamel junction were measured. Descriptive statistics, ANOVA, and Tukey post hoc tests were done to assess the differences among the groups. An independent t test was done to analyze differences by sex. RESULTS The thickness of cortical bone in the labial region was higher in the U2-U3 site than in the U1-U1 site, at a height of 4 mm. Also, there was a significant difference between 4 mm and 8 mm heights in the U2-U3 region. No significant difference was noted in bone dimensions among men and women and in the labio-palatal bone thickness among the different sites. The inter-radicular distance was the highest between the U2-U3 site, while it was the lowest in the U1-U2 site. CONCLUSIONS The findings from this center showed that when CBCT was used to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region, the U2-U3 and U1-U1 locations at heights between 6 mm to 8 mm apical to the interdental cementoenamel junction were optimal for placement of the mini-implants.

Skeletal and dental effects of Herbst appliance anchored with temporary anchorage devices: A systematic review with meta-analysis.

BACKGROUND: The aim was to evaluate the efficiency of using temporary anchorage devices (TADs) in minimizing the anchorage loss and increasing the skeletal effects during correction of Class II malocclusion with Herbst appliance. MATERIALS AND METHODS: Search without restrictions was performed up to January 2021 in three electronic databases (CENTRAL, MEDLINE and EMBASE) for randomized controlled trials (RCTs), prospective and retrospective cohort studies. The included studies assessed the dental and skeletal changes in Class II malocclusion patients who were treated using Herbst appliance with or without TADs. The strength of evidence was ranked using GRADE. RESULTS: Fifty-five records were initially retrieved. A total of 6 studies with 198 patients were finally considered. 4 studies were included in the meta-analysis. The meta-analysis showed that using TADs with acrylic splint Herbst appliance was effective in controlling the inclination of mandibular incisors by a mean difference of -5.49 degrees (95% C.I [-7.36, -3.63], P < .001) when compared to Herbst appliance alone. The results showed also that incorporating TADs with Herbst treatment resulted in greater mandibular skeletal effects including increasing mandibular bone base length by mean difference of 2.22 mm (95% C.I [0.82. 3.61], P = .002) and mandibular length by mean difference of 3.7 mm (95% C.I [1.55, 5.85], P < .001) when compared to Herbst appliance alone. CONCLUSIONS: Based on a very low level of confidence, it seems that incorporating TADs during orthodontic treatment with Herbst appliance results in minimizing the anchorage loss and increasing the skeletal effects of Herbst appliance during correction of Class II malocclusion.

Saturdays Orthodontic Appointments, Demand, and Patients' Commitment.

AIM: The purpose of this study was to determine the demand for orthodontic appointments on weekends and the level of commitment the patients have for those appointments. MATERIALS AND METHODS: A survey of 17 questions was created and given to 199 adult patients. The first six questions addressed demographic information, followed by three questions addressing whether coming to their orthodontic appointments required taking time off of work. The remaining questions asked if they would prefer to attend orthodontic appointments on Saturday if they would take advantage of a Saturday appointment, and what their preferred time and level of commitment would be for this appointment. The data were analyzed using the logistic-regression Chi-square test. RESULTS: About 77.4% of the participants indicated that they would take advantage of appointments on Saturdays if available. The most preferred time for Saturday appointments was 7:00 am-10:00 am, followed by 10:00 am-12:00 pm. About 60.6% of the participants reported that they would be willing to sign up for AutoPay in order to be seen on Saturday. Among those who would take advantage of weekend appointments, 82.6% reported that they would likely never miss or reschedule a Saturday appointment, and 75.3% would choose an orthodontist who is open on Saturday over another orthodontist who is not. Among participants who work more than 40 hours per week, 86.1% (106) wanted to take advantage of Saturday appointments. Participants with a high household income are less inclined to take advantage of Saturday appointments compared with those with a low household income. Participants who need to take time off of work are more inclined to take advantage of Saturday appointments [93% (106) favorable vs 7% (8) unfavorable]. Participants who need to take their child out of school early for their orthodontic appointments during the week are more inclined to take advantage of Saturday appointments [87% (97) favorable vs 13% (15) unfavorable] than those who do not need to. CONCLUSION: There is a demand for Saturday orthodontic appointments with a very high commitment level among the majority of those patients. The Saturday demographic tends to be participants with a low household income who work 40 or more hours per week. CLINICAL SIGNIFICANCE: Orthodontic offices may consider working at least one Saturday per month to satisfy patient needs. They can use this survey to explore their own market for Saturday clinical practice.

Do orthodontic treatments using fixed appliances and clear aligner achieve comparable quality of occlusal contacts?

Design Non-randomised cohort study.Cohort selection The inclusion criteria comprised patients who finished their comprehensive orthodontic treatment based on a camouflage non-extraction modality using self-ligating orthodontic appliances therapy (SPEED brackets, Canada or Empower brackets, American Ortho, Sheboygan, WI, USA) or clear aligner therapy (Invisalign, Align Technology, San Jose, CA, USA). Patients were recruited from a university orthodontic clinic and a senior orthodontist's practice. The exclusion criteria comprised patients presenting with hypodontia, microdontia, severe periodontal problems, heavily resorted teeth and patients who were using retainers with occlusal coverage.Data analysis Included patients were assessed at three points in time: at the end of active orthodontic treatment and the start of retention phase (T0); at three months post treatment (T3); and at six months post treatment (T6). The following three assessments were done for each patient at T0, T3 and T6: a T-Scan 10 digital occlusal analysis recording into maximum intercuspation position (MIP); self-report about retainer compliance; and self-assessment of occlusal comfort using a visual analogue scale (VAS) ranging from 0-10 (0 = very uncomfortable; 10 = maximum comfort).The digital occlusal analysis was performed using a 100µ thin, flexible, horseshoe-shaped Mylar sensor (Novus HD sensor, Tekscan Inc, S. Boston, MA, USA). This sensor contains 1,370 active pressure sensing cells, known as sensels, arranged in a compact grid, shaped as a dental arch. The patients were given instructions on how to bite on the sensor. With the sensor still in the patient's mouth, three consecutive self-intercuspated closure-into-MIP registrations were recorded. If there was a need to repeat the procedure, one minute was given as a rest. If several recordings were done for the same patient in the same visit, the most consistency between the three consecutive intercuspations was used for analysis. In addition, the same sensor was used in T0, T3 and T6, unless the sensor shown excessive wear.The following outcomes were assessed using the digital occlusal analysis: 1) an estimate of occlusal contact surface area based on the activated sensels on the sensor at MIP; 2) the total surface of contacts and the area ratio between anterior (canine to canine) to posterior (premolar to second molar) contact surfaces; 3) the overall relative force distribution based on the by the position of the centre of force (COF); 4) the symmetry of contact distribution was expressed as the percentage of contacts on the right side to the left side (%R/L); and 5) the time-simultaneity of the closure into MIP contacts was calculated by the occlusion time measurement which is the duration between first contact and the time MIP was reached.Results In total, 39 patients were enrolled in the study. The self-ligating fixed appliance group included 25 patients (mean age 18.7 ± 5.2; 6 women, 19 men) while the clear aligner therapy group included 14 patients (mean age 20.6 ± 7.3; ten women, four men). Both groups were matched in terms of age, Angle's classification, symmetry, retention protocol and total number of bonded lingual wires or facial type. However, they were not matched in terms of sex, with more women in the aligner group (p = 0.007). Moreover, eight patients (four in each group) were excluded from the study later on due to a change in the retention protocol or a missed visit. The results showed that self-reported compliance with a Hawley retainer was not different between groups. Occlusal comfort was similar in both groups at treatment completion, with a median score of eight in both groups.The results showed that were no statistically significant differences between the two groups regarding all outcomes assessed using the digital occlusal analysis. Although the %R/L (normal range = 50% ± 5%) was not significantly different between both groups, neither treatment resulted in ideal occlusal balance (ie symmetry). Indeed, ten patients finished their treatment with subtle asymmetry (%R/L >50 ± 10%), especially in the self-ligating fixed appliance group (nine patients) showing side force differences (five right dominant, four left dominant) versus only one patient in the clear aligner group (left dominant).The COF moved posteriorly in both groups from T0 to T6, in parallel with a decreased ratio of anterior to posterior surface area. A statistically significant difference was observed in the anteroposterior position of COF between sexes, being more anterior in women at all times (p <0.002).Conclusions The quality of the occlusal contacts in MIP was comparable in both groups at T0, T3 and T6. Neither treatment resulted in an ideal occlusal balance (that is, symmetry). Ten patients finished their treatment with subtle occlusal force asymmetry (that is, asymmetric left-to-right side occlusal force distribution), especially in the self-ligating fixed appliance group. Most occlusal changes happened during the first three months of the retention phase, with more posterior contacts forces developing in both groups. In this study, female patients maintained more anterior COF when compared to male patients.

Impact of intraoral non-pharmacological non-surgical adjunctive interventions on orthodontically induced inflammatory root resorption in humans: A systematic review.

BACKGROUND: The current systematic review aimed to assess the impact of intraoral non-surgical non-pharmacological adjunctive interventions on orthodontically induced inflammatory root resorption (OIIRR). SEARCH METHODS: Search without restrictions was performed up to November 2020 in three electronic databases (Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE) for randomized controlled trials (RCTs), prospective and retrospective non-randomized studies. The ROB 2.0 tool was used to assess the quality of the included RCTs, and the ROBINS-I tool was applied to non-randomized clinical studies. The strength of evidence was ranked using GRADE. RESULTS: Three hundred and sixteen records were initially retrieved. A total of 10 studies, with 236 patients, were finally considered. These studies assessed the effects of mechanical vibration (low-frequency and high-frequency), low-intensity pulsed ultrasound (LIPUS), low-level laser therapy (LLLT) and photobiomodulation (light-emitting devices (LED). While the low-frequency vibration and LED do not seem to affect OIIRR, OIIRR has been reported to be reduced in high-frequency vibration, and LIPUS-treated teeth (differences may not likely be considered clinically relevant). The potential positive effect of LLLT on OIIRR is still debatable. Overall, the existing evidence suggests that the amount of OIIRR observed while using these interventions with traditional orthodontic treatment was not more than that was observed without it. CONCLUSIONS: Based on a very low level of confidence, it seems that intraoral non-pharmacological non-surgical adjunctive interventions do not affect the amount of OIIRR either positively or negatively to a clinically relevant degree when compared to what is seen with conventional orthodontic treatment alone.

Effects of Intraligamentary Injection of Osteogenic-Induced Gingival Fibroblasts on Cementum Thickness in the Dog Model of Tooth Root Resorption.

Tooth root resorption is an unwanted result of orthodontic tooth movement, and it can be expressed by a reduction in cementum thickness. The aim of this experimental study was to evaluate the effect of intraligamentary injection of osteogenic-induced gingival fibroblasts (OIGF) on cellular and acellular tooth root cementum thickness in modeled orthodontic tooth movement. Six beagle dogs were used in the study. All the upper and lower third and fourth premolars were subjected to mechanical loading for 4 weeks, which induced orthodontic tooth movement. Fifteen premolars were assigned to the OIGF group, which received a single OIGF injection through the periodontal ligament near the root apex (n = 7 teeth), and to the control group, which received a single injection of Dulbecco's modified eagle's medium in the periapical area (n = 8 teeth). The evaluation of histomorphometry was performed to assess the thicknesses of cellular and acellular cementum at the root apex and four bilateral sites distal to the apex. We found no statistically significant enhancing effects of gingival fibroblasts on either cellular or acellular cementum thicknesses when compared with the control group. We conclude that a single intraligamentary injection of OIGF does not stimulate the formation of tooth root cementum in the dog model of orthodontic tooth movement. Thus, OIGF is unlikely to prevent orthodontic-induced tooth root resorption.

Cone-beam Computed Tomography Analysis of the Relationship between the Curve of Spee and the Collum Angle of Mandibular Anterior Teeth.

AIMS AND OBJECTIVES: To evaluate the correlation between the curve of Spee (COS) of a patient and the Collum angle of mandibular anterior dentition using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: This cross-sectional study was based on the analysis of 100 CBCTs of patients divided sagittally into two separate subjects. The Collum angles of the mandibular central incisor, mandibular lateral incisor, and the mandibular canine were measured along with the COS of that quadrant using Dolphin Imaging. A multivariate linear regression and Pearson correlation coefficients were conducted to measure the correlation between the COS and the Collum angle of mandibular anterior dentition. RESULTS: The total number of participants in the cohort was 200 samples out of 100 patients as this was a split mouth study. The mean COS was 2.09 ± 1.239 mm. The mean Collum angle of the mandibular central incisor (L1) was found to be 6.50 ± 3.002 degrees. The mean Collum angle of the mandibular lateral incisor (L2) was 7.19 ± 2.554 degrees and the mean Collum angle of the mandibular canine (L3) was 7.03 ± 2.907 degrees. There was a statistically significant moderate correlation between L1, L2, and L3 and the COS with the Collum angle of the mandibular central incisor most highly correlated to the COS (0.42), followed by the mandibular lateral incisor (0.35) and then the mandibular canine (0.30). CONCLUSIONS: There is a statistically significant low to moderate correlation between the COS and the Collum angles of the mandibular anterior dentition.

Changes in Airway Dimensions Following Non-extraction Clear Aligner Therapy in Adult Patients with Mild-to-moderate Crowding.

AIM AND OBJECTIVE: This retrospective study aimed to assess changes in airway dimensions with non-extraction clear-aligner-therapy (NE-CAT) in adult patients with mild-to-moderate crowding. MATERIALS AND METHODS: Cone-beam computed tomographic images were evaluated for 24 adults (16 females and 8 males) with mild-to-moderate crowding, and Class I or mild skeletal Class II malocclusion before and after NE-CAT. Cross-sectional and volumetric airway measurements were performed at the level of the nasal cavity, upper pharyngeal airway space (UAS), and lower pharyngeal airway space (LAS). The Frankfort-mandibular plane angle (FMA), point A-nasion-point B (ANB) angle, and intermolar width were measured. A paired t-test was used to assess changes in airway measurements. Linear regression analyses were performed to identify predictors of the pharyngeal airway volume change at the levels of the UAS and LAS. RESULTS: There was a significant decrease (p = 0.004) in UAS mean volume (486.63± 752.73 mm3), LAS mean volume (p = 0.006), and cross-sectional airway area (p = 0.022) (1536.92± 2512.02 mm3 and 34.66± 69.35 mm2, respectively) with NE-CAT. The mean airway volume of the nasal cavity, mean cross-sectional airway areas of the nasal cavity and UAS, and mean minimum cross-sectional pharyngeal airway area did not change significantly with NE-CAT. Changes in pharyngeal airway volume were not significantly associated with patients' age, gender, treatment duration, pretreatment ANB angle, and changes in FMA and maxillary first intermolar width with NE-CAT. CONCLUSION: Significant changes in the pharyngeal airway dimensions of the UAS and LAS with NE-CAT in adult patients with mild-to-moderate crowding were identified. CLINICAL SIGNIFICANCE: The results of the present study show that NE-CAT is not associated with an improvement in airway dimensions in adults with mild to moderate crowding.

Do orthodontic fixed retainers guarantee the stability of dental alignment at the end of orthodontic treatment?

Data sources Electronic searches of studies on orthodontic retainers were conducted up to 12 February 2021 in four electronic databases including Scopus, Web of Science, Embase and PubMed. Only studies in English language were included.Study selection Only clinical studies were included. The inclusion and exclusion criteria were reported. The initial search identified 117 results. After removing duplicate studies, studies were evaluated against the inclusion criteria. Finally, 21 papers were included. Selection of the studies was performed independently by two reviewers. The included studies assessed the effects of the type of orthodontic wire or fibre splint, the material used to bond it to the teeth and the procedure for bonding on the failure rate of the fixed orthodontic retainers.Data extraction and synthesis Data extraction was performed independently by two reviewers. They followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. The following items were extracted: authors, year, type of study, study objective, number of subjects, comparison made, outcome measured and results. Three tools were used to assess the risk of bias of the included studies including the revised tool for assessing risk of bias in randomised trials (RoB 2), the Newcastle-Ottawa Scale for case-control studies and the Newcastle-Ottawa Quality Assessment Form for Cohort Studies. Meta-analysis was performed using the random-effects model.Results Twenty-one studies were included in the qualitative analysis while seven studies were included in the quantitative analysis. The included studies were three retrospective cohort studies, two case-controlled studies and 16 randomised clinical studies. The results showed that the failure rate of orthodontic fixed retainers ranged from 7.3% to 50%. Failure rates of fixed retainers placed in the maxilla were higher than those placed in the mandible. Previous failure increased the risk of repeat failure. Adhesive failure was considered the most common type of bond failure that was observed in fixed lingual retainers. The type of wire or splint has no effect on the failure rate. Results showed that retainers bonded to all teeth were more efficient in maintaining alignment when compared to retainers bonded on the teeth on the ends only. Indirect bonding techniques have no advantage over direct bonding techniques except for shorter chair time. Bonding fibre-reinforced composite retainers were more sensitive to operator skills, hence failure rates would be high if an incorrect technique was used when bonding.Conclusions No fixed retainer can guarantee the stability of alignment stability after orthodontic treatment. Retainers that are bonded to all teeth are preferable to those bonded only at the ends of the wire. Wires and fibre splints were similar regarding failure rates and stability of alignment.

Comparison of the Condyle Sagittal Position of Class I and Class II Division 2 in Orthodontic Patients.

AIM: To compare the condyle sagittal position of class I and class II division 2 in orthodontic patients. MATERIALS AND METHODS: Fifty orthodontic cases (30 females and 20 males; 12-31 years) from the records of an Orthodontic Graduate Program were collected. Such cases presented cone-beam computed tomography (CBCT) as part of their initial diagnostic examinations. The study sample constituted two groups, i.e. class I and class II division 2 groups. A previously calibrated examiner performed the measurements of the images, representing the distance between the condyle and the articular surface of the glenoid fossa, both anteriorly (anterior disk space-ADS) and posteriorly (posterior disk space-PDS). Descriptive statistics were performed. Data were normally distributed, and parametric tests were used. Paired sample test was used to identify differences between the right and the left joints. Differences between class I and class II/2 groups were tested using independent t test. All statistical tests were interpreted at 5% significance level. RESULTS: When the study groups were compared in relation to the dimensions observed for the right and the left ADS and PDS, no significant differences were detected. This study also calculated the differences between right and left disk spaces within the groups, and the differences were not significant for both class I and class II/2 groups. CONCLUSION: The results demonstrated, after the performance of a CBCT comparative analysis, that there is no significant difference between class II/2 and class I orthodontic patients in relation to the condyle sagittal position. CLINICAL SIGNIFICANCE: The results collected here refute the expectation of spontaneous mandibular anterior repositioning after correcting the overbite in class II/2 patients.

Effect of pulsed ultrasound toothbrush on Streptococcus mutans biofilm removal.

PURPOSE: To evaluate the effect of pulsed ultrasound toothbrush on the removal of biofilm formed by Streptococcus mutans (S. mutans). METHODS: S. mutans biofilm grown on apatite pellet was destructed with four different sonic action toothbrushes: 1) pulsed ultrasound with sonic vibration (PUV); 2) continuous ultrasound with sonic vibration (CUV); 3) sonic vibration only (SV); and 4) no ultrasound nor sonic vibration (control). After 3 minutes of noncontact brushing, the amount of water-insoluble glucan was measured, and the residual biofilm was observed by scanning electron microscopy. RESULTS: PUV group revealed the smallest amount of the residual water-insoluble glucans (32 ± 19%), followed by the CUV group (54 ± 12%) and the SV group (64 ± 13%). The PUV group showed a significantly lower amount of the residual water-insoluble glucan than the SV group, while no significant difference was found between SV and CUV. The bacterial adherence and aggregation notably decreased in the PUV group, compared to the remaining three groups. CLINICAL SIGNIFICANCE: The sonic vibration with pulsed ultrasound showed more reduction of the biofilm compared to the control and the sonic vibration with and without continuous ultrasound. Thus, pulsed ultrasound action may be beneficial for biofilm removal of interproximal regions.

Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study.

Background/objective: The aim of this study was to evaluate the efficacy of tooth alignment with conventional and self-ligating labial and lingual orthodontic bracket systems. Materials/methods: We tested labial brackets (0.022″ slot size) and lingual brackets (0.018″ slot size). The labial brackets were: (i) regular twin brackets (GAC-Twin [Dentsply]), (ii) passive self-ligating brackets including (Damon-Q® [ORMCO]; Ortho classic H4™ [Orthoclassic]; FLI®SL [RMO]), and (iii) active self-ligating brackets (GAC In-Ovation®C [DENTSPLY] and SPEED™[Strite]). The lingual brackets included (i) twin bracket systems (Incognito [3M] and Joy™ [Adenta]), (ii) passive self-ligating bracket system (GAC In-Ovation®LM™ [Dentsply]), and (iii) active self-ligating bracket system (Evolution SLT [Adenta]). The tested wires were Thermalloy-NiTi 0.013″ and 0.014″ (RMO). The archwires were tied to the regular twin brackets with stainless steel ligatures 0.010″ (RMO). The malocclusion simulated a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially). Results: The results showed that lingual brackets are less efficient in aligning teeth when compared with labial brackets in general. The vertical correction achieved by labial bracket systems ranged from 72 to 95 per cent with 13″ Thermalloy wires and from 70 to 87 per cent with 14″ Thermalloy wires. In contrast, the achieved corrections by lingual brackets with 13″ Thermalloy wires ranged between 25-44 per cent and 29-52 per cent for the 14" Thermalloy wires. The anteroposterior correction achieved by labial brackets ranged between 83 and 138 per cent for the 13″ Thermalloy and between 82 and 129 per cent for the 14″ Thermalloy wires. On the other hand, lingual brackets corrections ranged between 12 and 40 per cent for the 13″ Thermalloy wires and between 30 and 45 per cent for the 14″ Thermalloy wires. Limitation: This is a lab-based study with different labial and lingual bracket slot sizes (however they are the commonly used ones in clinical orthodontics) and study did not consider saliva, periodontal ligament, mastication and other oral functions. Conclusions: The effectiveness of lingual brackets in correcting vertical and anteroposterior displacement achieved during the initial alignment phase of orthodontic treatment is lower than that of the effectiveness of labial brackets.