Continuous Levodopa Delivery with an Intraoral Micropump System: An Open-Label Pharmacokinetics and Clinical Study.

BACKGROUND: Double-blind studies have demonstrated that motor complications in Parkinson's disease (PD) can be reduced with continuous delivery of levodopa. The DopaFuse system is a novel, intraoral micropump that attaches to a retainer and uses a propellant to deliver levodopa/carbidopa (LD/CD) continuously into the mouth. OBJECTIVES: Evaluate the safety, pharmacokinetics, and efficacy of LD/CD delivered via the DopaFuse system compared to treatment with intermittent doses of standard oral LD/CD in PD patients with motor fluctuations. METHODS: This was a 2-week, open-label study (NCT04778176) in 16 PD patients treated with ≥4 levodopa doses/day and experiencing motor fluctuations. On Day 1 (clinic setting) patients received their usual dose of standard LD/CD; DopaFuse therapy was initiated on Day 2, and on Day 3 patients received DopaFuse plus a morning oral LD/CD dose. Patients returned home on Days 4-14 and returned for in-clinic assessment on Day 15. RESULTS: Continuous DopaFuse delivery of LD/CD was associated with reduced variability in plasma levodopa levels compared to oral LD/CD (mean ± SD levodopa Fluctuation Index reduced from 2.15 ± 0.59 on Day1 to 1.50 ± 0.55 on Day 2 (P = 0.0129) and to 1.03 ± 0.53 on Day 3 (P < 0.0001)). This pharmacokinetic improvement translated into significantly reduced OFF time with DopaFuse therapy (reduction of -1.72 ± 0.37 h at Day 15; P = 0.0004) and increased ON time without severe dyskinesias (increase of 1.72 ± 0.37 h at Day 15; P = 0.0004) versus oral LD/CD administration. DopaFuse therapy was not associated with any clinically significant adverse events. CONCLUSIONS: Continuous delivery of LD/CD using the DopaFuse system was associated with significantly less variability in plasma levodopa concentrations and reductions in OFF time compared to treatment with standard oral LD/CD therapy and was well tolerated. © 2024 International Parkinson and Movement Disorder Society.

Stability and failure rate during 3 years of fixed retention: A follow-up of an randomized clinical trial on adolescents with four different lingual retainers.

OBJECTIVE: To evaluate stability outcomes and failure rates associated with four types of lingual retainers: (1) dead-soft wire, (2) multistrand stainless steel (SS) wire, (3) CAD/CAM nitinol, and (4) connected bonding pads (CBPs) after 3 years of retention. METHODS: This study enrolled 96 patients (66 females, 30 males) with a median age of 19 years with four types of lingual retainers: (1) 0.016 × 0.022-inch dead-soft wire, (2) 0.0215-inch five-strand SS wire, (3) 0.014 × 0.014-inch CAD/CAM nitinol wire, and (4) CBPs. The irregularity index, intercanine distances, and arch lengths were obtained and used to evaluate mandibular stability. Failure rates were also assessed during this study. Data were statistically analysed. RESULTS: Irregularity increased, whereas intercanine width and arch length decreased after 3 years of retention. The greatest irregularity was associated with the CBPs and the least with the CAD/CAM retainers. Changes in stability measurements were significantly higher in the dead-soft wire and CBPs than those in the CAD/CAM nitinol and multistrand SS wires. Parallel to these changes, the frequency of failure yielded similar results with the same significance between the groups. The failure rate of CBPs, in contrast to the CAD/CAM nitinol and multistrand SS wires, was significantly higher in the right quadrant (P < .05). CONCLUSION: After taking the 3-year results into consideration, CAD/CAM nitinol and multistrand SS wires were found to be more successful than the others in maintaining mandibular stability. The most failures were observed with CBPs after 3 years of retention.

Retention efficacy and patient experience with customized clear retainer and wrap-around circumferential retainer among non-extraction orthodontic patients: A 12-month follow-up cohort study.

OBJECTIVE: The aim of this study was to evaluate retention efficacy by assessing retention stability and patient perspectives according to type of circumferential retainer: the wrap-around circumferential retainer (WCR) and customized clear retainer (CCR). MATERIALS AND METHODS: This cohort follow-up study involved 52 patients aged 18-62 who underwent fixed-appliance orthodontic treatment without extractions or orthognathic surgery. Following screening consenting participants were divided into WCR and CCR groups. All participants before follow-up received fixed retainers for the upper and lower anteriors and respective removable retainers within 2 weeks post-debond. Intraoral scans and lateral cephalograms were taken immediately after debonding (T0) and again 12 months later. Dentoalveolar changes in several measurements were compared to evaluate retention efficacy. Surveys were conducted at 1 month (T1) and 12 months (T2) post-debonding to assess changes in patient experiences. Outcome assessments were blinded. Paired T-tests and independent T-tests were used for intragroup and intergroup comparisons of dentoalveolar measurements, respectively. Survey responses were analysed using the Pearson Chi-Square test. RESULTS: The final assessment included 32 participants. Model analysis revealed no significant differences between the groups, except for maxillary intermolar width (p = .033). In the WCR group, the cephalometric analysis indicated a significant increase in the incisor mandibular plane angle (p = .002) and a decrease in the interincisal angle (p = .014), while changes in the CCR group were statistically non-significant. Patient attitude evaluation showed similar trends for wear time and overall satisfaction. However, a higher percentage of respondents in the WCR group reported irritation when wearing the retainers (p = .037) at T1 and discomfort related to speech (p = .038) at T2. CONCLUSIONS: CCR showed better retention efficacy in terms of lower incisor inclination. Patients experienced relatively less irritation and speech discomfort with CCRs.

Efficacy and safety of a self-expandable retainer in endoscopic ear surgery.

PURPOSE: During endoscopic ear surgery (EES), it is important to maintain a clear view of the endoscopic camera to achieve a clean field. In this study, a self-expandable external auditory canal (EAC) retainer was developed to enable a more efficient and safer EES. This study aimed to evaluate the retainer's efficacy and safety in EES. METHODS: Among adult patients scheduled for endoscopic tympanoplasty, 50 participants were recruited. They were assigned to either the retainer or control group in a 1:1 ratio. The anatomical characteristics, number of endoscopic cleanings during surgery, surgeon's satisfaction, and other factors were evaluated. RESULTS: No differences were observed in the surgical direction, EAC size measured on preoperative temporal bone computed tomography scans, location and size of tympanic membrane perforation, or bleeding degree between the two groups. When comparing the surgical time, including retainer insertion and removal, the time was similar between groups (retainer group, 35 min; control group, 33.2 min). The frequency of endoscopic cleaning per minute was statistically significantly lower in the retainer group than in the control group (0.18 times per minute, p = 0.048). No side effects, including sensory abnormalities or allergic reactions, were reported in any patient who used the retainer. CONCLUSION: A reduction in unnecessary endoscopic cleaning during EES was observed while using the self-expandable retainer, leading to increased surgeon satisfaction and efficiency. Furthermore, as a safe method without side effects, the retainer could be widely used to various indications for EES beyond tympanoplasty.

Comparison of efficacy of thermoplastic retainer with round and rectangular bonded lingual wire retainer in the mandible two years after orthodontic treatment: a randomised controlled trial.

OBJECTIVE: To analyse three protocols in maintaining the stability of orthodontic therapy results and their effect on gingival health. MATERIALS AND METHODS: Sixty-six subjects (pre-therapeutic age 11-18 years; 68% female) randomly allocated into three retention groups of equal size were analysed. The first group had a 0.673 × 0.268 mm (0.027 × 0.011 inches) rectangular braided steel retention wire bonded to the lingual surfaces of all mandibular teeth from canine to canine, and the second group had a 0.406 mm (0.016 inches) round twisted steel wire. The third group was the control, without wires, and only with vacuum-formed retainers. All three groups had vacuum-formed removable retainers in the maxilla. The frequency of wire detachment/breakage/loss of retainer, the occurrence of crowding of mandibular incisors, and changes in intercanine width and gingival health were monitored. RESULTS: Incidence and severity of relapse differed between groups (p = 0.001 and 0.049) being most common in the removable retainer group (incidence 68.2%; severity 0.7 ± 1.0 mm), followed by the round wire group (36.4%; 0.5 ± 1.2 mm) and rectangular wire group (13.6%; 0.1 ± 0.1 mm). The intercanine width decreased more without a bonded retainer (incidence 68.2%; severity 0.5 ± 0.7 mm) and with the round wire more (45.5%; 0.5 ± 0.7 mm) than with the rectangular (27.3%; 0.1 ± 0.3 mm). The difference was significant for incidence (p = 0.025), but not severity. Detaching of the wires/breakage/loss of retainer was similar. There were no significant differences in the accumulation of biofilm, calculus and gingivitis between appliances. CONCLUSION: A rectangular wire is the most effective in retention, and the impact of retention appliances on gingival health is similar. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05121220. Registered 02 October 2021 - Retrospectively registered. CLINICAL RELEVANCE: Studying guidelines for reducing relapse, proper use of materials and appliances, the behavior of retention wires according to their profile in the retention phase, and possibilities of maintaining oral health will contribute to improving the stability of orthodontic therapy results.

Gingival health and relapse tendency: a split mouth randomized controlled trial of two positions of lower fixed retainers.

OBJECTIVE: To compare between lower permanent retainers placed in the middle of the incisal third and retainers placed in the middle of lower incisors in terms of gingival condition, lower incisors stability and retainers' failure rate. MATERIALS AND METHODS: This is a split-mouth clinical trial. Fifty patients finished fixed orthodontic treatment and required fixed permanent retainer in the lower arch were recruited. A multistranded (0.0215 inch) retainer, with a vertical step in the midline placing half of the retainer in the incisal third and the other half in the middle of the lower incisors was attached to all the teeth in the lower labial segment. After one year, all the subjects were recalled. The primary outcome was to evaluate the plaque index (PI) and the gingival index (GI) of the lower labial segment teeth. The secondary outcome was to assess retainers' failure rate and the relapse in lower labial segment alignment. RESULTS: The GI and the PI scores were significantly smaller on the side where the retainer was placed incisally (P = 0.004, P < 0.001, respectively). There was no statistical difference in the average Irregularity Index (IRI) and the retainer's failure rate between the two sides (P = 0.52, P = 0.76, respectively). CONCLUSION: Placing lower fixed retainers in the incisal third will improve the lower labial segment oral hygiene and gingival health in the lingual area without affecting the efficiency or the integrity of the retainers. This trial was not registered Null Hypothesis: Placing the lower permanent retainer in the middle of the lingual surfaces of the lower labial segment' teeth or in the incisal third will not affect the gingival health of the lower incisors.

Can vacuum-formed retainers maintain arch dimensions and alignment compared to Hawley and fixed bonded retainers after treatment with fixed appliances? A systematic review and meta-analysis.

BACKGROUND: Different types of retention appliances have been proposed over the years, but their effectiveness in maintaining arch dimensions and alignment after orthodontic treatment is still unclear. AIM: To assess the efficacy of vacuum-formed retainers (VFRs) in preserving arch widths, arch length, and anterior alignment in maxillary and mandibular arches, compared to removable Hawley retainers (HRs) or fixed bonded retainers (FBRs). Search methods: unrestricted literature search of five major databases up to March 2024. SELECTION CRITERIA: randomized/non-randomized clinical studies comparing VFRs to removable HRs or FBRs. DATA COLLECTION AND ANALYSIS: after duplicate study selection, data extraction, and risk of bias assessment, random effects meta-analyses of standardized mean differences and their 95% confidence intervals were performed, followed by meta-regressions, sensitivity analyses, and assessment of the quality of evidence with GRADE. RESULTS: Twenty-two prospective studies (4 non-randomized and 18 randomized controlled trials) involving 1797 patients (mean age 17.01 years, 38.3% males) were included. No significant differences were found in the intercanine width, intermolar width, and arch length between VFRs and HRs, in both arches (P > 0.05). However, VFRs were statistically more effective than HRs in terms of Little's irregularity scores (LII) in the maxilla (eight studies; SMD = -0.42; 95% CI: -1.03 to -0.09; P = 0.02; I2 = 73.4%) but not in the mandible (P = 0.12). No significant differences were reported for all considered outcomes between VFRs and FBRs in in both arches (P > 0.05), except for lower LII, where VFRs were significantly less efficient (eight studies; SMD = 1.49; 95% CI = 0.26-2.7; P = 0.02; I2 = 93%). Follow-up times, risk of bias, and wire type (of FBRs) did not show statistically significant effects on outcome variables. Sensitivity analyses showed robustness of the findings for including non-randomized and postretention studies. The certainty in these estimates was from moderate to low due to the risk of bias and inconsistency. CONCLUSIONS: Low to moderate quality evidence indicates that VFRs are as effective as HRs in maintaining arch widths, length, and alignment. Low-quality evidence found similar efficacy between VFRs and FBRs, with FBRs being statistically more effective at maintaining lower arch alignment, but the difference was not clinically significant. REGISTRATION: PROSPERO registration (CRD42024518433).

Poly-ether-ether-ketone (PEEK) versus dead-soft coaxial bonded retainers: a randomized clinical trial. Part 1. Stability, retainer failure, and participant satisfaction.

BACKGROUND: Poly-ether-ether-ketone (PEEK) was introduced in dentistry as an alternative to metal alloys. OBJECTIVE: To assess the effectiveness of PEEK-fixed retainers in preserving the stability of mandibular anterior and participant satisfaction as compared to the Dead-soft coaxial fixed retainer (DSC). TRIAL DESIGN: A single-centre, two-arm parallel groups randomized clinical trial. METHODS: The patients treated with pre-adjusted orthodontic appliances who have a Little's Irregularity Index (LII) ≤ 0.5 mm have been enrolled in the trial. PEEK retainers were prepared to round 0.8 mm wire by computer-aided design and manufacturing, and the DSC wire was carefully adapted to the lingual surface of the lower anterior teeth. The primary outcome was the stability of lower anterior teeth as assessed by LII, while the secondary outcomes were changes in occlusal parameters, retainer failure, and patient satisfaction. The data were collected at the debonding stage (T0), 1 month (T1), 3 months (T3), and 6 months (T6) after starting the trial, except for patient's satisfaction, which was recorded using an electronic form at T1 and T6. BLINDING: Single blinding of participants. RESULTS: A total of 46 participants with an age range of 12-28 years old were randomly allocated to the two groups (n = 23 in each). Only one participant dropped out; therefore, 45 participants were analysed. The DSC group showed a significant increase in LII at T3. Both retainer groups had comparable occlusal measurements, failure frequency, and survival time, with no significant difference. The patients in the DSC group reported a statistically significant perception of change in the position of their teeth compared to those in the PEEK group. HARMS: No harmful effects have been reported. LIMITATIONS: Limited follow-up duration and the inability to blind the operator due to the nature of the intervention. CONCLUSIONS: After 6-month retention, the PEEK retainer was equally effective to DSC retainers in maintaining the teeth alignment, with no significant differences regarding the failure frequency, survival rate, and general patient satisfaction. TRIAL REGISTRATION: https://register.clinicaltrials.gov. (NCT05557136).

Poly-Ether-Ether-Ketone versus dead-soft coaxial bonded retainers: a randomized clinical trial. Part 2: periodontal health and microbial biofilm assessment.

BACKGROUND: Retainers have the potential to detrimentally impact periodontal health and contribute to tooth decay. OBJECTIVES: To investigate periodontal health and bacterial biofilm related to Poly-Ether-Ether-Ketone (PEEK) fixed retainers as compared to Dead-soft coaxial fixed retainer (DSC). TRIAL DESIGN: A two-arm parallel groups single-centre randomized clinical trial. METHODS: The trial included patients whose orthodontic treatment was completed and required retainers. Participants were randomly assigned into two retainer groups: PEEK retainers, prepared by computer-aided design and manufacturing into 0.8 mm wire form, and DSC retainers. The objectives included assessing periodontal health through plaque accumulation index (PI), bleeding on probing (BOP), periodontal pocket depth (PPD), gingival index (GI), calculus index (CI), and alveolar bone height (ABH) assessment. Biofilm assessment involved bacteriological screening of aerobic, facultative anaerobic, mutans streptococci, and lactobacilli. The periodontal indices and microbiological screening as well as were assessed at the debonding stage (T0), 1-month (T1), 3-month (T3), and 6-month (T6) after the commencement of the trial, except for the ABH, which was recorded using periapical radiograph at T0 and T6. BLINDING: Single blinding of participants in addition to the bacteriological specialist. RESULTS: Initially, the trial enrolled 46 participants, aged between 12 and 28 years, and were randomly assigned to two groups, with 23 participants in each group. Subsequently, one participant withdrew from the trial, resulting in a total of 45 participants whose data were analysed. Assessment of the periodontal indices, excluding the CI (P = .480), revealed statistically but not clinically significant differences between groups after 6-month of retention (P = .016 of PI, P = .020 of BOP, P = .05 of PPD, and P = .01 of GI). There was slight plaque accumulation, normal PPD (approximately 1 mm), healthy to mild gingivitis with a GI of less than 1 and BOP was around 10%. Concerning the ABH, there was a noticeable reduction in its score after 6 months, particularly in the PEEK group, although the difference was not statistically significant (P = .102). Furthermore, the bacteriological viable count did not show any significant difference between the groups during the recall visits. HARMS: There have been no reported negative consequences. LIMITATIONS: Blinding the assessor of periodontal indices was not feasible due to the nature of the intervention. The trial follow-up duration was limited. CONCLUSIONS: Both the PEEK and DSC retainers have comparable impacts on periodontal health and bacterial accumulation and composition during the retention period. TRIAL REGISTRATION: NCT05557136.

Influence of fixed orthodontic steel retainers on gingival health and recessions of mandibular anterior teeth in an intact periodontium - a randomized, clinical controlled trial.

OBJECTIVE: Aim of this randomized clinical controlled trial was to evaluate the influence of fixed orthodontic steel retainers on gingival health and recessions of mandibular anterior teeth. MATERIALS AND METHODS: After end of the orthodontic treatment, patients were randomly assigned into the test (fixed steel retainer) or control group (modified removable vacuum-formed retainer). Periodontal parameters (periodontal probing depth: PPD; recession: REC; bleeding on probing: BOP) as well as plaque and gingival index were assessed on mandibular anterior teeth directly before attaching/handing over the retainer (baseline: BL), 6 and 12 months after orthodontic treatment. RESULTS: 37 patients (test: n = 15, mean age: 16.1±4.2 years; control: n = 17, mean age: 17.1±5.4 years) completed the study. REC and PPD failed to show significant pairwise differences. The number of patients showing gingival health in the area of the mandibular anterior teeth (test: BL n = 10, 6 months n = 9, 12 months n = 11; control: BL n = 10, 6 months n = 16, 12 months n = 15) revealed a significant difference for the intra-group comparison between BL and 6 months in the control group (p = 0.043). The inter-group comparisons failed to show significant differences. CONCLUSION: Young orthodontically treated patients with fixed steel retainers show in 73.3% healthy gingival conditions after one year which are comparable to the control group (88.2%). Gingival recessions were in a clinically non-relevant range at any time of the examination. CLINICAL TRIAL NUMBER: DRKS00016710.

Mechanical properties of combined packable and high-filled flowable composite used for the fixed retainer: an in vitro study.

BACKGROUND: Clinicians often utilize both flowable and packable composites concurrently in bonding fixed retainers. Thus, this study aimed to assess the synergistic effect of these composites in the bonding process. METHODS: This in vitro study divided specimens into three groups: flowable composite (nano-hybrid, Tetric N-Flow, Ivoclar Vivadent), packable composite (nano-hybrid, Tetric N-ceram, Ivoclar Vivadent), and combined use of flowable and packable composite. Shear bond strength (SBS), adhesive remnant index (ARI), and wire pull-out resistance were compared among the groups. Statistical analyses were conducted using ANOVA and Tukey tests to compare study groups. Additionally, Chi-square and Kruskal-Wallis tests were employed to analyze the ARI index among the groups. RESULTS: ANOVA results indicated no statistically significant differences among test groups (P = 0.129) regarding SBS. However, a significant difference existed between flowable and packable composite groups (P = 0.01) regarding ARI scores. Among the study groups, flowable composite exhibited the highest frequencies of ARI scores of 1 and 2, whereas packable composite showed the highest frequency of ARI scores of 0. The combined group had higher frequencies of ARI scores of 0 and 1 compared to the flowable composite. The wire pull-out test revealed that the combined application of flowable and packable composite resulted in significantly lower detachments compared to the packable composite alone (P = 0.008). However, no significant differences were observed in the comparisons between the flowable-packable (P = 0.522) and combined-flowable (P = 0.128) groups. CONCLUSION: The combined use of flowable and packable composites for fixed retainers demonstrated adequate shear bond strength and ideal ARI scores, suggesting it as a suitable adhesive system for bonding orthodontic fixed retainers.

Post-treatment stability, survival time and periodontal health associated with vacuum-formed, bonded and rapid prototype retainers: A prospective clinical study.

BACKGROUND: New technologies have paved the way for newer fabrication techniques, such as rapid prototyping, which has gained popularity in the fabrication of several orthodontic appliances including retainers. AIM: To evaluate the stability, survival time and periodontal health associated with vacuum-formed retainers (VFRs), bonded retainers (BRs) and rapid prototype retainers (RPRs) over a period of 12 months in retention. STUDY DESIGN: Prospective clinical study. METHODS: A total of 72 participants completing fixed orthodontic treatment were allocated to the following three groups by the investigators based upon their initial malocclusion, compliant and preferences: VFR; BR; and RPR. The primary outcome was Little's Irregularity Index (LII). Other stability parameters, including arch length (AL), inter-canine width (ICW) and inter-molar width (IMW), were also assessed immediately after debonding (T0) and 12 months (T2) after debonding. In addition, survival time, and calculus index and gingival index (GI) were assessed. RESULTS: LII showed a significant difference (P = 0.00) between the groups and was increased in the VFR group (0.18 ± 0.22 mm) compared to the BR (0.03 ± 0.05 mm) and RPR (0.01 ± 0.03 mm) groups but was not clinically significant. The mean survival time of maxillary retainers was longest for the RPR group (220.63 days; 95% confidence interval [CI] = 194.1-247.16) but there was no significant difference between the three groups (P = 0.43). The mean survival time of mandibular retainers was higher and the same for the VFR and RPR groups (240 days; 95% CI = 240-240) and there was no significant difference between the three groups (P = 0.38). The calculus index score (P = 0.00) was statistically significant between the groups, with an increased score for the BR group (0.33 ± 0.27) compared to the VFR (0.07 ± 0.16) and RPR (0.13 ± 0.22) groups. Similarly, the GI score (P = 0.02) was statistically significant between the groups and was increased in the BR group (0.01 ± 0.19) compared to the VFR (-0.15 ± 0.18) and RPR (-0.06 ± 0.15) groups. The increase in calculus index and GI scores for the BR group were not clinically significant. CONCLUSION: There were no clinically significant differences between the three retainer groups in terms of stability, periodontal health and time to failure.

CAD/CAM-BASED FIXED LINGUAL ORTHODONTIC RETAINERS MAY BE AS EFFECTIVE AS CONVENTIONAL FIXED RETAINERS.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Bardideh E, Ghorbani M, Shafaee H, Saeedi P, Younessian F. A comparison of CAD/CAM- based fixed retainers versus conventional fixed retainers in orthodontic patients: a systematic review and network meta-analysis. Eur J Orthod. 2023 Sep 18;45(5):545-557. doi:10.1093/ejo/cjad033. PMID: 37471113. SOURCE OF FUNDING: The study was not funded. TYPE OF STUDY/DESIGN: Systematic review with network meta-analysis.

Single-retainer all-ceramic resin-bonded fixed dental prostheses: Long-term outcomes in the esthetic zone.

OBJECTIVES: To present an update on the concept of cantilevered single-retainer all-ceramic resin-bonded fixed dental prostheses (RBFDPs) first presented 25 years ago in the Journal of Esthetic Dentistry. OVERVIEW: The initially presented case of the concept was followed clinically over 26 years and is presented along with two additional clinical long-term cases using varying methods to obtain an esthetic and hygienic ovate pontic design. Veneered alumina and zirconia ceramic (3 mol% yttria-tetragonal zirconia polycrystalline ceramic; 3Y-TZP) was used and bonded with a phosphate monomer containing luting resin after 50 µm alumina particle air-abrasion at 0.25 MPa pressure. The restorations replacing incisors did not debond and soft tissues in the pontic area were maintained over 26 years. CONCLUSIONS: Cantilevered single-retainer all-ceramic RBFDPs today made from veneered 3Y-TZP zirconia ceramic can be considered a standard of care for the replacement of single incisors and provide an excellent esthetic outcome with a long-term preservation of soft tissues in the pontic area. CLINICAL SIGNIFICANCE: Bonding nonretentive oxides ceramics such as alumina and zirconia ceramic with phosphate monomer containing luting resins after alumina particle air-abrasion is durable over decades. This proves that bonding to zirconia ceramic is not of any problem when adequate methods are used. Single-retainer zirconia ceramic RBFDPs maintain soft tissues in the edentulous area of single missing incisors and often deem implants unessential for this indication.

A comparative study of CAD/CAM fabricated polyether ether ketone and fiber-glass reinforcement composites versus metal lingual retainers under vertical load (an in vitro study).

BACKGROUND: Retainer is a necessary procedure when orthodontic treatment complete to avoid relapse due to periodontal fiber elasticity and to allow for alveolar bone regeneration. Compare the influence of vertical force on the failure of three fixed retainers: CAD/CAM polyether ether ketone (PEEK), CAD/CAM fiber glass reinforced composites (FRCs), and lingual retainer wire "Bond-A-Braid™". MATERIALS AND METHODS: One hundred and eight maxillary first premolars teeth were randomly allocated to three groups: Group A (CAD/CAM PEEK), Group B (CAD/CAM FRC), and Group C (lingual retainer wire " Bond-A-Braid™"). These retainers were bonded using Assure Plus Bonding Resin and GO TO Paste. For each specimen, a loading cycling and thermocycling machine was used. The failure debonding forces were measured on the interproximal segments using a universal testing machine with a cross-head speed of 1 mm/min. The adhesive remnant index (ARI) was calculated after identifying types of failure with a stereomicroscope at (X 20) magnification. RESULTS: Group B and group C showed the highest failure bonding forces, with a mean of 209.67 ± 16.15 and 86.81 ± 4.59 N, respectively. However, Group A had a statistically significant lower bond failure force, with a mean value of 45.73 ± 4.48 N. At baseline, there was a statistically significant difference in connector retainer displacement between the three studied groups (p < .001). The ARI score was not statistically significant (p < .001) between the three study groups; for groups A and B, the ARI was predominantly score 3, and group C showed a mixed score of 2 and 3. The failure mode of retainers was investigated using an optical stereomicroscope. In group B, there was a cohesive breakdown in the retainer, and groups A and C exhibited failures primarily in the adhesive at the retainer interface. CONCLUSION: All groups differed significantly, with group A having the lowest debonding force and group B having the highest. Furthermore, there was not a substantial variation in ARI, but there was a significant difference in connector retainer displacement and the types of failure amongst the three groups.

Simplifying placement of bonded retainers.

The placement of bonded retainers can be daunting to the inexperienced clinician. The aim of the present article was to share a simple means of using everyday intermaxillay elastics to effortlessly secure the wire, allowing the clinician to easily complete placement of the bonded retainer. The challenge of manipulating the wire, etch, bond and composite simultaneously is thus alleviated! A step-by-step explanation is provided.

Effect of self-etch primer application on the bond failure rate of a mandibular bonded lingual retainer.

BACKGROUND: The aim of this study was to examine the effect of self-etch primer (SEP) application on the bond failure rate of a mandibular bonded lingual retainer over 24 months. METHODS: The average age of the 86 individuals included in this study was 17 years 4 months. After the removal of the orthodontic appliances, the lingual retainers, which were made of six-stranded stainless steel wire, were bent and bonded onto the lingual surface of all mandibular anterior teeth. The study was performed using a split-mouth design. In the study group, the SEP was administered to the teeth's lingual surfaces. In the control group, they were etched using 37% phosphoric etchant liquid gel. After etching, the primer was applied. The adhesive resin was applied and the retainer was fitted. The patients were re-evaluated over 24 months. The first bond failures and the amount of adhesive remaining on the tooth were recorded as the adhesive remnant index (ARI) scores. The chi-square test was used to compare the bond failure rates (P = 0.231) and ARI scores between the groups (P = 0.162). The survival rates of the retainers were estimated using the Kaplan-Meier test (P = 0.237). The significance level was P < 0.05. RESULTS: The bond failure rates, ARI scores, and survival rates did not differ significantly between the groups. CONCLUSIONS: The results of this study demonstrated that an SEP can be used successfully in mandibular lingual retainer bonding. In situations where saliva isolation is difficult, bonding a fixed lingual retainer with SEP is recommended.

Comparing the effects of CAD/CAM nickel-titanium lingual retainers on teeth stability and periodontal health with conventional fixed and removable retainers: A randomized clinical trial.

OBJECTIVE: The objectives of this study were to evaluate the effect of a CAD/CAM nickel-titanium retainer on the stability of mandibular anterior teeth and periodontal health and to compare it with other retainers. SETTING/SAMPLE POPULATION: Sixty participants from both genders who had irregularities prior to orthodontic therapy and who had been treated with full-fixed appliance mechanotherapy were included in the study and randomly allocated into four groups: CAD/CAM NiTi, multi-stranded stainless steel, single-stranded nickel-free titanium and vacuum-formed removable retainer groups. The mean age of the participants at the end of the treatment was approximately 20 years. MATERIALS AND METHODS: Digital impressions were taken for all participants at three different times: immediately (T0 ), three months (T1 ) and six months (T2 ) after treatment. Irregularity index, inter-canine and inter-molar width, and arch length were recorded using software. Additionally, a full periodontal assessment was carried out at T2 . RESULTS: During the follow-ups, all groups showed some relapse in the lower anterior teeth. No statistical significance was found intergroup in terms of all measured values. Within the multi-stranded group, inter-canine width had decreased by 0.10 mm with a statistical significance (P = .048). An additional statistical significance with P = .045 was found within the single-stranded group regarding the increased arch length. The periodontal assessment results of the mandibular anterior teeth between groups did not show clinically significant differences. CONCLUSION: No statistical significance was found between the CAD/CAM retainer and other retainers regarding the clinical failure rate. Less plaque accumulation and gingival inflammation were observed in the CAD/CAM NiTi retainer group.

Evaluation of magnetic resonance imaging artifacts caused by fixed orthodontic CAD/CAM retainers-an in vitro study.

OBJECTIVES: Magnetic resonance imaging (MRI) image quality can be severely impaired by artifacts caused by fixed orthodontic retainers. In clinical practice, there is a trend towards using computer-aided design/computer-aided manufacturing (CAD/CAM) retainers. This study aimed to quantify MRI artifacts produced by these novel CAD/CAM retainers. MATERIAL AND METHODS: Three CAD/CAM retainers and a stainless-steel retainer ("Twistflex"; clinical reference standard) were scanned in vitro at 3-T MRI using a high-resolution 3D sequence. The artifact diameters and three-dimensional artifact volumes (AV) were determined for all mandibular (AVmand) and maxillary (AVmax) retainers. Moreover, the corresponding ratio of artifact volume to retainer volume (AV/RVmand, AV/RVmax) was calculated. RESULTS: Twistflex caused large artifact volumes (AVmand: 13530 mm3; AVmax: 15642 mm3; AV/RVmand: 2602; AV/RVmax: 2235). By contrast, artifact volumes for CAD/CAM retainers were substantially smaller: whereas artifact volumes for cobalt-chromium retainers were moderate (381 mm3; 394 mm3; 39; 31), grade-5 titanium (110 mm3; 126 mm3; 12; 12) and nickel-titanium (54 mm3; 78 mm3; 12; 14) both produced very small artifact volumes. CONCLUSION: All CAD/CAM retainers caused substantially smaller volumes of MRI artifacts compared to Twistflex. Grade-5 titanium and nickel-titanium CAD/CAM retainers showed the smallest artifact volumes. CLINICAL RELEVANCE: CAD/CAM retainers made from titanium or nickel-titanium may not relevantly impair image quality in head/neck and dental MRI. Artifacts caused by cobalt-chromium CAD/CAM retainers may mask nearby dental/periodontal structures. In contrast, the large artifacts caused by Twistflex are likely to severely impair diagnosis of oral and adjacent pathologies.

Computerized Assessment of Occlusion and Muscle Activity during Use of a Multilayer Clear Retainer: A Preliminary Study.

The aim of this preliminary study was to evaluate the short-term changes of occlusal contacts and muscle activity after orthodontic treatment during the use of a multi-layer clear retainer. Evaluation was done with the T-scan and BioEMG systems. A total of 18 subjects were included, who were evaluated at three time intervals-T0 at debonding, T1 at one month after retainer delivery, and T2 at four months after retainer delivery. The T-scan and electromyography (EMG) data were recorded simultaneously. The T-scan system recorded the occlusion time, disclusion time and force distribution. The EMG waves were quantified by calculating the asymmetry index and activity index. The time variables changed but not significantly. Occlusal force decreased in the anterior dentition and increased in the posterior dentition during T0-T2. There was no clear evidence of a relationship between unbalanced occlusal forces and muscle activity. In most subjects, the temporalis anterior muscle was more dominant than the masseter muscle. From this preliminary computerized study, there were no significant changes in the state of the occlusion or muscle activity during the short-term retention period.