Upper bonded retainers

Three-dimensional analysis of posttreatment tooth movements despite bonded retainers: part I-upper jaw

PURPOSE

Adverse side effects of fixed retainers in terms of unwanted tooth movements have been described for both the upper and lower jaw, but data about the extent and movement patterns for the maxilla are scarce. The purpose of the present retrospective case-control study was to analyze the amount and direction of unwanted tooth movements despite upper bonded retainers as well as to analyze possible predisposing pretreatment- and treatment-related factors.

METHODS

Plaster casts of 1026 patients who completed orthodontic treatment and a subsequent retention phase of 2 years were screened for unintentional tooth movements. The study group comprised 57 patients with visually obvious tooth movements in the upper jaw, while 57 randomly selected patients without visible tooth movements served as control group. For all patients, plaster casts after debonding of multibracket appliance (T1) and after supervised retention (T2) were digitized, and superimposed digitally using a stable palatal reference area. Thereafter, translational and rotational movements were measured in all three planes of space. Pretreatment- and treatment-related factors of the study and control groups were compared by χ2 test, exact Fisher test, Mann-Whitney U test, and the T‑test for independent samples.

RESULTS

The mean translational movements ranged between 0 and 0.6 mm and the average rotational movements between 0 and 1.3°. Large individual movements up to 2.7 mm translation and 15.9° rotation were seen. A movement pattern around the Y‑ and Z‑axis with an opposite rotational peak at the canines ("upper twist effect") was identified. Compared to the control group, patients of the study group showed a significantly smaller intercanine width pretreatment. Also, study group patients presented a larger intercanine expansion and a slightly larger overjet reduction during treatment, and were more often affected by retainer bonding site detachments and wire fractures, but without reaching statistically significance.

CONCLUSION

Upper bonded retainers show a similar unwanted movement pattern ("twist effect") like the one described for mandibular retainers.

The Micromechanical Properties and Surface Roughness of Orthodontic Retainer Wires-An In Vitro Analysis

BACKGROUND

Despite the large variety of retainer wires available, no studies could be found comparing the micromechanical properties and surface roughness of different retainer wires. Such characteristics affect the survival of the fixed retainer in terms of both fracture resistance and resistance to debonding from the tooth. Therefore, the aim of the present study was to examine and compare those characteristics in popular retainer wires.

METHODS

six different popular orthodontic retainer wires were subjected to instrumental indentation based on the Oliver and Pharr method. The geometric surface structure was analysed using a non-contact profilometer.

RESULTS

stainless steel wires had a higher hardness and a higher elastic modulus compared to titanium wires and white gold chain. The titanium wire and the white gold chain showed much more roughness than other wires.

CONCLUSIONS

stainless steel wires are the most resistant, considering both the shape retention capacity and the ability to resist abrasive wear. The titanium wire showed the lowest hardness and, thus, the highest susceptibility to deformation. Bond-a-braid, Retainium and Orthoflex white gold are more resistant to fracture than other steel wires. Titanium wire and chain retainer wires have more roughness, which is a great advantage in terms of mechanical adhesion to composite materials.

Impact of fixed orthodontic retainers on oral health-related quality of life: a longitudinal prospective study

OBJECTIVE

The aim of the present study was to assess the impact of orthodontic retainers on oral health-related quality of life (OHRQoL) in the short and long terms after orthodontic treatment.

METHODS

Data from 45 patients up to three years after orthodontic treatment (T0) were analyzed. Patients were reassessed four years (T1) after T0. OHRQoL was measured using the OHIP-14 (Oral Health Impact Profile-14) questionnaire. The presence of a fixed retainer in the upper and/or lower arches, sex, and age were the predictive variables evaluated at T0 and T1. The occurrence of retainer fracture at T0 was clinically evaluated. Due to the COVID-19 pandemic, clinical examination on T1 was not possible, so the OHIP-14 and the self-perception of changes in teeth position and fracture of retainers were examined using an on-line questionnaire.

RESULTS

At the initial examination, the presence of upper retainers had a negative impact on quality of life (p=0.018). The OHIP-14 value increased significantly from T0 to T1 (p=0.014), regardless of the presence of retainers. The fracture or debonding of the retainer reported by the patient was the only variable that had a negative impact on OHRQoL (p=0.05).

CONCLUSION

The use of fixed upper retainers suggests a negative impact on the quality of life of the orthodontic patient after the end of orthodontic treatment. This impact, however, is negligible in the long term, except when associated with fracture or debonding. This study emphasizes the need for continuous follow-up of orthodontic patients during the retention period.

Low translational and rotational movements with 2-point stainless-steel retainers over a period of 1 and 3 years

OBJECTIVES

Long-term stabilization of orthodontic treatment outcomes is an everyday challenge in orthodontics. The use of permanently attached lingual retainers has become gold standard. However, in some cases, patients with fixed lingual retainers show retainer-associated side effects. Aiming to reduce these side effects, clinical knowledge about how tooth and arch form stability adaption takes place over time is important to improve long-term retention protocols. Therefore, the present study aimed to investigate occlusion stability and risks for a newly developing malocclusion in a time-dependent manner in patients being treated with permanent 2‑point steel retainers.

MATERIALS AND METHODS

In this retrospective cohort study, a total of 66 consecutive patients with round stainless-steel retainers were analyzed for postorthodontic occlusion changes after 1 year (group 1, n = 33) and 3 years (group 2, n = 33). Digital Standard Tessellation Language (STL) datasets of the lower jaw were obtained before retainer insertion (T0), and after a 1- (T1) or 3‑year (T2) retention period. Using superimposition software, T1 and T2 situations were compared to T0 regarding rotational and translational changes in tooth positions in all three dimensions.

RESULTS

Occlusion changes were low in both groups. The investigated lower canines were nearly stable in the 1‑ and 3‑year group, although a retention-time-dependent increase in tooth position change of the central and lateral incisors could be observed.

CONCLUSION

The present data provide evidence for time-dependent development of posttherapeutic occlusal adaption limited to central and lateral incisors in patients treated with a 2-point retainer. The observed occlusal changes should be interpreted as an occlusal adaption process rather than severe posttreatment changes associated with the orthodontic retainer.

Failure frequency of fixed mandibular retainers after pre-treatment of the enamel surface with pumice versus sandblasting-a randomized controlled trial

BACKGROUND/OBJECTIVES

To compare retainer survival, periodontal health, and caries implications of fixed lower retainers bonded after pre-treatment of the enamel surface with either pumice or sandblasting.

TRIAL DESIGN

Two-arm parallel-group, two-center randomized controlled clinical trial.

METHODS

One hundred sixty patients (101 females, 59 males, mean age: 17.9) requiring mandibular retainers were consecutively recruited. Patients were randomly allocated to have pre-treatment of the enamel surface with either pumice (n = 80) or sandblasting (n = 80). The primary outcome was retainer survival at 3 (T1) and 12 months (T2) control. Secondary outcomes were carious lesions and periodontal health: plaque index (PI), gingival index (GI), calculus index (CI), and probing depth (PD). The randomization sequence was generated using an online randomization and allocation concealment was secured by contacting the sequence generator for treatment assignment. Blinding was not possible at T0 due to the nature of the intervention. Statistical analyses were carried out using the t-test, Fisher's exact test, repeated measure analysis of variance, and log rank test.

RESULTS

Overall, the risk of bonding failure at T1 was 6.7 per cent and at T2 6.9 per cent. There were no statistically significant differences in failure rate between the two groups, neither at T1 (P = 1.000) nor at T2 (P = 0.360). No statistically significant differences were found for the intercanine periodontal indices GI, PI, CI, PD, and caries between the two groups at T0 and T1. At T2, significantly more gingivitis and plaque were seen in the sandblasting group (P = 0.05 and P = 0.047, respectively) compared with the pumice group. Calculus increased during the follow-up period in both groups (P ≤ 0.001) as well as plaque levels (P ≤ 0.001 and P = 0.025, respectively). No harm was reported.

CONCLUSIONS

Enamel sandblasting prior to bonding mandibular retainers is not better at preventing bonding failure.

REGISTRATION

275767 (https://www.researchweb.org/is/sverige).

Risk factors for orthodontic fixed retention failure: A retrospective controlled study

Objective

: To investigate the potential correlation between fixed orthodontic retention failure and several patient- and treatment-related factors.

Methods

: Patients finishing treatment with fixed appliances between 2016 and 2017 were retrospectively included in this study. Those not showing fixed retention failure were considered as control group. Patients with fixed retention failure were considered as the experimental group. Additionally, patients with failure of fixed retainers in the period of June 2019 to March 2021 were prospectively identified and included in the experimental group. The location of the first retention failure, sex, pretreatment dental occlusion, facial characteristics, posttreatment dental occlusion, treatment approach and presence of oral habits were compared between groups before and after treatment separately by using a Fisher exact test and a Mann-Whitney U test.

Results

: 206 patients with fixed retention failure were included, 169 in the mandibular and 74 in the maxillary jaws. Significant correlations were observed between retention failure in the mandibular jaws and mandibular arch length discrepancy (P = 0.010), post-treatment growth pattern (P = 0.041), nail biting (P < 0.001) and abnormal tongue function (P = 0.002). Retention failure in the maxillary jaws was more frequent in patients with IPR in the mandibular jaws (P = 0.005) and abnormal tongue function (P = 0.021).

Conclusions

: This study suggests a correlation between fixed retention failure and parafunctional habits, such as nail biting and abnormal tongue function. Prospective studies with larger study populations could further confirm these results.

An assessment of the impact of adhesive coverage and wire type on fixed retainer failures and force propagation along two types of orthodontic retainer wires: an in vitro study

OBJECTIVES

To evaluate the force required to promote the failure of fixed orthodontic retainers with different adhesive (composite) coverage and to assess the presence and extent of force propagation with two different orthodontic retainer wires.

MATERIALS AND METHODS

Ortho-FlexTech and Ortho-Care Perform (0.0175 inches), each of 15-cm length, were bonded on acrylic blocks with different adhesive surface diameters (2 mm, 3 mm, 4 mm, and 5 mm). The samples (n = 160) were subjected to a tensile pull-out test, and debonding force was recorded. Fixed retainers using two different wires and 4-mm adhesive diameter were bonded on acrylic bases resembling a maxillary dental arch (n = 72). The retainers were loaded occluso-apically until the first sign of failure while being video recorded. Individual frames of the recordings were extracted and compared. A force propagation scoring index was developed to quantify the extent of force transmission under load.

RESULTS

A 4-mm adhesive surface diameter required the highest debonding force for both retainer wires with significant differences compared with 2 mm (P < .001; 95% confidence interval [CI]: 8.69, 21.69) and 3 mm (P = .026; 95% CI: 0.60, 13.59). Force propagation scores were significantly higher for Ortho-Care Perform.

CONCLUSIONS

Based on this laboratory-based assessment, consideration should be given to the fabrication of maxillary fixed retainers using a minimum of 4-mm diameter composite coverage on each tooth. Force appeared to propagate more readily with Ortho-Care Perform than with a flexible chain alternative. This may risk stress accumulation at the terminal ends with potential for associated unwanted tooth movement in the presence of intact fixed retainers.

Evaluation of digital construction, production and intraoral position accuracy of novel 3D CAD/CAM titanium retainers

OBJECTIVES

New opportunities have arisen to manufacture three-dimensional computer-aided design/computer-aided manufacturing (3D CAD/CAM) retainers from titanium blocks by digital cutting technology. These novel technologies need to fulfill requirements regarding digital planning and position accuracy. The aim of the present study was to investigate the digital construction, the CAD/CAM production and the intraoral positioning accuracy of custom-manufactured novel 3D CAD/CAM titanium retainers.

MATERIALS AND METHODS

A total of 37 prime4me® RETAIN3R (Dentaurum, Ispringen, Germany) retainers were inserted to stabilize the upper anterior front teeth. Following insertion, an intraoral scan was used to record the position. The intraoral position was compared to the virtual setup using 3D superimposition software. Measurement points were evaluated in all three dimensions (horizontal, sagittal and vertical planes). Data were analyzed using Kruskal-Wallis test followed by Dunn's multiple comparison test.

RESULTS

A total of 185 measurements were performed. The horizontal plane and the sagittal plane demonstrated a high level of positioning accuracy between the planned and the intraoral position. Statistically significant deviations between the preceding virtual setup and the intraoral situation were observed in the vertical dimension. Within the retainer, the intraoral positioning accuracy decreased for the measurement points in the direction of the distal retainer segment.

CONCLUSION

Based on the results, the present study shows a high level of congruence between the 3D virtually planning and the final intraoral position of the fabricated novel 3D CAD/CAM titanium retainers.

A cost analysis of orthodontic space closure and implant treatment in patients missing maxillary lateral incisors with a long-term perspective

OBJECTIVE

Few studies within orthodontics present both economic and clinical findings. Missing maxillary lateral incisors is a frequently occurring anomaly. The treatment alternatives most used are orthodontic space closure and prosthetic replacement of the missing tooth. Our aim is to compare the total societal costs of orthodontic space closure (SC) and implant therapy (IT) in patients missing maxillary lateral incisors.

METHODS

Records of 32 patients treated with SC (n = 18) or IT (n = 14) due to missing maxillary lateral incisors were retrieved from the archives. Direct costs and indirect costs in the short- and long-term were analysed using a cost analysis with a societal perspective up of to 12 years post-treatment.

RESULTS

Comparing cases treated with SC and IT, the difference in direct short-term costs for treatment is €735.54, whereas SC is the least costly. There is no difference between SC and IT in short-term parent loss of productivity, long-term loss of productivity, costs for transportation, or direct long-term costs. A difference was found between SC and IT-in favour of SC-when comparing patients' loss of productivity (P = 0.007), short-term societal costs (P < 0.001), long-term societal costs (P = 0.037), and total societal costs (P < 0.001).

LIMITATIONS

There is a limited number of patient records. Local factors such as subsidies, urban versus rural areas, taxes, etc. can influence monetary variables, so the transferability to other settings may be limited.

CONCLUSION

Patients treated with SC have a lower total societal cost compared to patients treated with IT. There was a difference in productivity loss for patients between SC and IT; however, concerning other indirect parameters and direct long-term costs, there was no difference between the two treatments.

Indirect vs direct bonding of mandibular fixed retainers in orthodontic patients: Comparison of retainer failures and posttreatment stability. A 5-year follow-up of a single-center randomized controlled trial

INTRODUCTION

This 2-arm parallel trial aimed to assess the number of failures of mandibular fixed retainers bonded with direct and indirect bonding methods at a 5-year follow-up and investigate the stability of intercanine and interpremolar distances.

METHODS

Consecutive patients from the clinic of the University of Geneva (Switzerland) were randomly allocated to either direct or indirect bonding of a mandibular fixed retainer at the end of orthodontic treatment. Inclusion criteria included the presence of all mandibular incisors and canines; and the absence of active caries, restorations, fractures, or periodontal disease of these teeth. The patients were randomized in blocks of 4 using an online randomization service, with allocation concealment secured by contacting the sequence generator for assignment. Two and 5 years (T5) after bonding the retainers, the patients were recalled, and impressions were taken. The primary outcome was the 5-year survival of the mandibular fixed retainer bonded with both bonding methods. The secondary outcomes were the intercanine and interpremolar distances and the assessment of unexpected posttreatment changes (ie, changes in torque and/or rotations of the mandibular incisors and canines). Blinding was applicable for outcome assessment only. Kaplan-Meier curves were generated, and a Cox proportional hazard regression model was fitted for bonding type, age, and treatment. Linear mixed models were fitted to intercanine and interpremolar distances: bonding type, time, age, and treatment were modeled as outcomes.

RESULTS

Sixty-four patients were randomized in a 1:1 ratio. At T5, 6 patients without previous failure were lost to follow-up from each group. At T5, the fixed retainer was debonded in 14 patients (54%) for each group. The hazard ratio of indirect bonding to direct bonding was 1.09 (95% confidence interval, 0.26-4.60; P = 0.91); there was no statistically significant difference in survival between the groups. Regarding intercanine and interpremolar distances, none of the tested prognostic factors reached statistical significance. Unexpected posttreatment changes were observed in 6 failure-free patients, all bonded with the direct bonding method. Only 1 patient required debonding of the fixed retainer. No other serious harms were observed.

CONCLUSIONS

The 5-year survival rate for both direct and indirect bonding methods was 46%, without a statistically significant difference between bonding methods. Bonded retainers were effective in maintaining intercanine and interpremolar distances. Unexpected posttreatment changes were only observed with retainers bonded with the direct bonding method.

REGISTRATION

The trial was not registered.

PROTOCOL

The protocol was not published before trial commencement.

FUNDING

No funding or conflict of interest to be declared.

“Wire Syndrome” Following Bonded Orthodontic Retainers: A Systematic Review of the Literature

(1) Background and objective: Tooth movements described as unexplained, aberrant, unexpected, unwanted, or undesirable can occur in the presence of an intact orthodontic retention wire, without detachment or fracture. This iatrogenic phenomenon, known little or not by many practitioners, responsible for significant dental and periodontal complications, both functional and aesthetic, is called “Wire Syndrome” (WS). It is therefore considered an undesirable event of bonded orthodontic retainers, which must be differentiated from an orthodontic relapse. The objective was to perform, for the first time, a systematic review of the literature in order to define the prevalence of WS and to study its associated clinical characteristics. (2) Methods: A systematic review of the literature was performed following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and recommendations using an electronic search strategy on four databases complemented by a manual search. All the prospective and retrospective clinical studies, including case reports and series, written in English or French, clearly mentioning the description, detection, or management of WS were included. Three independent blinding review authors were involved in study selection, data extraction, and bias assessment using the Mixed Methods Appraisal Tool (MMAT). (3) Results: Of 1891 results, 20 articles published between 2007 and 2021 fulfilled the inclusion criteria, with a globally high risk of bias since 16 articles were case report/series. The analysis of each article allowed the highlighting of WS through 13 categories, as follows: prevalence, apparition delay, patient characteristics, arch and tooth involved, families of movements, dental and periodontal consequences, type of wire, risk factors, etiologies, treatment, and preventive approach. (4) Conclusion: This systematic review of the literature elaborated a synthesis on WS, allowing general practitioners, periodontists, and orthodontists to understand this adverse event, to facilitate the diagnostic approach, and to underline preventive measures against WS. This review was registered in the International Prospective Register of Systematic Reviews (PROSPERO; number CRD42021269297).

Innovative customized CAD/CAM nickel-titanium lingual retainer versus standard stainless-steel lingual retainer: A randomized controlled trial

Objective

To compare computer-aided design and computer-aided manufacturing (CAD/CAM) customized nitinol retainers with standard stainlesssteel fixed retainers over a 12-month study period.

Methods

This randomized controlled trial (RCT) was conducted on 62 patients randomly allocated to a control group that received stainless-steel retainers or a test group that received customized CAD/CAM nickel-titanium retainers. Four time points were defined: retainer placement (T0) and 1-month (T1), 6-month (T2), and 12-month (T3) follow-up appointments. At each time point, Little's irregularity index (LII) (primary endpoint) and dental stability measurements such as intercanine width were recorded in addition to assessment of periodontal parameters. Radiological measurements such as the incisor mandibular plane angle (IMPA) were recorded at T0 and T3. Failure events (wire integrity or debonding) were assessed at each time point.

Results

From T0 to T3, LII and other dental measurements showed no significant differences between the two groups. The data for periodontal parameters remained stable over the study period, except for the gingival index, which was slightly, but significantly, higher in the test group at T3 (p = 0.039). The IMPA angle showed no intergroup difference. The two groups showed no significant difference in debonding events.

Conclusions

This RCT conducted over a 12-month period demonstrated no significant difference between customized CAD/CAM nickel-titanium lingual retainers and standard stainlesssteel lingual retainers in terms of dental anterior stability and retainer survival. Both retainers eventually appeared to be equally effective in maintaining periodontal health.

3D-analysis of unwanted tooth movements despite bonded orthodontic retainers: a pilot study

Background

Recently, reports of unwanted tooth movements despite intact orthodontic bonded retainers have increased. These movements are not subject to relapse but are classified as a new developed malocclusion. The aims of the present pilot study were to analyze the prevalence of unwanted tooth movements despite intact bonded cuspid-to-cuspid retainers and to identify possible predisposing factors.

Materials and methods

Plaster casts of all patients finishing orthodontic treatment during three consecutive years were assessed before treatment (T0), after multibracket appliance debonding (T1) and after two years of retention (T2). After multibracket appliance treatment, all patients received a cuspid-to-cuspid flexible spiral wire retainer bonded to each tooth of the retained segment in the upper and lower jaw. The study group (SG) consisted of 44 patients (16 male, 28 female) with tooth movements (T1–T2) of the retained segment despite intact bonded cuspid-to-cuspid retainer and the control group (CG) of 43 patients (19 male, 24 female) without unwanted tooth movements. The casts of the SG were digitized, superimposed and measured. Using the Chi-square test, Fisher´s exact test and Mann–Whitney-U-test (p < 0.05), mandibular plane angle, incisor proclination, oral dysfunctions or habits (T0) and intercanine distance, overjet and interincisal relationship (T0, T1, T2) were compared between SG and CG.

Results

The prevalence of patients with unwanted tooth movements in one or both jaws was 27.0%. Maxillary retainers were affected more often (20.9%) than mandibular retainers (14.1%). The median amount of tooth movements was 0 to 0.66 mm with large interindividual variations. Oral dysfunctions or habits at T0, such as a lack of interincisal contact at all time points, were associated with unwanted tooth movements.

Conclusion

Unwanted tooth movements occurred more often with maxillary than mandibular retainers. Patients with oral dysfunctions/habits and without interincisal contact had a higher prevalence of unwanted tooth movements.

Approaches of Turkish Dentists in Cases of Orthodontic Lingual Retainer Failures

OBJECTIVE

This study aimed to investigate the approaches of Turkish dentists in cases of orthodontic lingual retainer failures.

METHODS

A self-administered questionnaire was used to quantify dentists' approaches to lingual retainer failures. The first part of the study investigated the demographic characteristics. In the second part, dentists' approaches to cases of failed retainers were assessed. The third part had questions related to the type of retainers bonded solely to the canines or to all the 6 anterior teeth. Descriptive statistics were done with Pearson's χ2 test, and Mann-Whitney U test was used.

RESULTS

A total of 320 Turkish dentists participated in the survey. Experienced and public dentists preferred to advise the patients whose retainers had failed to contact their orthodontist more frequently (p<0.05). Regarding their approach to patients who requested removal of the bonded retainer, inexperienced dentists more frequently preferred to refer the patients to an orthodontist (p<0.05). With regard to factors affecting the choice to remove a bonded retainer, the most and the least importance were attributed to the orthodontist's opinion and the patient's demand, respectively.

CONCLUSION

Turkish dentists prefer referring their patients to orthodontists rather than performing procedures in cases of failure associated with bonded retainers. Different demographic characteristics seem to have an impact on these approaches.

The Maryland bridge retainer: A modification of a Maryland bridge

Preservation of the maxillary lateral incisor space after orthodontic treatment in an adolescent patient traditionally requires the use of a retainer with a lateral pontic, commonly referred to as a "flipper," which is minimally effective in the long term. This article illustrates a technique for chairside fabrication of a Maryland bridge retainer for semi-permanent retention. A stainless steel braided palatal wire is bonded to the anterior teeth. A pontic is then built intraorally with flowable composite, using the palatal wire as scaffolding. The retainer is maintained until the patient is of age for a more permanent restoration.

Survival of maxillary and mandibular bonded retainers 10 to 15 years after orthodontic treatment: a retrospective observational study

BACKGROUND

The long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers.

TRIAL DESIGN

Retrospective cohort study.

METHODS

Eighty-eight patients in retention 10-15 years after orthodontic treatment were included. The type of failure; number of failures per tooth, per patient, and retainer; and adverse effects were assessed by (1) a questionnaire, (2) clinical examination, and (3) screening patients' clinical charts. Descriptive statistics were calculated and a Cox regression was used to assess possible predictors for mandibular retainer survival.

RESULTS AND CONCLUSIONS

In the mandible, 47 (53.4%) .016″ × .022″ braided stainless steel retainers (SS) were bonded to all six anterior teeth, and 41 (46.6%) .027″ β-titanium (TMA) retainers were bonded to the canines only. From the SS retainers 40.4% and of the TMA retainers 61% had no failures during the whole observation period. SS failures per retainer were 2.17 (3.15) vs. 0.66 (1.03) for TMA. The type of retainer was the only significant predictor for failure. In the maxilla, 82 (93.2%) .016″ × .022″ braided SS retainers were bonded to all four incisors and six retainers (6.8%) to all six anterior teeth. The latter group was not further analyzed due to the small sample size. From the retainers bonded to all four incisors, 74.4% had no failure during the whole observation period. SS average number of failures per retainer bonded to the four incisors was 1.14 (SD 2.93). Overall, detachments were the most frequent type of first failure followed by composite damage. From the original mandibular retainers 98.9% and of the original maxillary retainers 97.6% were still in situ 10-15 years after debonding. No adverse torque changes were observed.

LIMITATIONS

Potential effects of selection bias, information bias, and attrition bias as well as possible confounding factors cannot be fully excluded in this study.

Development of a clinical practice guideline for orthodontic retention

OBJECTIVES

To develop a clinical practice guideline (CPG) for orthodontic retention (OR).

MATERIALS AND METHODS

The CPG was developed according to the AGREE II instrument and EBRO (Dutch methodology for evidence-based guideline development). Reporting was done according the RIGHT statement. A Task Force developed clinical questions regarding OR. To answer these questions, a systematic literature search in PubMed and EMBASE was performed. Two independent researchers identified and selected studies, assessed risk of bias using Cochrane RoB tool and rated quality of evidence using GRADE. The Task Force formulated considerations and recommendations after discussing the evidence. The concept CPG was sent for commentary to all relevant stakeholders.

RESULT

One systematic review-with 15 studies-met the inclusion criteria. In case of low evidence and lack of outcome measures, expert-based considerations were developed. Over four meetings, the Task Force reached consensus on considerations and recommendations, after which the concept CPG was ready for the commentary phase. After processing the comments, the CPG was presented to the Dutch Association of Orthodontists, whereafter authorization followed.

LIMITATIONS

The paucity of evidence-based studies concerning OR and the reporting of measurable patient outcomes.

CONCLUSION

This CPG offers practitioner recommendations for best practice regarding OR, may reduce variation between practices and assists with patient aftercare. A carefully chosen retention procedure for individual patients, combined with clear information and communication between orthodontist, dentist and patient will contribute to long-term maintenance of orthodontic treatment results.

Comparison of the different retention appliances produced using CAD/CAM and conventional methods and different surface roughening methods

The purposes of this study are to conduct an in vitro comparison of the shear bond strength, breakage mode, and wire deformation of three different types of retainers and to compare the subsequent enamel surface changes. Two hundred seventy intact lower incisor teeth were embedded in acrylic blocks in pairs. Dead wire and CAD/CAM-fabricated and fiber-reinforced wires were applied to the teeth roughened with acid and Er:YAG or Er,Cr:YSGG laser. The surface roughness was observed by scanning electron and atomic force microscopy. The samples were analyzed for shear bonds. The dead wire and acid group were found to have the highest bonding strength and the strengths for all groups in which acid was used as an agent were found to be higher than others. Deformation of retainers was most noted in the dead wire-acid group. Among all the groups, the CAD/CAM-fabricated wire group showed the least deformation, with no deformation observed. In this study, it was determined that there is a significant correlation between ARI scores and agents. Consequently, acid etching was found to create more enamel surface roughness than laser groups. It was also seen that the combined use of the acid method and dead soft wire had the highest bond strength, even though it was not statistically significant. It was concluded that CAD/CAM-fabricated wire provides the opportunity for reuse in clinical applications due to its lack of deformation, being more conservative for the patient, and being more advantageous for the clinician in terms of session time, considering the residual adhesive amount left on the enamel surface.

The effect of prior sandblasting of the wire on the shear bond strength of two different types of lingual retainers

PURPOSE

The aim of this study was to evaluate the effect of total surface sandblasting on the shear bond strength of two different retainer wires. The null hypothesis was that there is no difference in the bond strength of the two types of lingual retainer wires when they are sandblasted.

MATERIALS AND METHODS

One hundred and sixty human premolar teeth were equally divided into four groups (n=40). A pair of teeth was embedded in self-curing acrylic resin and polished. Retainer wires were applied on the etched and rinsed surfaces of the teeth. Four retainers were used: group 1: braided retainer (0.010×0.028″, Ortho Technology); group 2: sandblasted braided retainer (0.010×0.028″, Ortho Technology); group 3: coaxial retainer (0.0215″ Coaxial, 3M) and group 4: sandblasted coaxial retainer (0.0215″ Coaxial, 3M). The specimens were tested using a universal test machine in shear mode with a crosshead speed of one mm/min.

RESULTS

One-way analysis of variance (Anova) was used to determine the significant differences among the groups. There was no significant difference (P=0.117) among the groups according to this test.

CONCLUSIONS

The null hypothesis was accepted. There was no statistically significant difference among the shear bond strength values of the four groups.

Retention practices and factors affecting retainer choice among orthodontists in Saudi Arabia

Objectives:

To identify the retention protocols practiced by orthodontists in Saudi Arabia, and the factors affecting retainer choice.

Methods:

This cross-sectional study took place between February and March of 2015 at the College of Dentistry, University of Dammam, Dammam, Saudi Arabia. A previously tested electronic survey of 34 items was sent to all 1,200 orthodontic members of the Saudi Orthodontic Society. The questionnaire elicited data on the subjects’ demographics, orthodontic treatment practices, retention, and post-retention protocols.

Results:

One hundred and sixty-seven (13.9%) responses were received during the study period. The results showed predominant use of Hawley in the maxillary arch (61.3%), and fixed lingual in the mandibular arch (58.5%). Approximately 90.3% recommended full-time maxillary removable retainer wear. Overall, orthodontists who performed fewer extractions tended to use fixed retainers, and those who performed more extractions used removable retainers (p=0.018). Interproximal enamel reduction was used by 28% of the respondents as an adjunct procedure to enhance retention. Approximately 64% practiced a post-retention phase of retainer wear. Participants who used removable retainers most commonly prescribed lifetime retention.

Conclusion:

Hawley in the maxilla, and fixed lingual in the mandible were the most common retention protocols prescribed. Lifetime retention was the most common choice for participants who used removable retainers, especially when extractions were carried out.

An Innovative Approach to Retention: Thermoplastic Retainer

AIM

The aim of this study was to design and introduce a retainer that overcomes the common shortcomings seen in other retainers.

MATERIALS AND METHODS

Hard thermoplastic sheet of 0.5 mm thickness is vacuum or pressure-molded onto the patient cast. Lingual portion of the retainer is trimmed according to the contours of the anterior teeth. Contact points between the maxillary and mandibular anterior teeth are marked on the retainer and reduced. Punch cut holes are placed on the retainer for the exit of flash and air bubbles while fixation. The retainer is bonded onto the lingual surface of the anterior teeth using composite.

RESULTS

A 1-month review of the retainer showed no patient discomfort, occlusal interference, or bond failure. The aim of the article was found to have been achieved.

CONCLUSION

Initial evaluation has shown positive findings. Long-term clinical findings will determine the overall success of this new retainer.

CLINICAL SIGNIFICANCE

As compared with other retainers, thermoplastic retainer has shown reduced tendency to debond from occlusal forces, decreased patient discomfort, and occlusal interference.

Memotain: A CAD/CAM nickel-titanium lingual retainer

Approximately 1/2 of maxillary and 1/5 of mandibular multi-stranded lingual retainers fail during retention in some form, either bond failure or wire breakage. Memotain is a new CAD/CAM fabricated lingual retainer wire made of custom-cut nickel-titanium, as an alternative to multi-stranded lingual retainers. It offers numerous perceived advantages to the traditional multi-stranded stainless steel wire, including precision fit, avoidance of interferences, corrosion resistance and even the potential for minor tooth movement as an active lingual retainer.

The Limitations of Short-Term Orthodontics and Why We Still Need Specialists – A Review of the Current Literature

Short-term orthodontics (STO) serves to align anterior teeth. It has become popular in cosmetic dentistry as an alternative to destructive veneers and lengthy conventional orthodontics. The aim of this article is to raise awareness of the clinical limitations of STO and highlight some of the difficulties encountered with orthodontic retention. It also gives an overview of accredited training available to dentists who wish to develop their orthodontic skills. Clinical relevance: Greater awareness of the clinical limitations of short-term orthodontics will aid GDPs in appropriately selecting their cases and obtaining informed consent from patients. In addition, the article serves as encouragement for those GDPs wishing to develop their orthodontic skills and pursue further accredited training.

Torque resistance of different stainless steel wires commonly used for fixed retainers in orthodontics

OBJECTIVE

Movements of teeth splinted by fixed retention wires after orthodontic treatment have been observed. The aetiological factors for these movements are unknown. The aim of this in vitro study was to compare the resistance to torque of different stainless steel wires commonly used for fixed retainers in orthodontics.

MATERIALS AND METHODS

Torquing moments acting on a retainer wire were measured in a mechanical force testing system by applying buccal crown torque to an upper lateral incisor in both a 3-teeth and in a 2-teeth setup. Seven stainless steel wires with different shape, type (plain, braided, coaxial, or chain) and dimensions were selected for this study.

RESULTS

For a torquing angle of 16.2° in the 3-teeth setup torsion moments can vary between 390 cNmm and 3299 cNmm depending on the retainer wire. For the 2-teeth setup the torsion moments are much smaller. Exposure to the flame of a butane-gas torch for 10 seconds to anneal the wire reduces the stiffness of the retainer wire.

CONCLUSIONS

Clinicians must select wires for fixed retainers very carefully since the difference in resistance to torque is large. A high level of torque control can be achieved with a plain 0.016 × 0.016-inch or a braided 0.016 × 0.022-inch stainless steel wire. A tooth attached by a retainer wire to only one neighbouring tooth is less resistant to torque than a tooth connected to two neighbouring teeth. Annealing a retainer wire with a flame reduces the stiffness of the wire markedly and can lead to a non-uniform and non-reproducible effect.

A survey of general dentists regarding orthodontic retention procedures

AIM

To explore 1. how Swiss general dentists deal with complications associated with fixed orthodontic retainers, 2. collaboration between general dentists and orthodontists with regards to the organization and responsibility for long-term follow-up of orthodontic retainers, and 3. the need for standardized clinical guidelines regarding orthodontic retention.

METHODS

A structured questionnaire was sent to 201 randomly selected dentists. They were asked about their experience with retainers, opinions regarding the advantages and disadvantages of different types of retainers, responsibility for patients wearing bonded retention and the communication between orthodontists and general dentists. Statistical analysis was carried out using SPSS software.

RESULTS

The response rate was 61 per cent. About 55 per cent of the respondents had had experience with bonding fixed retainers and even more were familiar with their follow-up and repair. In case of complications, dentists usually contacted orthodontists according to the following rule: the more severe the complication, the more intense the communication. Most dentists hesitated to remove retainers when requested to do so by the patient and attempted to convince them to continue wearing them. Retainers bonded to all six anterior teeth were considered more efficient than those bonded to canines only; however, possible side effects (e.g. unwanted changes of the torque) were not well known. 66.4 per cent respondents were willing to take responsibility for patients in retention as early as 6 months after retainer placement. 93.2 per cent respondents would welcome the establishment of standardized guidelines.

CONCLUSIONS

Swiss general dentists have good knowledge of orthodontic retention and follow-up procedures. Nevertheless, introduction of clinical guidelines including information on the possible side-effects of bonded retention is justified.

Novel lingual retainer created using CAD/CAM technology: evaluation of its positioning accuracy

OBJECTIVES

Permanent retention is currently the method of choice to stabilize orthodontic treatment results. Frequently, permanent retention schemes are adopted to prevent posttreatment changes in the esthetic zone of the anterior teeth. With increasingly prolonged times of intraoral device use, and retention to be provided in the maxilla despite limited space, the demands placed on well-planned and precise retainer positioning are becoming more exacting. The aim of the present study was to analyze the intraoral precision of lingual retainers made using computer-aided design and machining (CAD/CAM).

MATERIALS AND METHODS

A custom manufacturer (Retaintechnology; Cologne, Germany) employing innovative CAD/CAM technology was commissioned to fabricate 16 lingual retainers. Following intraoral insertion using the manufacturer's recommended transfer system, impressions of the intraoral situations were taken and scanned for digitization. On this basis, the intraoral retainer positions were compared to the preceding virtual setups by superimposition with the manufacturer's datasets. Three-dimensional processing software (Geomagic Qualify 2012; Geomagic) was used to analyze the retainers, based on a total of 80 interproximal sites, for deviations from their planned positions along the horizontal (x-), sagittal (y-), and vertical (z-) axes. These deviations of the achieved from the intended positions were considered clinically relevant if ≥ 0.5 mm and, based on this premise, were subjected to a t-test with statistical software (Prism; GraphPad).

RESULTS

The intraoral retainer positions were found to correlate closely with the preceding virtual setups (i.e., the positions as they had been planned by the custom manufacturer). Positional deviations were significantly less than 0.5 mm. They were very small in the horizontal and sagittal planes and moderately larger in the vertical plane.

CONCLUSION

Highly precise intraoral results may be achieved by transferring three-dimensional virtual setups for lingual retainers to the actual patients. This CAD/CAM strategy of making retainers can offer high predictability even in anatomically demanding regions and in the presence of limited space.

Long-term bonded retention after closure of maxillary midline diastema

INTRODUCTION

The objectives of this study were to evaluate fixed bonded palatal surface retainers between the maxillary central incisors that were placed to maintain midline diastema closure and record their longevity, proclivity for damage, and periodontal health of the central incisors in patients 5 or more years after treatment.

METHODS

Twenty-nine subjects were contacted and interviewed by phone concerning the status of their bonded retainer and midline diastema. Eleven subjects with intact retainers came for a periodontal health evaluation of the maxillary central incisors. The measures used were the plaque index, the periodontal screening and recording score, and the gingival index. A split-mouth design was used. Statistical analyses of retainer duration, damage probability, and gingival health were performed.

RESULTS

Of the 29 subjects, 52% of the initial retainers were in place for an average of 23 years. For the total of 34 bonded retainers, the mean longevity was 17 years. The risk of breakage for any particular year the retainer was in place was 2%. The mean differences in scores between the maxillary central incisors and the control teeth were -0.06 for the plaque index, -0.14 for the periodontal screening and recording score, and -0.11 for the gingival index. Statistical tests on the differences indicated no evidence that the long-term presence of the bonded palatal surface retainer adversely affected the periodontal health of the maxillary central incisors.

CONCLUSIONS

The study's sample demonstrated that a bonded retainer for maintaining closure of a maxillary midline diastema can last an average of 17 years or more, with a yearly 2% chance of breakage and with no expected adverse effects on the periodontal health of the maxillary central incisors.

Truth or consequences: the potential implications of short-term cosmetic orthodontics for general dental practitioners

Until recently, cosmetic dentistry has focused on the use of traditional restorative techniques, bleaching and the so-called facial rejuvenators such as injectable dermal fillers and Botox. More latterly, the short-term use of aesthetic removable aligners and ceramic fixed appliance brackets have been promoted for use by general dental practitioners as a means of minimising the invasive amount of restorative dental treatment that would otherwise be required to achieve the desired degree of aesthetic improvement. Nevertheless, there are inherent risks and complications associated with short-term orthodontic treatments that are deliberately limited in their outcomes and these, together with the potential ramifications for the long-term dental health of patients, are discussed.

Anterior tooth alignment--recommendations for stability

This article considers the importance of current orthodontic practice in retention and stability when considering anterior tooth alignment.

CLINICAL RELEVANCE

With the exponential increase of general dentist-based orthodontic systems for anterior tooth alignment, with considerably shorter treatment times, practical recommendations along with a current literature review are required to improve success and outcome of the long-term result.

Debate: short-term orthodontics

Debate based on an opinion article published in the British Dental Journal entitled 'Truth or consequences: the potential implications of short-term cosmetic orthodontics for general dental practitioners' by R. A. C. Chate ( 2013; 215: 551-553; www.nature.com/bdj/journal/v215/n11/full/sj.bdj.2013.1140.html).