Orthodontic Retainers Research Articles

Ingestão acidental de contenção ortodôntica: o que fazer?

Os materiais odontológicos são relativamente raros de serem engolidos, ainda mais quando se trata de objetos ortodônticos. Entretanto, esse tipo de emergência pode surgir no ambiente da clínica odontológica. Embora o ideal seja evitar sua ocorrência, é necessário que o profissional saiba conduzir a situação, em casos que venha a acontecer. Portanto, o objetivo deste artigo foi realizar uma revisão da literatura e descrever um caso clínico de ingestão de contenção ortodôntica. Desta forma, exemplificar complicações oriundas da deglutição acidental e propor possibilidades de conduta. A fim de obter essas respostas, realizou-se de uma revisão da literatura associada a um estudo de caso sobre o tema em questão. Como resultados, obteve-se que a deglutição ou aspiração de aparelhos ou de componentes associados ao aparelho ortodôntico fixo ou removível são as categorias mais citadas na literatura. Independentemente da incidência, episódios como ingestão ou aspiração de corpo estranho são reconhecidos como possíveis complicações em Ortodontia. Quando os acidentes ocorrem fora do consultório odontológico, os pacientes geralmente estão em tratamento ortodôntico, o que representa menos de 10% do total de casos de deglutição acidental. Conclui-se que a investigação após a ingestão de qualquer componente de um aparelho ortodôntico é fundamental para levar a segurança do paciente e realizar qualquer encaminhamento médico necessário para atendimento de emergência a fim de evitar possíveis complicações.

Evaluation of magnetic resonance imaging artifacts caused by fixed orthodontic CAD/CAM retainers\u2014an in vitro study

ObjectivesMagnetic 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 methodsThree 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.ResultsTwistflex 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.ConclusionAll 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 relevanceCAD/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.

Biofilm Formation of Cariogenic Bacteria on Vanillin-Incorporated Orthodontic Retainer PMMA Resin

Orthodontic retainers made of poly methyl methacrylate (PMMA) resin are generally used after finished orthodontic treatment to hold teeth in the right position and avoid the shift out from the alignment. The use of these devices can place patients at greater risk of dental caries through the biofilm accumulation of caries-associated bacteria and food debris on the rough surfaces or inherent porosities of PMMA surfaces of appliances themselves. Vanillin, the major component of flavoring agent vanilla, has been demonstrated to have antimicrobial activity against many types of microorganisms. This study aimed to evaluate antimicrobial property of vanillin-incorporated orthodontic retainer PMMA resin on the biofilm formation of cariogenic bacteria. The self-curing orthodontic retainer PMMA resin samples were produced according to the percentage of vanillin adding (0%, 0.1% and 0.5% vanillin) (SCG Chemicals, Thailand). All samples were coated with sterile unstimulated saliva. Then the cariogenic bacterial suspensions of Streptococcus mutans ATCC 25715, Streptococcus sobrinus ATCC 33478, Lactobacillus casei ATCC 334 and Lactobacillus acidophilus ATCC 314 were added and incubated at 37°C in 5% CO2 atmosphere for 48 h to allow the biofilm formation. The amount of vital biofilm was determined by WST Microbial Cell Counting Kit (Dojindo Molecular Technologies, USA) at 460 nm. One-way ANOVA and Turkey’s test were employed for the statistical analysis. A significant inhibitory effect against all tested bacteria was observed in 0.5% vanillin incorporated samples compared with 0% vanillin. The percentage of biofilm reduction was 23-45%. The adding of 0.1% vanillin showed suppressive effect only on Lactobacillus spp. In conclusion, the incorporation of 0.5% vanillin to self-curing orthodontic retainer PMMA resin could significantly inhibit biofilm formation of cariogenic bacteria (S. mutans, S. sobrinus, L. casei and L. acidophilus). Using this PMMA resin, removable orthodontic appliances with antimicrobial property can be applied to prevent dental caries or tooth demineralization in orthodontic patients.

Retention Practices Among Orthodontists in Morocco

Introduction: Retention is the orthodontic treatment phase which ensures that the teeth are maintained in their corrected positions. There are currently various protocols of retention commonly adopted by orthodontists. The objective of this study is to evaluate the retention procedures which are used by orthodontists in the private practice.Materials and methods: This was a cross-sectional descriptive analytical study which targeted orthodontists in the city of Rabat- Morocco. 67 questionnaires were distribute to the orthodontists of private practice. The questionnaire was organized into seven sections representing specific information about the socio-demographic status of the respondents, selection of a retention system, details of commonly used fixed and removable retainers, the duration of the retention period, and follow up appointments, instructions for patients, finally the clinical problems encountered during the retainer period. Results: All orthodontists participating in the survey confirmed the indispensable use of an orthodontic retainer after active treatment. The fixed retainer was the preferred choice of the majority of our orthodontists in the mandibular arch for the different clinical situations whereas, at the maxillary arch, more than 30% of orthodontists use both types of retainer (fixed and removable). 62.5% of orthodontists choose a vacuum-formed retainer as a removable retainer. For fixed retainer, the bonded canine to canine was most preferred by the majority of orthodontists in the upper and lower arches. 50% of orthodontists recommend lifetime orthodontic retainer with follow-up appointments of 2 to 3 times/year. Conclusions: This survey provides an overview of orthodontic retention procedures adopted by orthodontists in the region. A multitude of responses let us conclude that guidelines are desired to find a common protocol.

\u201cClinical comparison of bond failure rate between two types of mandibular canine-canine bonded orthodontic retainers- a randomized clinical trial\u201d

BackgroundBonded retainers are widely used as they are esthetically pleasing, easily acceptable, provide greater stability, compliance free and causes no soft tissue irritation and speech problems. Though, fracture and bond failure are their shortcomings. Therefore, the objectives of this study were to evaluate the number of bond failures and type of failure pattern between two types of mandibular canine-canine bonded retainers.MethodsTotal 60 subjects were recruited initially and were assessed for eligibility, out of which 6 were excluded and 2 were lost to follow up. They were randomly divided into two groups. Fiber reinforced composite (FRC) retainers were inserted in group 1 subjects while group 2 subjects received multistranded stainless steel (MSW) retainers. The subjects were recalled after every 3 months over a period of 1 year. Bond failure rate and failure pattern based on adhesive remnant index were evaluated at each visit. The bond failure rate and failure pattern were compared between the two retainers by using Chi-square test.ResultsThe bond failure rates were 42.94% for FRC retainer and 31.41% for MSW retainer. Hence, total number of bond failures in both retainers were 37.17%. The difference of bond failure between two groups was statistically significant (p = 0.012). Type “0” failure pattern was detected commonly with both types of retainers (p < 0.001).ConclusionOur findings indicate that multistranded stainless steel wire retainer is a superior option to be used for fixed lingual retention in mandibular arch as it exhibited lower bond failure as compared to fiber reinforced composite retainer. Adhesive failure is the most common type of bond failure observed with both types of fixed retainers.Trial registrationID NCT03881813 (https://clinicaltrials.gov/); March 19, 2019, retrospective registration.

Clinical comparison between Multi-Stranded Wires and Single strand Ribbon wires used for lingual fixed retainers

BackgroundLong-term retention with fixed retainers with a high success rate seems to be a reasonable solution to minimize or prohibit relapse of orthodontic treatment.MethodsTwo hundred sixty patients between 13 and 30 years old were recruited for this study. The 0.0175 stainless steel twisted wire (G&H Orthodontics, USA) was compared with a single-strand ribbon titanium lingual retainer wire (Retainium, Reliance orthodontics, USA) was used. When treatment was completed, the retainers were bonded from canine to canine in the mandibular arch of the participants. In the follow-up visits, the patients were recalled every 3 months during the 24 months. Detachments, the time of debonding, and side effects were recorded. Statistical analysis was performed by a blinded statistician using a statistical package for Social Science (SPSS, Version20). After descriptive statistics, Kaplan-Meier analysis was performed to measure the survival rates of each retainer. P value < 0.05 was considered as significant.ResultsFinally, 138 patients who received twisted wire splint and 112 patients who received ribbon wire were included in the analysis. The average duration of success was about 23 months for twisted wire and ribbon wire, according to the Kaplan-Meier estimates. The analysis showed no significant overall difference between the treatments (p = 0.13). Failure rates in terms of detachments in all groups occurred at the enamel junction, and it was 25 in twisted retainer group (18.1%) and was 10 in ribbon retainer group (8.9%); the Kaplan-Meier analysis test detected a significant difference in the failure rates between the groups (p = 0/006).ConclusionsAlthough the conventional twisted stainless steel wire and single-strand titanium flat metal ribbon wire as fixed orthodontic retainers have the same clinical effects, it was shown that the ribbon wire has less failure in terms of detachments.

Long-term Effectiveness of Maxillary and Mandibular Bonded Orthodontic Retainers.

This retrospective cohort study investigated the long-term effectiveness of one type of maxillary and 2 types of mandibular fixed lingual retainers. Eighty orthodontic patients in retention for 10-15 years were included. Irregularity index, intercanine width, overjet (OJ) and overbite (OB) were measured on plaster models at 3 occasions: (T1) pre-treatment, (T2) post-treatment and (T3) 10-15 years post-treatment. Analyses assessed the effect of the retainer type and time on mandibular irregularity, intercanine width and retainer failure. In the mandible, the irregularity index increased (0.43 mm) between T2 and T3 for the 0.027" β-titanium (TMA) retainers bonded to canines only while it was stable (-0.02 mm) for the 0.016" x 0.022" braided stainless steel retainers (SS6) bonded to all six anterior teeth. The intercanine width was relatively stable in both groups during the entire observation period. In the maxilla, the irregularity index was stable between T2 and T3 (+0.07 mm). The intercanine width increased (+2.02 mm) during treatment T1-T2 and was stable (-0.02 mm) in the retention phase T2 to T3. In the mandible, SS6 retainers were slightly more effective in maintaining alignment compared to the TMA retainers. In the maxilla, the SS4 retainers without canine extensions were effective in maintaining alignment. All retainers were effective in maintaining the intercanine width.

Changes in occlusal surface area and occlusal force distribution following the wear of vacuum‐formed, hawley and bonded retainers: A controlled clinical trial

To evaluate the changes in occlusal surface area (OSA) and occlusal force distribution (OFD) following the wear of Vacuum-formed (VFR), Hawley (HR) and Bonded (BR) retainers, using T-Scan III. A total of 60 subjects using three different maxillary and mandibular orthodontic retainers, VFR (n:20), HR (n:20) and BR (n:20), were included in this study. The changes in OSA and OFD were evaluated using the T-Scan III. The evaluations were made 2hours after debonding orthodontic appliances (T0) and in the 3rd (T1) and 6th (T2) months of the retention phase. For left (LDA), right (RDA) and posterior dental arches (PDA), intragroup comparison of OSA showed significant increase in the VFR and HR groups at T1-T2 and T0-T2 time intervals and in the BR group at T0-T1 and T0-T2 time intervals. For the anterior dental arch (ADA), only the increase in the HR group at T0-T1 and T0-T2 time intervals was found significant. When compared between the groups, the changes between HR and BR groups detected at T1-T2 time interval for the RDA and at T0-T1 and T0-T2 time intervals for the ADA were found significant. Intragroup comparison of OFD displayed significant changes only in the BR group. At T0-T1 time interval, the decrease in the ADA and the increase in the PDA were found significant. Also, intergroup OFD comparison exhibited significant differences between HR and BR groups at T0-T1 time interval for ADA and PDA. Although no significant differences were found between the VFR group, the increase in OSA occurred faster in the PDA in the BR group, whereas in the ADA it was significant only in the HR group.

Fear of the Relapse: Effect of Composite Type on Adhesion Efficacy of Upper and Lower Orthodontic Fixed Retainers: In Vitro Investigation and Randomized Clinical Trial.

The aim of this laboratory and clinical study is to determine the reliability of the flowable nanocomposite Filtek Supreme XTE (FL) for the adhesion of orthodontic retainers, compared to highly filled orthodontic resin Transbond XT (XT). Portions of a round section multistranded wire (Ortosmail Krugg) were bonded to 40 bovine incisors with Scotchbond Universal in total-etch modality. For group one (XT, 20 samples), the orthodontic resin was used, whereas in group two (FL, 20 samples), the flowable one. Specimens were placed into a universal testing machine which applied a shear force on retainers with a crosshead speed of one/minute. Shear bond strength (SBS) and adhesive remnant index (ARI) scores were calculated. In the clinical trial, 100 patients requiring a canine-to-canine palatal and lingual retainer were randomly divided into two groups, according to the resin used for bonding procedure: the orthodontic in group one (XT, 50 participants) and the flowable in group two (FL, 50 participants). Monthly visits were carried out over a 24-month follow up to assess any detachment occurring on teeth of both arches. All data were submitted to statistical analysis. In vitro, FL reported a significant lower mean SBS, whereas no significant differences in ARI were reported between the two groups which both showed a major frequency of scores “1” and “2”. At the end of the 24-month follow up, FL reported significantly higher failure rates in both arches besides a significantly lower survival rate starting from the sixth month after retainers bonding. According to the results assessed in vitro and clinically, XT would be preferable to FL when performing retainers bonding procedure.

Glass Fiber Reinforced Composite Orthodontic Retainer: In Vitro Effect of Tooth Brushing on the Surface Wear and Mechanical Properties.

Fiber reinforced composites (FRCs) are metal free materials that have many applications in dentistry. In clinical orthodontics, they are used as retainers after active treatment in order to avoid relapse. However, although the modulus of the elasticity of FRCs is low, the rigidity of the material in the form of a relatively thick retainer with a surface cover of a flowable resin composite is known to have higher structural rigidity than stainless steel splints. The aim of the present study is to measure load and bending stress of stainless steel wires, as well as flowable resin composite covered and spot-bonded FRC retainer materials after tooth brushing. These materials were tested with a three point bending test for three different conditions: no brushing, 26 min of brushing, and 60 min of brushing. SEM images were taken before and after different times of tooth brushing. Results showed that stainless steel was not significantly affected by tooth brushing. On the other hand, a significant reduction of values at maximum load at fracture was reported for both FRC groups, and uncovered FRCs were most affected. Concerning maximum bending stress, no significant reduction by pretreatment conditions was reported for the materials tested. SEM images showed no evident wear for stainless steel. Flowable resin composite covered FRCs showed some signs of composite wear, whereas spot-bonded FRCs, i.e., without the surface cover of a flowable resin composite, showed signs of wear on the FRC and exposed glass fibers from the FRC’s polymer matrix. Because of the significant changes of the reduction of maximum load values and the wear for spot-bonded FRCs, this technique needs further in vitro and in vivo tests before it can be performed routinely in clinical practice.

Development of ‘My Retainers’ mobile application: Triangulation of two qualitative methods

ObjectiveDiligent wear of removable orthodontic retainers requires prolonged adherence and is invariably necessary to preserve optimal results. Patient-informed behaviour-change interventions represent a promising and novel means of enhancing adherence to removable retainer wear. The aim of this study was to describe the development of a patient-informed mobile application designed to enhance retainer wear. MethodsApp development encompassed consideration of participant preferences, social media posts, available interventions and behaviour change theories. Qualitative methods including analysis of publicly-available retainer-related posts on Twitter (n = 827) and one-to-one interviews were undertaken. Audio-recorded one-to-one interviews were undertaken to identify patient preferences in relation to features, content and design of the application. A criterion-based purposive sample of participants wearing vacuum-formed retainers for at least 4 years was used (n = 15). Thematic analysis of transcribed data was undertaken. These data were triangulated to inform design and content of the application. ResultsThe need to facilitate communication with the treating clinician, responsive reminder and tracking systems, and access to useful and engaging written and visual information, in addition to other personalised and interactive features were considered important. Concerns related to retainer wear shared on Twitter informed an exhaustive list of frequently-asked questions. Application features were mapped to relevant theoretical constructs. Determinants of existing behavioural change theories were also used to link application features to retainer wear and maintenance. ConclusionsA holistic process involving both patient and professional input can be useful in informing the development of mobile applications. The orthodontic application ("My Retainers") will undergo further scrutiny in relation to its effectiveness in inducing behavioural change and concerning patient experiences prior to finalisation.

Quantitative Interpretation of Hydration Dynamics Enabled the Fabrication of a Zwitterionic Antifouling Surface.

In the medical industry, zwitterionic brushes have received significant attention owing to their antifouling effect that arose from their hydration ability. However, sufficient understanding of the hydration dynamics of zwitterionic brushes is required to fabricate the precisely controlled antifouling medical devices. In this paper, we successfully show that hydration, the interaction between water molecules and zwitterionic brushes, and its dynamics can be evaluated logically and quantitatively using (i) water contact angle, (ii) molecular dynamics simulation, and (iii) Raman spectroscopy. Based on the intuitive results on hydration, we precisely optimized the antifouling property of the model medical device, a removable orthodontic retainer, with various grafting efficiencies of 2-methacryloyloxyethyl phosphate choline. As a result, the model device reduced nonspecific adsorption of proteins and bacteria, indicating an improved antifouling effect, and also inhibited the formation of a biofilm. Furthermore, the device showed excellent physical properties desirable for application in the orthodontic field, meaning the balance between the antibacterial property and mechanical strength.

Fiber-reinforced composites in endodontic practice: a review

Fiber-reinforced composites (FRCs) are a group of non-metallic biomaterials characterized by good mechanical properties, such as high fatigue resistance and fracture toughness growing in popularity in several dental applications. FRCs are a combination of two materials: the reinforcing phase in the form of fibers, which are embedded into the other material, called the matrix phase. Factors influencing the properties of FRCs include fibre properties versus polymer matrix properties, impregnation of fibres in the resin, adhesion of fibres to the polymer matrix, quantity and direction of fibres, and location of the fibre-rich phase in construction. The most commonly used applications of FRCs are in removable dentures, minimally invasive fixed dental prostheses, periodontal splints, root canal posts, and orthodontic retainers. This article discusses in detail the applications of FRCs in endodontics, including root canal posts, reinforcement of restorative composites in restorations and core build-ups and splinting of teeth in dental trauma.

Evaluation of the effectiveness of a tailored mobile application in increasing the duration of wear of thermoplastic retainers: a randomized controlled trial.

The 'My Retainers' mobile application is a patient-informed intervention designed to enhance removable retainer wear and associated patient experiences during the retention phase. To evaluate the effect of receiving the 'My Retainers' application on objectively assessed thermoplastic retainer (TPR) wear time, stability, periodontal outcomes, patient experiences, and knowledge related to retainers. Eighty-four participants planned for removable retention with TPRs were assigned either to receive the 'My Retainers' application or to control not receiving electronic reminders during the 3-month period. Randomization was based on computer-generated random numbers and allocation was concealed using opaque, sealed envelopes. The primary outcome was objectively assessed retainer wear recorded using an embedded TheraMon® micro-electronic sensor. Secondary outcomes, including irregularity of the maxillary and mandibular incisors, plaque levels, bleeding on probing and probing depth, were assessed at baseline and 3-month follow-up; and analysed using a series of mixed models. Experiences and knowledge related to orthodontic retainers were recorded using questionnaires. The outcome assessor was blinded when possible. Receipt of the mobile application resulted in slightly higher median wear time (0.91 hours/day); however, this difference was not statistically significant (P = 0.56; 95% confidence interval [CI]: -2.19, 4.01). No significant differences were found between the treatment groups in terms of stability (P = 0.92; 95% CI: -0.03, 0.04), plaque levels (P = 0.44; 95% CI: -0.07, 0.03), bleeding on probing (P = 0.61; 95% CI: -0.05, 0.03) and probing depth (P = 0.79; 95% CI: -0.09, 0.07). Furthermore, similar levels of patient experiences (P = 0.94) and knowledge related to retainers (P = 0.26) were found. However, marginally better levels of knowledge were identified in the intervention group. No harms were observed. A relatively short follow-up period with the study confined to a single-center in a university-based hospital. Provision of the bespoke 'My Retainers' application did not lead to an improvement in adherence with TPR wear over a 3-month follow-up period. Further refinement and research are required to develop and investigate means of enhancing adherence levels. NCT03224481.

A 15-year follow up of an orthodontic treatment including a lower incisor extraction and keeping the maxillary canine-premolar transposition.

Lower incisor extraction is an effective option for treating lower anterior crowding in patients with a good facial profile, Class I molar occlusion, and narrow upper incisors. This report describes the successful treatment of an adolescent patient with lower anterior crowding and a transposed maxillary canine and premolar treated by extracting a lower incisor and keeping the transposed positions of the teeth. With the use of retainers, treatment results were stable up to the 2-year postretention visit. However, upon a 15-year postretention appointment, the fixed retainer had been removed and the removable retainer was no longer in use, which resulted in relapse of lower anterior alignment. Moreover, the transposed canine had extruded during this period, causing occlusal interference and gingival recession, as well as loss of tooth vitality, which indicates the importance of maintaining orthodontic retainers for long-term stable occlusion.

Comparative evaluation of salivary microbial levels and periodontal status of patients wearing fixed and removable orthodontic retainers.

The purpose of this study was to compare and evaluate salivary microbial levels and periodontal status in patients using a fixed lingual retainer, a removable vacuum-formed retainer, or a Hawley retainer after orthodontic treatment with fixed appliances. Forty-five patients who finished their orthodontic treatment with fixed appliances and were about to start the retention phase were randomly divided into the following 3 groups of 15 individuals each: the fixed lingual retainer group, the vacuum-formed retainer group, and the Hawley retainer group. Periodontal measurements, such as the plaque index, gingival index, probing depth, and bleeding on probing, were obtained at the following 4 time points: at debonding (T0) and 1week (T1), 5weeks (T2), and 13weeks (T3) after debonding. Saliva samples were collected 3 times in total: at T0, T2, and T3. A quantitative analysis for Streptococcus mutans and Lactobacillus casei was performed with the use of real-time polymerase chain reaction. The Kruskal-Wallis test and 1-way analysis of variance were used for the statistical comparisons of the groups. No statistically significant difference in salivary S mutans and L casei levels was found among the 3 groups (P>0.05). They showed no statistically significant differences in plaque index, gingival index, bleeding on probing, and probing depth values (P>0.05). All periodontal parameters showed statistically significant decreases from T0 to T3 in all 3 groups (P<0.001). The S mutans and L casei levels were decreased significantly from T2 to T3 in the lingual retainer and Hawley retainer groups, whereas they decreased significantly from T0 to T3 in the vacuum-formed retainer group. Fixed and removable orthodontic retainers do not differ in salivary S mutans and L casei levels and periodontal status. With all retainers, regardless of whether they are fixed or removable, oral hygiene improved after orthodontic treatment with fixed appliances.

3D-Printed Wearable Personalized Orthodontic Retainers for Sustained Release of Clonidine Hydrochloride.

Orthodontic retainers are wearable customizable medical devices for dental protection or alignment. Here, clonidine hydrochloride (CH)-loaded wearable personalized 3D printed orthodontic retainers were studied for local sustained-release of drugs. CH powders were mixed with PEG 4000, Tween 80, poly(lactic acid), and polycaprolactone.The mixturewas hot-melt extruded to form a filament that was 3D printed to a customizable original orthodontic retainer with the fused deposition modeling (FDM) method. The original retainer showed aburst release of CH in the early stage of thedissolutionprocess though asustained release appearedin the late stage. Thein vivo burst release of CH would lead to unexpected side effect. The original retainer was modified by coating with hydrophilicpolymers or washing with buffered solutions to obtain the coated or washed retainer. The coated retainer still showed a burst releasewhile the washed retainer showed an optimalsustained release. ManyCH microparticles existed on the surface of original retainers according to the scanning electron microscopic image so that the burst releasewas unavoidable. The hydrophilic polymer coating method did not change the releaseprofile because the polymer was also rapidly dissolved. However, most ofthe surface CH can be eliminated by washing so that the burst release dissappearedin the washed retainer. Furthermore, the simulated CH concentration-time profiles in the circulation of humans of thewashed retainer showed the stable and appropriate drug levels for more than 3days. Wearable personalized 3D printed drug-loaded orthodontic retainers are a promising drug-device for sustained release of drugs.

Fixed Orthodontic Retainers: A Review.

Orthodontic retention is defined as maintaining teeth in optimal aesthetic and functional position after treatment. Despite the necessity of retention phase and the factors influencing the stability of the teeth after orthodontic treatment was discussed by the orthodontist for a long time, it is accepted that a retention phase is essential for stability of orthodontic treatment results nowadays. Therefore, the application of a suitable retention method is important both for prevention of relapse after orthodontic treatment and for increasing patient satisfaction. Removable appliances had been used for many years for retention purposes. Later, fixed retainers were introduced to prevent relapse as having a number of advantages, such as better aesthetics, no need for patient cooperation, effectiveness, and suitability for lifelong retention. However, their need for precise bonding technique, fragility, and tendency to cause periodontal problems by weakening oral hygiene are some of their disadvantages.

Factors influencing adherence to vacuum-formed retainer wear: A qualitative study.

To explore factors influencing adherence to vacuum-formed retainer wear over a minimum period of four years. A qualitative study based on a randomised controlled trial assessing the effectiveness of orthodontic retainers. Institute of Dentistry, Queen Mary University of London. Fifteen participants wearing vacuum-formed retainers for at least four years. One-to-one semi-structured interviews were undertaken on a criterion-based purposive sample of participants wearing vacuum-formed retainers. The interviews were audio-recorded, transcribed verbatim and analysed using Framework Methodology. High self-reported levels of adherence in the early stages of retention were linked to a desire to maintain orthodontic outcomes and the negative perception of potential post-treatment changes. However, adherence typically reduced over time due to a combination of factors including the negative impact of retainers on quality of life and pragmatic issues related to retainer wear. Network support was found to be important in the short and long term, with instances of self-directed wear and negative beliefs concerning the importance of retainer wear and predisposition to post-treatment changes. Lack of follow-up appointments and immaturity of participants prompted independent decisions to cease retainer wear. Six key influencers of prolonged adherence with vacuum-formed retainer wear were identified. Future strategies to improve adherence should account for these while also being responsive to time elapsed since debond and patient age.

How standard deviation contributes to the validity of a LDF signal: a cohort study of 8years of dental trauma.

The aim of this cohort study was to document the potential of laser Doppler flowmetry (LDF) for diagnosing tooth vitality in traumatized teeth in a population of 88 referred patients with dental trauma over a period of 8years (2011-2018). The main reason to refer was tooth discoloration (26%), and the main trauma cause was a traffic injury (35%). Taking into account that referral for LDF is best given within the week after trauma, 66% of referrals were overdue. In 73% of cases, root canal treatment could be avoided, and in 65%, the presence of a fixed orthodontic retainer showed beneficial for pulp recovery. Data of 394 teeth were collected and submitted to multilevel modelling statistics. As a general conclusion, both LDF perfusion and concentration values proved to be highly reliable in the appreciation of tooth vitality. The difference of variability of standard deviation and range of LDF measurements involving intra-subject control teeth showed statistically significant in discriminating between vital and non-vital pulps. In non-vital teeth, the diagnostic combination of LDF, sensibility tests and peri-apical X-ray is advised.