Orthodontic Retention : Why When and How?

Direct 3D-Printed Orthodontic Retainers. A Systematic Review

Three-dimensional (3D) printing technology has shed light on many fields in medicine and dentistry, including orthodontics. Direct 3D-printed prosthetics, implants or surgical devices are well-documented. The fabrication of orthodontic retainers using CAD technology and additive manufacturing is an emerging trend but the available data are scarce. The research approach of the present review included keywords in Medline, Scopus, Cochrane Library and Google Scholar up to December 2022. The searching process concluded with five studies eligible for our project. Three of them investigated directly 3D-printed clear retainers in vitro. The other two studies investigated directly 3D-printed fixed retainers. Among them, one study was in vitro and the second was a prospective clinical trial. Directly 3D-printed retainers can be evolved over time as a good alternative to all the conventional materials for retention. Devices that are 3D-printed are more time and cost efficient, offer more comfortable procedures for both practitioners and patients and the materials used in additive manufacturing can solve aesthetic problems, periodontal issues or problems with the interference of these materials with magnetic resonance imaging (MRI). More well-designed prospective clinical trials are necessary for more evaluable results.

Survival analysis of three types of maxillary and mandibular bonded orthodontic retainers: a retrospective cohort

BACKGROUND

Retention is an important aspect of orthodontic treatment. This study aimed to analyze the survival of three types of maxillary and mandibular bonded orthodontic retainers.

METHODS

This retrospective cohort study evaluated the records of 118 orthodontic patients (90 females, 28 males, mean age of 22.34 ± 6.44 years) retrieved from a private orthodontic office. Data regarding the retainer failure, dental caries, unwanted tooth movements, maximum pocket depth (PD), and bleeding on probing (BOP) recorded at the follow-up sessions were extracted from patient records. Three types of retainer wires namely Bond-A-Braid, Orthoflex, and Retainium were compared regarding the abovementioned parameters. Data were analyzed by ANOVA, Chi-square, Monte-Carlo Chi-square, and Kruskal Wallis tests, the log rank test, and the Cox regression model.

RESULTS

The frequency of retainer failure was not significantly different between males and females, different age groups, or different treatment durations (P > 0.05). Wire fracture was the most common failure type in both the maxilla and mandible. Also, the frequency of failure was not significantly different between the maxillary and mandibular retainers (P > 0.05). The frequency of failure, and survival of the three types of retainer wires were not significantly different during a 5-year period (P > 0.05).

CONCLUSIONS

The three types of orthodontic retainers had comparable survival rates. Their failure rate was not correlated with the age or gender of patients or the treatment duration.

Retention Protocols and Factors Affecting Retainer Choice among Iraqi Orthodontists

Background

To identify the most common retention protocols practiced by Iraqi orthodontists using a specially designed e-survey. Furthermore, this study aimed to assess the effect of sociodemographic factors on the participant's choice.

Methods

Two hundred and twenty-five questionnaires with 23 multiple choice questions were sent to members of the Iraqi Orthodontic Society. The questionnaire was organized into four sections representing information about sociodemographic status of the orthodontists, factors affecting the selection of the retention system, commonly used retainers in the upper arch and lower arch, and duration of the retention system. The chi-square test was used to test the significant association between different variable and sociodemographic factors.

Results

The response rate was 87.5%. The majority of the respondents considered the original malocclusion (80.2%) and clinical experience (49.7%) as the main factors for choosing the retention protocol. In the maxillary arch, a combination of vacuum-formed retainer and fixed retainer (35%) was mostly applied; in the mandibular arch, a fixed retainer was mainly used (46.7%). Most of the respondents recommended initial full-time wearing of a removable appliance (78.2%), especially in the first 3-6 months (47.2%). According to the respondents, bonding a fixed retainer to all anterior teeth was most common (79.7%), fabricated, and adapted directly inside the patient's mouth (75.1%). More than half used flowable composite (54.8%) and recommend leaving the retainer forever (53.8%). Most of the variables showed a statistically significant association between the sociodemographic factors and type, duration, and fabrication of the retainer used.

Conclusions

A combination of removable and fixed retainers was commonly used in orthodontics retention, and sociodemographic factors significantly affected retainer choice.

Occlusal contact area changes with different retention protocols: 1-year follow-up

INTRODUCTION

The purpose of this study was to evaluate the occlusal contact area and cast-radiograph evaluation (CRE) score changes in patients with 3 different retention protocols after a 1-year retention period.

METHODS

A total of 90 patients with acceptable final occlusion according to American Board of Orthodontics CRE were equally divided into 3 groups according to the retention protocol: upper bonded retainer and lower Essix or bonded retainer (Essix group); upper bonded retainer and Hawley or lower bonded retainer (Hawley group); and upper bonded retainer and lower bonded retainer (bonded retainer group). Digital models were used to assess occlusal contact area changes after a 1-year retention period. The follow-up occlusion models were assessed with the American Board of Orthodontics CRE.

RESULTS

Occlusal contact areas increased significantly in the Hawley and bonded retainer groups for all teeth except incisors. The bonded retainer group showed the greatest amount of settling, but differences with the Hawley group were not statistically significant. However, statistically significant decreases in occlusal contact areas were recorded for the Essix group except for incisors. A decrease of CRE scores was seen in the Hawley group, whereas a statistically significant increase was recorded in the Essix group.

CONCLUSIONS

Both Hawley and bonded retainers allowed settling of the occlusion during the retention phase, whereas the Essix retainer did not allow relative vertical movement of the posterior teeth. The Hawley group showed improvement in the total CRE score, whereas the Essix group showed worsening.