Shear Bond Strength of Four Types of Orthodontic Retainers after Thermocycling and Cyclic Loading

Comparative evaluation of the performance of orthodontic retainers using different surface protocols: an in vitro study

This study aims to assess the in vitro durability of Nitinol retainers, manufactured using computer-aided methods with hydrophilic or superhydrophilic surfaces to reduce debonding, alongside a commonly used composite adhesive. The 112 lower incisor teeth were embedded in blocks in pairs. Retainer wires were made up of 0.018 × 0.018 inch Nickel Titanium alloy(G4™ Nickel Titanium G&H Orthodontics, USA) by bending a robot arm. A total of 16 teeth(8 blocks) were used for each of the mentioned 7 groups Ni-Ti Retainer; Laser Textured Ni-Ti Retainer; Laser Texturing and Atmospheric Plasma Applicated Ni-Ti Retainer; Atmospheric Plasma Applicated Ni-Ti Retainer; Laser Texturing and Atmospheric Plasma Applicated Ni-Ti Retainer*2; Laser Texturing and Atmospheric Plasma Applicated Ni-Ti Retainer*3; SS-0.0018"(Morelli, Brazil). Transbond LR(3 M Unitek, California) was used. The shear bond strength tests were conducted. The Kruskal-Wallis H test was employed, pairwise comparisons followed by Dunn's test with Bonferroni correction as a post-hoc analysis. There was no statistically significant difference between the groups for maximum force and maximum stress(p > 0.05). However, a significant difference was found in maximum elongation (p:0.0023). Pairwise comparisons highlighted significantly higher elongation values in the SS-0.0018" group. The stainless-steel wire demonstrated higher elongation values, which may offer clinical advantages in cases with higher occlusal forces and periodontal problems due to its material flexibility. Laser Texturing and Atmospheric Plasma Applied Ni-Ti Retainers exhibited higher test performance. Surface treatments applied to CAD/CAM retainers can provide an advantage by enhancing bond strength, potentially reducing the risk of debonding. These findings underline the importance of material selection and surface treatments in optimizing fixed retention strategies for long-term clinical success.

Does relative bracket base area affect the accuracy of reconstructed buccal surface in the virtual bracket removal technique?

BACKGROUND

Virtual bracket removal (VBR) facilitates efficient retainer fabrication for fixed orthodontics in a digital workflow. This study is aimed at assessing the influence of the relative bracket base area (RBA), representing the proportion of the labial/buccal surface area intended for removal, on the surface reconstruction accuracy in the VBR technique.

METHODS

196 teeth from seven resin dental models were included. The maximal bracket base surface area (MBA) was determined by the rectangular area extending to the lateral edges of the tooth labial/buccal surface. On each tooth, diverse RBA percentages (20-100% in 10% increments) of the MBA was removed, respectively. Following removal, the buccal surfaces of the teeth were digitally reconstructed. Subsequently, the root mean square (RMS) values, which represent the surface deviations between the reconstructed and original dentitions was calculated for each tooth. The obtained RMS values were compared within and among groups of different RBAs and compared with the clinically acceptable limit (CAL) of 0.05 mm.

RESULTS

As the RBA increased, there was a discernible trend of elevated RMS values, both for the overall dentition and each specific tooth type. Among the lower teeth, the molars consistently displayed the highest RMS values in almost all groups, with significantly higher mean/median RMS values compared to the lower incisors (P < 0.05), excluding the 0.2MBA group. Specifically, across all tooth types, the mean/median RMS values in groups with 20-80% MBA were significantly lower than CAL of 0.5 mm (P < 0.05). This trend persisted for all tooth types in the 0.9MBA group except the lower canines and molars.

CONCLUSION

The mean/median RMS values elevated as the RBA increased. VBR technique remains sufficiently accurate for retainer fabrication, provided that the RBA remains below 80% of the MBA for lower canines and molars and 90% for all the other tooth types. Notably, residual bonding materials should be considered in clinical use because they are also removed in VBR and thereby constitute a portion of RBA.

Different Wire Surface Treatments on Adhesion Efficacy of Orthodontic Fixed Retainer: An In Vitro Study

AIM

This study assesses the impact of surface treatment with sandblasting and Z-primer on the adhesion efficacy of fixed lingual retainers.

MATERIALS AND METHODS

Dead soft stainless steel wire 0.016 × 0.022-inch (n = 120) was treated by different techniques and classified into four groups equally (n = 30) according to surface treatment. Group I wire without treatment, group II wire treated with sandblasting, group III wire treated with Z-primer alone, and group IV wire treated with sandblasting with Z-primer. The stainless steel wire (n = 40) was bonded to 80 extracted premolars in pairs mounted in acrylic. Other stainless steel wires (n = 80) are embedded into acrylic blocks. All groups were divided into two subgroups according to thermocycling teeth samples were assessed by shear bond strength (SBS) A stereomicroscope was used to calculate the adhesive remnant index (ARI), while the acrylic block was by pull-out test. Finally, data were analyzed by IBM-SPSS (V 27, 2020). Mann-Whitney U-test; Kruskal-Wallis H-test and, two-way ANOVA were utilized to assess for SBS and pull-out.

RESULTS

Kruskal-Wallis H-test showed a non-significant difference in ARI between all groups, while in two-way mixed ANOVA demonstrated a significant difference in SBS between group III (sandblasting/Z-primer) vs group I and group IV Z-primer (p = 0.028) and control (p = 0.016), and a significant difference between group II sandblasting vs both group I and group IV Z-primer (p = 0.024) and control (p = 0.014). The two-way mixed ANOVA tests showed a significant difference in pull-out between sandblasting/Z-primer vs Z-primer (p = 0.012).

CONCLUSION

Using of mixed surface treatment for fixed retainer as sandblasting with Z-primer is considered as the best method to increase adhesion efficacy between wire and composite and improve the quality of orthodontics fixation when compared with single treatment (sandblasting alone or Z prime). On the other hand, the sue of sandblasting alone for fixed retainer surface treatment is better than Z-primer alone but both treatments are better than fixed retainer without treatment.

CLINICAL APPLICATION

Developed and examined new and traditional techniques used to treat the surface of wire used as a retainer after orthodontics treatment to improve patients' treatment and life quality and decrease the chance of relapse. How to cite this article: Naji SM, Mohammad MH, Enan ET, et al. Different Wire Surface Treatments on Adhesion Efficacy of Orthodontic Fixed Retainer: An In Vitro Study. J Contemp Dent Pract 2024;25(7):677-683.

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.

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.

Comparison of microleakage and shear bond strength of ribbon and twisted wire retainers bonded on human mandibular incisors with two different types of adhesives with and without primer: An in-vitro study

BACKGROUND AND OBJECTIVES

Shear bond strength and microleakage are the success factors of fixed retainers. Recently, primer-free composites were introduced to reduce chair time. The main objectives of this study were to compare the shear bond strength (SBS) and microleakage of GC Ortho Connect^TM Flow (OF) and Transbond^TM XT (TXT) with two types of common retainer wires (0.0175-inch twisted wire and 0.028×.0.008-inch ribbon dead soft wire retainers). The secondary objectives of the study were to compare enamel-adhesive interface and wire-adhesive interface microleakages.

MATERIALS AND METHODS

This in vitro study was conducted on 132 human mandibular incisors (96 for bond strength and 36 for microleakage). The teeth were randomly divided into four groups for use of ribbon and twisted wires with OF and TXT adhesives. The bond strength was measured by a universal testing machine. Microleakage was evaluated by the dye penetration test using 0.05% fuchsine. Data were analysed by two-way ANOVA (alpha=0.05).

RESULTS

No significant difference was noted in bond strength among the four groups (P>0.05). However, the microleakage of OF was significantly higher than that of TXT at both the enamel-adhesive and wire-adhesive interfaces (P<0.001). The microleakage at the wire-adhesive and enamel-adhesive interface was not significantly different in groups 1 and 4 and was significant in group 2 and 3.

CONCLUSION

Type of adhesive significantly affected the microleakage, and OF resulted in higher microleakage than TXT at both the enamel-adhesive and wire-adhesive interfaces. Type of wire had no significant effect on microleakage. Although OF showed comparable SBS to TXT, its higher microleakage may compromise its successful long-term clinical service.

Bruxism’s Implications on Fixed Orthodontic Retainer Adhesion

Background: Fixed retainers assist in maintaining the outcomes of orthodontic treatment. Fixed retention may be affected by bruxism. Objective: Evaluate two adhesives (an ormocer and a flowable composite) used for fixed orthodontic retention in simulated bruxism settings, compared to regular mastication, using a dual axis chewing simulator. Methods: Eighty human teeth were used. Periodontal tissues were simulated and exposed to 120,000 mechanical cycles, corresponding to 6 months of clinical service. Each set of two teeth was supplied with a pre-shaped, fixed, multi-braided, stainless steel wire retainer, in 1.5 cm portions, to establish passive contact with the lingual surface of the teeth. The Adhesive Remnant Index (ARI) was used to evaluate the shear bond strength. A stereomicroscope was used to assess the micro-infiltration. Results: There was no significant difference in the mean value of micro-infiltration between adhesives in the mastication group but in the bruxism group. During testing, one composite sample (ARI score 1) was broken in the mastication group, while three ormocer samples (ARI score 2) and one composite sample (ARI score 1) were broken in the bruxism group. Conclusions: The mean value for micro-infiltration in composite (0.31) was more than double that in ormocer (0.13).