Biomechanical effects of splint types on traumatized tooth: a photoelastic stress analysis

Effect of wire diameter and extent of wire composite splint on the mobility of luxated and anchor primary teeth: A typodont study

BACKGROUND/AIMS

The recommendations for splinting are well established for the injuries of permanent dentition; however, ambiguity still exists for the injuries in primary dentition. Hence, this study aimed to determine the most appropriate dimensions of stainless steel wire and its extent, for achieving the physiologic mobility in primary dentition.

MATERIAL AND METHODS

This study was designed as an in vitro experiment by using a typodont model of primary dentition. The baseline mobility of primary maxillary incisors was calibrated to the physiologic mobility of natural primary incisors by using a Teflon tape wrapped around the roots of resin teeth. Splinting was done using a stainless steel wire of 0.2 mm (Group I), 0.3 mm (Group II), and 0.4 mm (Group III). These groups were subdivided (a, b, and c) on the basis of the extent of the splint, and pre splint mobility (Pre-PV) and post-splint mobility (Post-PV) were tested by Periotest M. The splint effect was calculated by subtracting Post-PVs and Pre-PVs.

RESULTS

The normal values of mobility in healthy human volunteers ranged from 10.5 to 13. The overall splint effect was higher in Group III irrespective of the extent of the splint, whereas it was found to be the lowest in Group I (b and c). The splint effect increased with the extent of the splint in all the groups. Among all the groups, the splint effect on the anchor teeth was observed to increase with the extent of the splint and the diameter of the wire.

CONCLUSION

The mobility of the injured and anchor teeth splinted with 0.2-mm stainless steel wire was similar to the pre-splint and physiologic mobility. The most favorable extension was one tooth adjacent to the injured tooth on each side for both 0.2- and 0.3-mm wires.

Comparison of two composite resin materials for splinting of dental luxation injuries: A double blind randomized controlled trial

BACKGROUND/AIM

Luxation is a common traumatic dental injury treated with a wire composite (WC) splint. However, bulk-fill flowable composite and conventional packable composite have not been compared for retaining these splints. Therefore, the objectives of this randomized controlled trial were (1) to compare retention of WC splints, and (2) to compare adhesive point dimension, application and removal time, and effect on tooth mobility between the two WC splints.

MATERIALS AND METHODS

In this parallel group, non-inferiority double blind randomized controlled trial, a total of 90 patients, aged 16-50 years participated. They were randomly allocated into two groups, the packable composite group (PC) n = 45 and the bulk-fill flowable composite group (BF-FC) n = 45 by lottery method. Following measurements were taken at the splint application appointment. Horizontal tooth mobility measured via Periotest, splint application time, and frontal images of splinted teeth to measure the percentage composite adhesive point area. After 2 weeks, splints were visually inspected for retention, whereas mobility and removal times were also recorded. Statistically, comparisons were made using independent samples sample T-test, Fisher's exact test, and Mann-Whitney U at p ≤ .05.

RESULTS

A total of 88 patients with 156 luxated teeth completed the trial, as two patients were lost to follow-up. Two patients in the PC group reported with completely de-bonded splints while none de-bonded in the BF-FC group. Both groups were similar in terms of splint retention (p = .352), reduction of mobility (p = .426), and splint removal times (p = .372). The BF-FC group performed significantly better in adhesive point dimension percentages (p < .001) and splint application time (p < .001).

CONCLUSION

Both groups were comparable in most parameters of the study. However, for BF-FC group application time and adhesive point dimension were significantly less.

Splint stiffness and extension effects on a simulated avulsed permanent incisor-A patient-specific finite element analysis

BACKGROUND/AIM

Splinting is an important procedure after avulsion. However, the role of splint stiffness and extension is not fully understood. The aim of this study was to evaluate the effect of splint stiffness and extensions on the mobility and stress on an injured tooth under physiological biting load.

MATERIALS AND METHODS

Three-dimensional (3D) finite element models were created from a cone beam computer tomogram of a patient with normal occlusion. An avulsion injury of the right central incisor was created with a 1000 N load application on the palatal of the injured tooth, causing increased socket width. Splints made from four materials were tested: 0.9 mm diameter wire-composite splint (WCS1), 0.4 mm diameter wire-composite splint (WCS2), 1.0 mm diameter nylon-composite splint (NCS), and a 2 mm high by 0.2 mm thick plastic strip composite splint (PSS). Three splint extensions (involving 6, 5, and 3 teeth) were evaluated. Mobility of the avulsed tooth and the maximum principal stress distributions in the adjacent teeth were calculated.

RESULTS

The injured incisor tooth mobility was not affected by the splint extensions. The NCS and PSS stabilized the avulsed incisor but allowed, respectively, 10 and 20 times more mobility under horizontal loading than the WCS1, which inhibited most mobility, while the WCS2 allowed double the mobility compared with WCS1. The NCS and PSS allowed more tooth mobility, mainly in the extrusion direction. Splints were 2-3 times more effective in limiting mobility under intrusive loads than extrusive loads. High levels of stress were found at the base of the composite attachments in the adjacent incisors.

CONCLUSION

Splinting an avulsed tooth to one or two teeth bilaterally using a nylon splint or a plastic strip is appropriate for tooth stabilization and should be recommended over the 0.4mm wire-composite splint, while the 0.9 mm orthodontic wire is too rigid and not recommended.

Periodontal ligament repair after active splinting of replanted dogs' teeth

BACKGROUND/AIM

The high rate of root resorption resulting from tooth replantation represents a serious clinical problem. In order to prevent ankylosis and replacement resorption, the contemporary literature highlights the importance of using a flexible stabilization for traumatized teeth. For this purpose, orthodontic devices may be promising for obtaining a better prognosis and periodontal repair. The aim of this study was to evaluate the effect of an active splinting protocol with controlled force in dog's teeth following replantation.

MATERIAL AND METHODS

Sixty premolar roots from three dogs were used. They were submitted to endodontic treatment, hemisected, atraumatically extracted and subsequently replanted. They were divided into four groups: Passive Stabilization (n = 20)-after 20 min in a dry medium; Active Stabilization (n = 20)-after 20 min in a dry medium; Negative control (n = 10)-immediate replantation and passive Stabilization; and Positive control (n = 10)-90 min of extra-alveolar time and passive Stabilization. The samples were collected and submitted to histologic processing. They were then evaluated for the count of inflammatory cells, expression of neurotrophin 4, osteoclasts, apoptotic cells and collagen fibres. The results were submitted to ANOVA or Kruskal-Wallis statistical tests followed by Tukey or Dunn post-tests (α = 5%).

RESULTS

Passive Stabilization with orthodontic brackets without traction used after replantation had the highest number of inflammatory cells (p = .0122), osteoclasts (p = .0013) and percentage of collagen fibres in the periodontal ligament (p < .0001) when compared to Active Stabilization with orthodontic brackets applying amild tensile force. Neurotrophin 4 had no statistically significant difference (p = .05), regardless of the treatment. The apoptotic cells count revealed statistical differences (p < .0001) between Active Stabilization (189.70 ± 47.99) and Positive Control (198.90 ± 88.92) when compared to Passive Stabilization (21.19 ± 32.94).

CONCLUSION

The active splinting protocol using orthodontic appliances generating a light and controlled force favoured periodontal ligament repair of replanted teeth.

Use of Orthodontic Methods in the Treatment of Dental Luxations: A Scoping Review

(1) Background: Treating dental luxation injuries is challenging for the clinician. Dental luxations account for 18-33% of injuries to permanent teeth and can be addressed using different therapeutic approaches. The present work was conducted with two aims: (i) to evaluate, through a scoping review, current knowledge of the orthodontic methods (repositioning and stabilization splinting) that can be used at the time of the trauma, and (ii) to investigate the frequency and type of pulp consequences arising after these traumatic injuries. (2) Methods: The literature search was conducted in the period June 2020-December 2020 using the PubMed/MEDLINE, SCOPUS and Web of Science databases. The research questions were formulated according to the PICO (Population, Intervention, Comparison, Outcomes) method and considered the following aspects: type of luxation injury and stage of root development; use of orthodontic repositioning and splinting techniques; frequency and type of pulp consequences; and compliance of treatments with international guidelines. (3) Results: The initial screening of the databases, using the selected search keywords, yielded a total of 587 articles, just 8 fully met the inclusion criteria. Closer analysis of these 8 publications revealed that they would not produce clear meta-analytical data. This made it necessary to limit the data collected to the following six items: number and type of injuries, initial therapeutic intervention, duration of follow-up, number, and type of different pulp consequences. (4) Conclusions: While orthodontic techniques are commonly used to treat dental intrusions, in the case of extrusive and lateral luxation injuries, they are less frequently used and the orthodontic approach is generally confined to the stabilization phase. Among the various possible pulp consequences, many authors consider only pulp canal obliteration (PCO) and pulp necrosis (PN), often tending to overlook physiological healing (pulp survival) and the possible development of PN after PCO. There is therefore a clear need for new, high-quality clinical studies of this topic based on systematic and standardized data collection.

Influence of preoperative degree of tooth loosening and thickness of wire on the rigidity of wire composite splint

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Fractured alveolar process displacement evaluation-Effect of the rigidity of wire-composite splints

BACKGROUNDS/AIMS

Traumatic dental injuries with bone fractures require rigid splinting. The degree of rigidity of the wire-composite splints can be challenging. The aim of this study was to evaluate the effect of the rigidity of different wire-composite splints on alveolar process displacement.

MATERIAL AND METHODS

A model was created using polystyrene resin to simulate the anterior maxilla, bovine incisors to simulate maxillary incisors, and polyether impression material to simulate the periodontal ligament. An alveolar process fracture was created, while maintaining the labial bone connection with the PDL. Four wire-composite splints (0.3, 0.6, 0.9, and 1.2 mm in diameter) were compared with models without splints and with no fracture (n = 5). The alveolar process displacement was measured (3 times per model/per splint type) at the fractured and adjacent central incisor regions using a deflectometer (Instron) under functional cycling and static loading (100 N). Data (μm) were analyzed using RM ANOVA, followed by Tukey's HSD test (α = 0.05).

RESULTS

The displacement at the region of the adjacent incisor was not influenced by the splint during static and cycling load (P > .05). The Tukey test demonstrated that the model without splints had significantly higher alveolar process displacement at the traumatized teeth than that of all other splint models (P < .001). Increasing the wire diameter from 0.3 mm to 0.9 mm significantly reduced the alveolar process displacement (P < .001). No difference was observed between the 0.9 mm (P = .123) and 1.2 mm (P = .219) wire-composite splints irrespective of the measured tooth regions.

CONCLUSIONS

The rigidity of the wire-composite splint significantly influenced the mobility of the fractured alveolar process. The use of at least 0.9 mm wire was effective in reducing the fractured alveolar process displacement to a level that was similar to the adjacent teeth.

Photoelastic stress analysis of different types of anterior teeth splints

BACKGROUND/AIMS

Traumatic dental injuries are highly prevalent and are considered an important health problem. The aim of this study was to evaluate the in vitro stress distribution around simulated traumatized teeth subjected to different types of splints by photoelastic analysis.

MATERIALS AND METHODS

For each group, five models of maxillary and mandibular arches were made in photoelastic resin using prefabricated teeth models, which were fixed and adjusted in a semi-adjustable articulator. All splints were bonded with composite resin on the labial surfaces of the maxillary central incisors, the lateral incisors and the canine teeth, simulating trauma to the 11. The groups were divided according to the type of splint: control-without splint; rigid-brackets and 0.021 × 0.025 inch stainless steel wire; semi-rigid-brackets and 0.016 × 0.016 inch cobalt-chromium wire; fiber-fiberglass ribbon; and flexible-nylon thread. The groups were submitted to an occlusal force in a special device attached to a universal test machine in balanced, protrusive, and lateral occlusions. Then, the incisal edge of the 11 was ground to simulate infra-occlusion, and the tests were performed again. Five points were analyzed around tooth 11 with a polariscope, and the data were submitted to ANOVA and Tukey tests at a 5% level of significance.

RESULTS

When centric occlusion was analyzed by comparing normal occlusion to infra-occlusion, all groups showed high stress values in infra-occlusion with statistical differences-except for the control group. When lateral occlusion was analyzed, the nylon splint showed lower statistical differences compared with the control, fiberglass, and rigid splint groups, which did not differ between each other. The semi-rigid splint did not differ from any group.

CONCLUSIONS

Fiberglass and semi-rigid splints showed better stress distribution around the traumatized tooth under occlusal loads. The nylon splint showed characteristics of non-stress distribution.

Dentoalveolar Fractures: New Orthodontic Protocol Proposal and Pilot Study

The goal of fracture treatment that includes the dentoalveolar process is to obtain the anatomic bone healing and the pre-injury occlusion restoration with functional and aesthetic recovery, avoiding dental or periodontal lesions. Fractures activates, in the damaged tissue, the Regional Acceleratory Phenomenon, a physiological healing process that can also be activated during orthodontic overloads. Orthodontic treatment in the traumatized area could exploit this phenomenon in order to sustain the cellular activity.The aim of this study is to propose a treatment protocol for dentoalveolar fractures based on the use of orthodontics in order to sustain the physiological healing process known as Regional Acceleratory Phenomenon.The authors present 2 cases of an 18 year old woman and 23 year old man affected by dentoalveolar fracture. The operative protocol the authors applied foresaw three steps of treatment: orthodontic brackets application, surgery, orthodontic treatment.The patients showed complete healing at the 3 months follow-up and were treated up to 18 months for further orthodontic treatment.The operative protocol proposed by the Authors appears to be a rational choice since it allows a single orthodontic device to be an "active splinting system", with fast application time, good acceptance by the patient, low complications rate; moreover, it produces any planned dental movements for further orthodontic treatments.

A digital technique for splinting periodontally compromised mobile teeth in the mandibular anterior region

A digital technique for fabricating a periodontal splint is presented. The lingual surface of periodontally compromised mandibular anterior teeth is captured and registered to form the emergence profile of the periodontal splint. An accurate periodontal splint is fabricated for mandibular anterior teeth with increased mobility after scaling and root planing.

Best Splinting Methods in Case of Dental Injury-A Literature Review

The objective of this manuscript was to review the literature on dental trauma splints and discuss materials used for splinting injured teeth in terms of their properties and conditions that are required for optimal stabilization. A literature search was conducted in the PubMed database with the keywords: "trauma splints", "dental trauma" and "traumatic dental injuries". The search was limited to English language publications. 42 publications fulfilled the inclusion criteria and were in accordance with the current recommendations. Optimal splinting of the teeth after trauma is one of the main predictors for pulpal and periodontal healing. The splints stabilize and protect the teeth, creating favorable conditions for the regeneration of the supporting tissues. Their application and removal should be easy and fast without any additional irritating of the surrounding tissues. The materials used to stabilize the injured teeth should keep the tooth in the original position, allowing for its physiological mobility.

Photoelastic analysis of stress distributions in the root-bone interface when applying various orthodontic methods to subside lower anterior crowding

Dental crowding is a prevalent problem in modern society. Various factors, including different bracket systems and geometry of wire, influence the outcome using superelastic wire in the alignment stage of treatment. Currently, the use of light round wire instead of large-sized rectangular wire is emphasized to avoid powerful torsional stiffness. However, these guidelines lack scientific evidence for support. They have been written predominantly based on clinical experience. Therefore, the purpose of this study was to evaluate how factors such as bracket systems and wire geometry affect the stress distribution at the root-bone interface. Models using a photoelastic material (PL-3) to simulate bone tissue were fabricated. The simulated teeth were arranged as in lower anterior crowding. Then, the crowded teeth were subjected to orthodontic treatment with various types of bracket, ligating approaches using ligature wires of different sizes, shapes, and materials. Photoelastic images of the bone area of the models were obtained and compared. The results showed that wire size plays a more significant role than the material or cross-sectional shape of the wire in affecting the stress distribution at the simulated root-bone interface. The teeth ligated with a larger cross-sectional diameter of wire showed the application of excessive torque, which may cause root resorption and slow down tooth movement. These results not only demonstrate the scientific evidence backing clinical experience but also can be a useful reference for further clinical application.

Establishment of experimental models to evaluate the effectiveness of dental trauma splints

The purpose was to describe a novel simple experimental model of injured teeth for developing dental trauma splints (DTS), and to test various splints by combining use of this model and the Periotest^® device. Rubber O-rings and spring washers were used to simulate and modify injured tooth mobility. Splinting effects were assessed among three kinds of DTS, including a composite splint and two wire-composite splints (1: rectangular orthodontic wire 0.533×0.635 mm, 2: cobalt-chromium alloy wire Φ0.9 mm). The Periotest values were measured three times for each tooth before and after splint insertion. The splinting effect was defined as the change in tooth mobility. Splinting effects significantly increased in the order wire-composite splint 1<wire-composite splint 2<composite splint (p<0.05). This model system could evaluate the effects of DTS including the differences among various splint methods, which showed reasonable reproducibility of dental trauma situations depending on severity in clinical usage.

Orthodontic treatment of a mandibular incisor fenestration resulting from a broken retainer

This article describes the orthodontic relapse with mandibular incisor fenestration in a 36-year-old man who had undergone orthodontic treatment 21 years previously. The patient reported that his mandibular 3 × 3 bonded retainer had been partially debonded and broken 4 years earlier. The mandibular left lateral incisor remained bonded to the retainer and received the entire load of the incisors; consequently, there was extreme labial movement of the root, resulting in dental avulsion. As part of the treatment, the root was repositioned lingually using a titanium-molybdenum segmented archwire for 8 months, followed by endodontic treatment, an apicoectomy, and 4 months of alignment and leveling of both arches. The treatment outcomes were excellent, and the tooth remained stable, with good integrity of the mesial, distal, and lingual alveolar bones and periodontal ligament. The 1-year follow-up showed good stability of the results.

Stress distribution in delayed replanted teeth splinted with different orthodontic wires: a three-dimensional finite element analysis

AIM

The aim was to evaluate the biomechanical behavior of the supporting bony structures of replanted teeth and the periodontal ligament (PDL) of adjacent teeth when orthodontic wires with different mechanical properties are applied, with three-dimensional finite element analysis.

MATERIALS AND METHODS

Based on tomographic and microtomographic data, a three-dimensional model of the anterior maxilla with the corresponding teeth (tooth 13-tooth 23) was generated to simulate avulsion and replantation of the tooth 21. The teeth were splinted with orthodontic wire (Ø 0.8 mm) and composite resin. The elastic modulus of the three orthodontic wires used, that is, steel wire (FA), titanium-molybdenum wire (FTM), and nitinol wire (FN) were 200 GPa, 84 GPa, and 52 GPa, respectively. An oblique load (100 N) was applied at an angle of 45° on the incisal edge of the replanted tooth and was analyzed using Ansys Workbench software. The maximum (σmax) and minimum (σmin) principal stresses generated in the PDL, cortical and alveolar bones, and the modified von Mises (σvM) values for the orthodontic wires were obtained.

RESULTS

With regard to the cortical bone and PDL, the highest σmin and σmax values for FTM, FN, and FA were checked. With regard to the alveolar bone, σmax and σmin values were highest for FA, followed by FTM and FN. The σvM values of the orthodontic wires followed the order of rigidity of the alloys, that is, FA > FTM > FN.

CONCLUSION

The biomechanical behavior of the analyzed structures with regard to all the three patterns of flexibility was similar.

Splinting--when and how?

The prognosis of a tooth following trauma is critical. This depends on various factors, including the type of splint used for immobilization and the immobilization period. This article discusses the above factors with an added note on splint removal.

CLINICAL RELEVANCE

This article is relevant for clinicians who treat traumatic injuries as it should help them to decide on the type of splint to be used and the period of immobilization.

Management of subluxation injury in a thumb-sucking child: a case report

This case report presents use of a custom trauma splint that was fabricated to prevent excessive thumb-sucking trauma to a previously-subluxated permanent incisor. A 10-year-old boy was referred to the clinic 10 days after falling in the schoolyard that resulted in a trauma to his maxillary left central incisor. The extent of clinical mobility stipulated fabrication of a custom trauma splint that would prevent further trauma to the incisor caused by excessive pressure of the thumb. A light-cured resin composite splint, covering the incisal edges of the central incisors and labial surfaces of the lateral incisors was made, and approximately 1-mm composite within the impressions of central incisors were trimmed off. The splint was bonded to the neighboring lateral incisors with flowable resin composite and root canal therapy was initiated on the subluxated incisor. After one week, the patient stopped his sucking habit completely. The treatment not only allowed for complete healing of the subluxated incisor without being exposed to further trauma, but also for spontaneous eruption of the tooth and closure of the existing open-bite.