In vitro splint rigidity evaluation - comparison of a dynamic and a static measuring method

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.

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

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Effects of different splinting times on surgically extruded teeth with a crown-root fracture: A randomized controlled trial

BACKGROUND/AIM

Clinical studies evaluating the splinting time for surgically extruded teeth with crown-root fractures are lacking. The aim of this study was to compare 2-week splinting versus functional splinting times after surgical extrusion.

MATERIAL AND METHODS

Children aged 8-13 years who presented with crown-root fractures were included. Surgical extrusion was performed, and teeth were splinted either for 2 weeks or until normal Periotest values were achieved (functional splinting time). The outcome measures were tooth mobility, tooth loss, root resorption, marginal bone resorption and ankylosis. Measurements were taken at baseline, weekly after splint removal, and after 1, 3, 6 and 12 months.

RESULTS

Nineteen patients were included in the analysis. Surgically extruded teeth splinted for 2 weeks showed significantly higher mobility directly after splint removal and at 1 month after splinting compared with the functional splinting time group. The mean differences for horizontal Periotest values were 14.96 (95% confidence interval: 8.52, 21.39) and 6.63 (95% confidence interval: 0.25, 13), respectively. The vertical Periotest values were 10.47 (95% confidence interval: 1.95, 18.99) and 4.81 (95% confidence interval: -1.57, 11.18), respectively. At the 3-, 6- and 12-month follow-up intervals, there were no statistically significant differences between the groups. One tooth in the 2-week splinting group was lost. None of the teeth had ankylosis, marginal bone resorption or root resorption.

CONCLUSIONS

Although both groups showed neither statistical nor clinically significant differences after 12 months, there was a significant difference immediately after splint removal, with greater tooth mobility in the 2-week splinting group. Thus, a functional splinting time (4-6 weeks) can be suggested for better healing and optimal stability to allow placement of the final restoration directly after splint removal.

Tooth Mobility Reproduction in Dental Material Research: A Scoping Review

Background:

Introducing tooth mobility simulation in laboratory studies can provide results with high accuracy and predictability.

Objectives:

This study aims to review in vitro methodologies replicating tooth mobility and provide a recommended approach for future laboratory models.

Methods:

Databases, such as PubMed, Cochrane Database of Systematic Review, BioMed Central and Chinese databases are searched, and twelve articles are included in the final review.

Results:

Simulation methods of tooth mobility involving socket enlargement, screw loosening, alveolar bone loss simulation and a combination approach are identified from the extracted data. The materials used in preparing artificial teeth, artificial sockets and periodontal ligament simulator are discussed with a focus on their limitations. The achieved degrees of mobility and the presence of the centre of rotation are also evaluated. A timeline of the review articles is constructed to understand the trend of the preferred methods in tooth mobility simulation.

Conclusion:

Future in vitro investigations can achieve clinical reliability, particularly for materials tested in the field of dental traumatology and periodontology, by recognising the importance of incorporating tooth mobility in laboratory studies. Improvised methods are proposed to ensure that potential laboratory models can resemble the actual oral environment.

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.

Use of a laser displacement sensor with a non-contact electromagnetic vibration device for assessment of simulated periodontal tissue conditions

A non-contact electromagnetic vibration device (NEVD) was previously developed to monitor the condition of periodontal tissues by assessing mechanical parameters. This system requires placement of an accelerometer on the target tooth, to detect vibration. Using experimental tooth models, we evaluated the performance of an NEVD system with a laser displacement sensor (LDS), which does not need an accelerometer. Simulated teeth (polyacetal rods) were submerged at various depths in simulated bone (polyurethane or polyurethane foam) containing simulated periodontal ligament (tissue conditioner). Then, mechanical parameters (resonant frequency, elastic modulus, and viscosity coefficient) were assessed using the NEVD with the following detection methods: Group 1, measurement with an accelerometer; Group 2, measurement with an LDS in the presence of the accelerometer; and Group 3, measurement with an LDS in the absence of the accelerometer. Statistical analyses were performed using nonparametric methods (n = 5) (P < 0.05). The three mechanical parameters significantly increased with increasing depth. In addition, the mechanical parameters significantly differed between the polyurethane and polyurethane foam models. Although Groups 1 and 2 did not significantly differ, most all mechanical parameters in Group 3 were significantly larger and more distinguishable than those in Groups 1 and 2. The LDS was more accurate in measuring mechanical parameters and better able to differentiate periodontal tissue conditions. (J Oral Sci 58, 93-99, 2016).