ORIGINAL RESEARCH

https://doi.org/10.5005/djas-11014-0054
Dental Journal of Advance Studies
Volume 12 | Issue 3 | Year 2024

Fracture Resistance of Reattached Teeth: In Vitro Evaluation of Various Reattachment Techniques

Ankita Agrawal1https://orcid.org/0009-0009-2065-0944, Sandhya K Punia2https://orcid.org/0009-0004-1765-8412, Yogender Kumar3https://orcid.org/0009-0002-4699-3792, Shilpi Kushwaha4https://orcid.org/0009-0002-9034-7261, Deepak Sharma5

1–5Department of Conservative Dentistry and Endodontics, Darshan Dental College & Hospital, Udaipur, Rajasthan, India

Corresponding Author: Sandhya K Punia, Department of Conservative Dentistry and Endodontics, Darshan Dental College & Hospital, Udaipur, Rajasthan, India, Phone: +91 9660987078, e-mail: drsanvikpunia@gmail.com

How to cite this article: Agrawal A, Punia SK, Kumar Y, et al. Fracture Resistance of Reattached Teeth: In Vitro Evaluation of Various Reattachment Techniques. Dent J Adv Stud 2024;12(3):145–149.

Source of support: Nil

Conflict of interest: None

Received on: 24 June 2024; Accepted on: 15 August 2024; Published on: 31 December 2024

ABSTRACT

Aims and background: Fragment reattachment remains a preferred conservative treatment, offering a balance between esthetic recovery, patient satisfaction, and functionality. Understanding the reattachment technique options helps clinicians provide the best care tailored to individual cases.

Materials and methods: Thirty permanent maxillary central incisors were mounted in acrylic resin and divided into 3 groups (n = 10) based on reattachment methods: Group A (Control), group B (Chamfer), group C (Overcontouring). Standardized crown fractures were simulated and reattached using a light-curable flow able composite. The specimens were stored, thermocycled, and tested for fracture resistance.

Results: Intact teeth (Control) showed the highest fracture resistance (372 ± 17.45 N). Among reattached teeth, overcontouring (295.9 ± 24.00 N) performed best, followed by Chamfer (170.2 ± 28.39 N).

Conclusion: None of the reattachment techniques matched the fracture resistance of intact teeth. Overcontouring yielded the best results, while the Chamfer technique is not recommended due to its low fracture resistance.

Clinical significance: By understanding the strengths and limitations of various reattachment techniques, clinicians can make informed decisions to optimize both functional and esthetic outcomes for patients with anterior tooth fractures.

Keywords: Chamfer, Fracture resistance, Overcontour preparation, Tooth fragment reattachment.

INTRODUCTION

Injuries to the teeth are prevalent among children and adolescents, often resulting from their engagement in contact sports, conflicts at home, unintentional falls, participation in dangerous activities, and an increase in traffic accidents. Studies indicate that children between the ages of 8 and 11 are particularly prone to fractures of their front teeth. Specifically, coronal fractures of permanent incisors represent a significant portion, estimated at 18–22%, of all hard tissue injuries. Remarkably, 96% of these injuries affect the upper incisors, with central incisors involved in 80% of the cases and lateral incisors in 16%.1 Traumatic dental injuries (TDIs) are recognized as highly disruptive and distressing emergencies within dental practices. These incidents not only inflict damage on the dental structure but also carry a substantial psychological effect on the patient.2

Uncomplicated fractures affect only enamel and enamel-dentin, while “complicated” ones reach the enamel-dentin-pulp area. Crown fractures need urgent attention, whether uncomplicated or complicated. Emergency care should include covering exposed dentin or pulp with proper dressings to protect them, with restorative treatments to follow after sealing the injury.3 The challenge of restoring a simple coronal fracture is significant for dental practitioners, given the numerous factors that must be navigated to achieve a successful restoration. Essential considerations include the goal of producing an esthetically pleasing result that accurately resembles the natural shape and size of the tooth, in addition to the original tooth’s qualities such as opacity, translucency, fluorescence, and opalescence.4

Several factors play a crucial role in the management of the coronal tooth fractures. These include the range of the fracture, which may compromise the biological width, involve the endodontic system, or affect the alveolar bone. The specific characteristics of the fracture and the viability of restoring the tooth, especially in the presence of a root fracture, are also important. Furthermore, considerations such as secondary trauma to the soft tissues, the presence of a fractured tooth fragment and its compatibility with the remaining structure, occlusal relationships, financial implications, and prognosis must all be taken into account in the overall management plan.5 In cases of coronal fracture, a dentist can provide multiple treatment alternatives, including the reattachment of the fractured segment, composite buildup, or the application of a full-coverage crown. The choice of treatment is influenced by the fracture’s position, its degree of severity, and the suitability of the fractured components. Additionally, the patient’s preferences play a crucial role in the final decision, as they consider the benefits and drawbacks of each approach.6

The treatment approaches for these fractures range from composite restorations to the application of intracoronal restorations. The definitive treatment pathway is influenced by the severity of the hard tissue fracture. However, these options frequently require the extraction of a healthy tooth to ensure adequate mechanical retention, which renders them both time-intensive and expensive. Furthermore, given the large size of pulp chambers and the continuous movement of the epithelial attachment, these treatment strategies are generally inadvisable for adolescents.7 Despite substantial advancements in adhesive systems and composite resins, limitations persist, notably polymerization shrinkage, which can affect the longevity of the adhesive interface. This, along with the amount of dental structure removed during preparation, can reduce fracture strength, posing challenges for composite restorations. Nevertheless, the use of adhesive materials can partially or fully restore fracture strength, depending on the specific system and technique used.8

The process of crown fragment reattachment is widely acknowledged in the context of young adolescents. It is imperative for both parents and children to appreciate the importance of retrieving the lost fractured fragment and to ensure that it is stored correctly until the time of reattachment.7 In comparison to alternative methods, the reattachment technique for teeth provides a variety of advantages. It is often viewed as the most conservative procedure, as it allows for optimal esthetic restoration by ensuring the tooth’s hue, shape, surface finish, and transparency. Align with those of the biologic tooth. Furthermore, this technique shows similar color stability and wear characteristics to the adjacent teeth.9 If the fragment is available, it may be regarded as the first-line treatment option, contingent upon the fulfillment of necessary conditions such as an intact biological space. This method not only reinstates the biological and esthetic qualities of the natural tooth but also ensures its functionality, achieving a high success rate.10 Techniques such as Chamfer preparation and overcontouring improve fragment bond and contact area.

Hence, the purpose of the current study was to determine the fracture resistance of the tooth fragment reattached using Chamfer preparation and overcontouring techniques. The null hypothesis for this study proposed that different tooth preparation techniques do not affect the fracture resistance of reattached tooth fragments.

MATERIALS AND METHODS

Sample Selection

A total of thirty sound permanent max central incisor teeth selected for the study were cleaned of any debris, deposits and calculus using an ultrasonic scaler and were preserved in distilled water till their utilization. After cleaning, all the specimens were viewed under a stereo microscope to discard teeth with defects.

Specimen Grouping and Sectioning

The 30 incisors were grouped into 2 groups: 10 teeth for the control group (Group A: Intact Teeth) and 20 teeth for the experimental groups (Groups B and C) (n = 10 each).

The roots of the teeth were incorporated into a mass of acrylic resin, so only the crown of the tooth was visible. Experimental teeth were subjected to sectioning, 3 mm from the incisal edge parallel to it, utilizing a diamond disc. Sections were coded and stored at room temp. in artificial saliva.

Reattachment Procedures of the Specimen

The reattachment procedures for the teeth were followed for the test groups as mentioned below:

Group B (n = 10): Chamfer group, Chamfer was prepared extending 2 mm cervically on the tooth, 2 mm further than the edge of the fractured surface on the fractured fragment with a diamond point Fig. 1). Both parts of the specimen teeth were etched using 37% phosphoric acid, followed by thoroughly washing for 30–40 seconds and after which they were gently blot dried using a cotton pellet. The adhesive system was applied to both dental fragments with the help of a micro brush and was left undisturbed for 10–15 seconds followed by rubbing for 20 seconds. For a period of 5 seconds, the adhesive layer was subjected to air thinning to ensure the solvent’s evaporation. The adhesive layer was light-cured for 10 seconds using an LED light curing (Satelec) unit according to the instructions given by the manufacturer at an intensity 1000 mW/cm2 ensuring that the fragments remained apart. Digital pressure was utilized to reposition both dental fragments after the application of a thin layer of flow able nanocomposite. Material in excess was eliminated from both the buccal and lingual surfaces. Light curing was performed for 20 seconds both the palatal and labial surfaces. During the process of light curing, a certain amount of digital pressure was applied to the incisal dental fragment.

Figs 1A and B: Preparation of specimens for group B, (A) A line traced 2 mm on buccal surface and measured using a digital vernier caliper; (B) Chamfer preparation done using diamond point

Group C (n = 10): Prior to commencing the reattachment of the fractured fragments in the overcontouring group, the buccal surface was prepared using a cylindrical diamond finishing point. This preparation extended 2.5 mm, both coronally and apically, from the fracture line, achieving a depth of 0.3 mm Fig. 2). The adhesive application was performed as indicated for group B, succeeded by the use of the flowable nanocomposite and light curing for 10 seconds as per the manufacturer’s specification using an LED light curing unit.

Fig. 2: Preparation of specimen for group C – Overcontour preparation done using finishing cylindrical diamond point

Reattached specimens were then subjected to finishing and polishing with the polishing disc immediately after the reattachment to remove any excess composite material if left.

Incubation and Thermocycling

Reattached teeth were then managed in artificial saliva for 48 hours utilizing an incubator stabilized at 37°C, after which the samples were subjected to thermocycling between 5°C and 55°C (±5°C) for 500 cycles with 30 secs dwell time.

Evaluation of Fracture Resistance

A universal testing machine was employed to test the fracture resistance of the reattached specimen, and the intact tooth. The acrylic block with specimen was mounted on the lower plate of the universal testing machine, one at a time, such that the incisal edge was perpendicular to the chisel. Enclosed within the upper plate of the machine was a chisel that facilitated the application of force, achieving contact positioned 2 mm from the incisal edge, as mentioned by Nagi SM and Khadr SM in their study Fig. 3).9

Fig. 3: Fracture resistance evaluation using universal testing machine

Statistical Analysis

The fracture resistance of each reattached fragment was determined using universal testing machine. The load essential for the detachment of each specimen fragment was noted. The values obtained were then subjected to statistical analysis and analyzed using SPSS software V.21.0. One-way ANOVA and post hoc Tukey’s tests were used.

RESULT

Amongst the various groups, the highest mean was observed with Intact teeth (Control group) (372 ± 17.45 N). In the experimental groups, overcontour preparation (295.9 ± 24.00 N) gave the best results, and least was observed with the Chamfer preparation group (170.2 ± 28.39 N), indicating that intact teeth had maximum fracture resistance, followed by reattachment using overcontouring Table 1).

Table 1: Descriptive metrics of fracture load for various tooth preparation methods
Groups N Mean (N) SD
Group A (Control group) 10 372.5 17.450
Group B (Chamfer preparation) 10 170.2 28.397
Group C (Overcontour preparation) 10 295.9 24.002

A statistically significant difference was noted between different preparation techniques, indicating intact teeth (control group) to be the best in terms of fracture resistance of the reattached teeth, and bevel preparation listed the worst results Table 2).

Table 2: Pairwise comparison using post hoc Tukey’s multiple intergroup comparison of fracture load values of tooth reattached using different tooth preparation techniques
Group Comparing group Mean difference (I–J) Std. error Sig. 95% confidence interval
Lower bound Upper bound
Group A (Control group) Group B 202.300* 14.425 0.000 161.311 243.289
Group C 76.600* 14.425 0.000 35.611 117.589
Group B (Chamfer preparation) Group A –202.300* 14.425 0.000 –243.289 –161.311
Group C –125.700* 14.425 0.000 –166.689 –84.711
Group C (Overcontour preparation) Group A –76.600* 14.425 0.000 –117.589 –35.611
Group B 125.700* 14.425 0.000 84.711 166.689
*The mean difference is significant at the p < 0.05 level

DISCUSSION

Dental trauma is prevalent in permanent dentition and may take place at any age, the 1st and 2nd decades of life are when the majority of cases are reported.11,12 Approximately 5% of all physical injuries occur in the oral region.13 A significant 92% of individuals seeking consultation for oral injuries are found to have TDIs. Crown fractures in the maxillary anterior teeth are the most often reported dental injuries, particularly in young children and teenagers.14,15

Reattachment of the tooth fragment is recommended when the fit between the fractured fragment is not hampered, offering several advantages:

Various factors influence the choice of a reattachment technique. Research by Andreassen et al. highlighted dental trauma as the primary cause of fragment loss, leading to a focus on reattachment techniques fracture resistance. Consequently, it is typical to seek out techniques that offer fracture strength comparable to that of intact teeth.16 Hence the purpose of this study was to investigate the influence of different tooth modification techniques, i.e., Chamfer preparation and overcontouring on fracture resistance of tooth fragments reattached utilizing flowable nanocomposite.

A greater percentage of oral injuries affect the front teeth, particularly the maximum incisors, due to their site within the arch structure. Numerous epidemiological studies have revealed that the majority of dental injuries only affect one tooth, with one in six teenagers and one in four adults experiencing a severe oral injury at some point in their lives. Traumatic injuries most commonly affect the upper and lower lateral incisors.17 Hence the permanent maxillary incisors were used in this study.

Careful preparation of bonding surfaces is crucial, as dentinal bonding systems adhere differently to dentin and enamel. To ensure consistent exposed areas, all teeth were uniformly cut 3 mm from the incisal margin, aiming to reduce variations in fracture resistance due to enamel and dentin thickness differences. However, this cutting method differs from natural fractures, by introducing a smear layer and altering surface anatomy. Despite these deviations, cutting was chosen for reproducibility in vitro, though it doesn’t precisely simulate accidental fractures. Using a cutting disc facilitated standardization, minimizing potential biases, thus diamond disc sectioning was employed in our study.4

Nanocomposites offer improved mechanical properties like enhanced fracture toughness, wear resistance, and reduced polymerization shrinkage compared to traditional composites. This is due to nanofillers, which result in higher mean fracture strength, making nanocomposites successful for fragment reattachment. Hence, in our study, we used nanocomposite (3M™ Filtek™ Supreme Flowable Restorative, 3M USPE) for fragment reattachment.1,7

Tooth preparation is extensively researched, with additional techniques being studied. Several authors have discovered that preparing the tooth before reattachment or other procedures can enhance fracture resistance when compared to simple bonding due to adhesion and greater contact area.18 The results of our study revealed the highest fracture strength in group A (control group, Intact teeth) (372 ± 17.45 N) followed by group C (overcontour) (295.9 ± 24.00 N). The least fracture resistance was observed in group B (Chamfer) (170.2 ± 28.39 N).

Group C (overcontouring) (295.9 ± 24.00 N) gave the best fracture resistance values, which can be attributed to the enhanced adhesion area created by the overcontouring of the composite in the vicinity of the fracture site. The wider coverage of the surface allows for a more even distribution of forces over a larger enamel area, resulting in improved performance. However, this increased revelation of the composite resin may lead to persistent esthetic issues resulting from the natural processes of abrasion and discoloration that occur with the passage of time. Fortunately, regular polishing during recall appointments can effectively address this problem.5

Group B (Chamfer) (170.2 ± 28.39 N), the probable cause for the reduced value relative to group A and group C, may stem from the concentration of stresses at the fracture line. The small surface area available for the composite resin application is inadequate to support the fracturing load.19

Thermal cycling is the most common method for simulating the aging of resin-based materials, replicating the thermal stress dental restoratives and natural teeth experience from food and beverage consumption. This technique accelerates aging in a short time. In spite of thorough in vitro investigations, a regulated strategy for the artificial aging of dental materials has yet to be established. Nonetheless, thermocycling is widely recognized as essential for mimicking material aging. Hence, thermocycling was performed in this study.20

The results of our study are in association along with the study conducted by Srilatha et al. and Loguercio et al., which revealed the highest fracture strength recovery values for the overcontour group as compared to those of the internal groove and simple reattachment procedures.5 Similar results appeared in an experimental study performed by Abdulmujeeb et al., which showed that the overcontour and internal groove preparation were superior to Chamfer and simple reattachment procedures.21 According to the study performed by Reis et al., it was found that a basic reattachment lacking additional modification of the fragment or tooth could only restore 37.1% of the sound tooth’s fracture resistance. However, the use of a buccal Chamfer resulted in a recovery of 60.6% of the fracture resistance. Furthermore, preparation with an overcontour and the internal groove restored fracture strengths of 97.2 and 90.5% respectively, which were approximately the same as the findings of this experiment.22,23

The findings of this study indicate that, within its constraints, the reattachment of fractured fragments in the two experimental groups exhibited a statistically significant reduction in fracture resistance compared to the control group, (372 ± 17.45 N) indicating that none of the reattachment techniques was capable of simulating the fracture resistance of reattached teeth to that of intact sound teeth.

Conclusion

None of the reattachment techniques is as successful as the bearing the fracture load with the intact teeth. Thus, rejecting the null hypothesis that reattachment is independent of technique. The analysis revealed that the overcontour technique offered fracture strength similar to that of healthy teeth. It is not advisable to use a Chamfer because the fracture strength attained was low.

Clinical Significance

Understanding the most effective reattachment techniques is essential for dental practitioners to ensure optimal functional and esthetic outcomes for patients with fractured anterior teeth. This study highlights the importance of selecting the appropriate reattachment technique to restore fractured anterior teeth. While no method fully replicates the strength of intact teeth, techniques like overcontouring significantly improve fracture resistance.

ORCID

Ankita Agrawal https://orcid.org/0009-0009-2065-0944

Sandhya K Punia https://orcid.org/0009-0004-1765-8412

Yogender Kumar https://orcid.org/0009-0002-4699-3792

Shilpi Kushwaha https://orcid.org/0009-0002-9034-7261

REFERENCES

1. Chandran R, Rayar S, Ravi AB, et al. Comparative evaluation of fracture resistance of incisor fragments using simple, bevel, internal groove preparation designs and reattached with nanocomposites: An in vitro study. J Pharm Bioallied Sci 2020;12(Suppl 1):S373–S377. DOI: 10.4103/jpbs.JPBS_110_20.

2. Kulkarni VK, Gadhe DE, Gavade SS, et al. Finite element analysis for fracture resistance of reattached human tooth fragment with different types of retentive preparation techniques. J Clin Pediatr Dent 2022;46(5):81–87. DOI: 10.22514/jocpd.2022.011.

3. Güngör HC. Management of crown‐related fractures in children: An update review. Dent Traumatol 2014;30(2):88–99. DOI: 10.1111/edt.12079.

4. Stellini E, Stomaci D, Stomaci M, et al. Fracture strength of tooth fragment reattachments with postpone bevel and over contour reconstruction. Dent Traumatol 2008;24(3):283–288. DOI: 10.1111/j.1600-9657.2007.00539.x.

5. Srilatha JS, Chhasatia N, Rani PJ, et al. Reattachment of fractured anterior teeth-determining fracture strength using different techniques: An in vitro study. J Contemp Dent Pract 2012;13(1):61–65. DOI: 10.5005/jp-journals-10024-1096.

6. Kaur Atwal PK, Singh R. A combined approach to restore a fractured tooth: Reattachment and composite veneering. Guident 2016;9(6):52–55.

7. Bommanagoudar J, Chandrashekhar S, Sharma S, et al. Comparison of enamel preparations-bevel, chamfer and stair step chamfer on fracture resistance of nano filled resin composites using bulk pack technique–An in vitro study. Open Access Maced J Med Sci 2019;7(23):4089–4093. DOI: 10.3889/oamjms.2019.853.

8. Coelho-de-Souza FH, Rocha AD, Rubini A, et al. Influence of adhesive system and bevel preparation on fracture strength of teeth restored with composite resin. Braz Dent J 2010;21(4):327–331. DOI: 10.1590/s0103-64402010000400007.

9. Nagi SM, Khadr SM. Influence of different tooth preparation and bonding techniques on the fracture resistance of tooth fragment reattachment. Biomater Investig Dent 2021;8(1):112–118. DOI: 10.1080/26415275.2021.1952873.

10. Poubel DL, Almeida JC, Dias Ribeiro AP, et al. Effect of dehydration and rehydration intervals on fracture resistance of reattached tooth fragments using a multimode adhesive. Dent Traumatol 2017;33(6):451–457. DOI: 10.1111/edt.12344.

11. Bücher K, Neumann C, Hickel R, et al. Traumatic dental injuries at a German university clinic 2004-2008. Dent Traumatol 2013;29(2):127–133. DOI: 10.1111/j.1600-9657.2012.01149.x.

12. Andreasen JO. Etiology and pathogenesis of traumatic dental injuries A clinical study of 1,298 cases. Scand J Dent Res 1970;78(1‐4):329–342. DOI: 10.1111/j.1600-0722.1970.tb02080.x.

13. Eilert-Petersson E, Andersson L, Sorensen S. Traumatic oral vs. non-oral injuries. An epidemiological study during one year in a Swedish county. Swed Dent J 1997;21(1–2):55–68. PMID: 9178450.

14. Andreasen JQ, Ravn JJ. Epidemiology of traumatic dental injuries to primary and permanent teeth in a Danish population sample. Int J Oral Surg 1972;1(5):235–239. DOI: 10.1016/s0300-9785(72)80042-5.

15. Andreasen JO. Textbook and color atlas of traumatic injuries to the teeth. Munksgard: Copenhagen; 1993. pp. 155–173.

16. Reis A, Loguercio AD, Kraul A, et al. Reattachment of fractured teeth: A review of literature regarding techniques and materials. Oper Dent 2004;29(2):226–233. PMID: 15088736.

17. Maitin N, Maitin SN, Rastogi K, et al. Fracture tooth fragment reattachment. BMJ Case Rep 2013;2013:bcr2013009183. DOI: 10.1136/bcr-2013-009183.

18. Garcia FC, Poubel DL, Almeida JC, et al. Tooth fragment reattachment techniques—A systematic review. Dent Traumatol 2018;34(3):135–143. DOI: 10.1111/edt.12392.

19. VamsiKrishna R, Madhusudhana K, Swaroopkumarreddy A, et al. Shear bond strength evaluation of adhesive and tooth preparation combinations used in reattachment of fractured teeth: An ex-vivo study. J Indian Soc Pedod Prev Dent 2015;33(1):40–43. DOI: 10.4103/0970-4388.148975.

20. Eliasson ST, Dahl JE. Effect of thermal cycling on temperature changes and bond strength in different test specimens. Biomater Investig Dent 2020;7(1):16–24. DOI: 10.1080/26415275.2019.1709470.

21. Abdulkhayum A, Munjal S, Babaji P, et al. In-vitro evaluation of fracture strength recovery of reattached anterior fractured tooth fragment using different re-attachment techniques. J Clin Diagn Res 2014;8(3):208–211. DOI: 10.7860/JCDR/2014/7161.4164.

22. Reis A, Francci C, Loguercio AD, et al. Re-attachment of anterior fractured teeth: Fracture strength using different techniques. Oper Dent 2001;26(3):287–294. PMID: 11357572.

23. Loguercio AD, Mengarda J, Amaral R, et al. Effect of fractured or sectioned fragments on the fracture strength of different reattachment techniques. Oper Dent 2004;29(3):295–300. PMID: 15195730.

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