Comparison of three protocols for the management of re‐fracture of teeth with uncomplicated crown fractures

Abstract

Background: Crown fractures restored by fragment reattachment are liable to refracture, which may cause fragment dislodgement. There is a paucity of literature regarding management of fragment reattachment cases following a further fracture.Hence the aim of the present in-vitro study was to evaluate and compare the efficacy of three different management protocols for such scenarios.Methodology: Eighty maxillary bovine incisors without structural deformity and with similar dimensions were fractured as per the standard protocol. They were subjected to drying for 24 hours and the fragments were rehydrated by placing them in a humidification chamber for 15 minutes. They were then reattached by using flowable light-cured composite resin. The teeth (n=20) were fractured again by fixing them in a mechanical frame and using a mallet. They were randomly allocated to three experimental groups. (Group I mechanical abrasion and fragment reattachment, Group II mechanical abrasion, humidification and reattachment, Group III mechanical abrasion and composite restoration, and Group IV positive control with no re-fracture). The samples were thermocycled and the force required to fracture was tested by using a universal testing machine (Instron-3360, USA). This was done by applying a tangential load with a speed of 1 mm/min to the teeth with a 500-kg load cell. Statistical analysis of the results was performed using ANOVA and the independent t-test. Results:The highest force required to fracture was reported in Group IV (333.26 ± 66.69N) while the lowest was in Group II (254.86 ± 105.23N). The forces in Group I and Group II were 258.36 ± 65. 78N and 298.02 ± 97.94N, respectively (p=0.016, F=3.68). The independent t-test between the groups revealed a significant difference between Group I and Group IV (p= 0.001) and Group II and Group IV (p=0.009). Conclusion:The force required to fracture was significantly lower in the groups involving attachment of the re-fractured fragments. Among the experimental groups, the group with composite restoration required the highest force to fracture.

Comparative evaluation of fragment reattachment protocols for the management of teeth with crown‐root fractures

“…Teeth which were free of structural deformities were selected. 6,7 A thorough cleaning of tissue remnants was performed by means of an ultrasonic scaler, and the teeth were stored in artificial saliva until the day of the experiment. 6,7 The teeth were randomized into four groups: Group I-Control Group (sound teeth); Group II-dehydrated for 24 h; Group IIIrehydrated in distilled water for 15 min and Group IV-rehydrated in a humidification chamber for 15 min (Table 1).…”

“…6,7 A thorough cleaning of tissue remnants was performed by means of an ultrasonic scaler, and the teeth were stored in artificial saliva until the day of the experiment. 6,7 The teeth were randomized into four groups: Group I-Control Group (sound teeth); Group II-dehydrated for 24 h; Group IIIrehydrated in distilled water for 15 min and Group IV-rehydrated in a humidification chamber for 15 min (Table 1). A crown-root fracture extending from the labial side of the middle one-third of the crown to the palatal side of the cervical-third of the root was created for each experimental tooth.…”

“…This was done by utilising the method described in previous studies. 6,7 Briefly, a line was marked by using an indelible pencil covering the regions mentioned above. A groove of 1 mm depth was created using a diamond disc and a force perpendicular to the fracture line labio-lingually was manually applied using a dental mallet to simulate a crown-root fracture (Figure 1A,B).…”

“…A groove of 1 mm depth was created using a diamond disc and a force perpendicular to the fracture line labio-lingually was manually applied using a dental mallet to simulate a crown-root fracture (Figure 1A,B). 6,7 This resulted in fragments and the crown-root stumps (CRS) which were coded, so that the same pair could be used for further reattachment experiments. The stumps of the Groups II, III, and IV and the intact teeth of Group I were stored in artificial saliva again, while the fragments were exposed to the environment under normal temperature and pressure (Table 1).…”

“…The fragments in Group III were rehydrated by immersing them in distilled water in a plastic container for 15 min, while those in Group IV were rehydrated in a humidification chamber for 15 min as per the protocol described in previous studies. 6,7 Briefly, the humidification chamber was operated for 20 min to create a humidity level of 80%-85% at normal temperature and pressure. The tooth fragments were placed in the upper chamber on an acrylic plate at a distance of 5 cm from the humidifier vent.…”