Enamel-dentin crown fractures bonded with various bonding agents

Influence of different tooth preparation and bonding techniques on the fracture resistance of tooth fragment reattachment

Purpose

comparing the influence of different tooth preparation and bonding techniques on the fracture resistance of tooth fragment reattachment.

Materials and method

Ninety bovine central incisors were selected. Fifteen teeth act as a control (Group A). Experimental specimens were sectioned at the mesial-incisal proximal edge 3 mm from the incisal edge in a labio-lingual direction at 25degree inclination apically. Experimental specimens were then divided into five groups according to the tooth reattachment techniques utilized; Group B: no tooth preparation + Cured bond + Flowable composite; Group C: no tooth preparation + Uncured bond + Flowable composite; Group D: Bevel + bond + Flowable composite; Group E: Over-contouring + bond + Nanohybrid composite; Group F: Over-contouring + bond + Flowable composite. Specimens were subjected to thermocycling between 5 °C and 55 °C for 500 cycles with 30 sec. dwell time. Fracture strength was evaluated using universal testing machine. Data was analyzed using One-way ANOVA.

Results

There was a statistically significant difference between Group A and all the experimental groups, p < .001. Group E showed the highest statistically significant fracture resistance mean value compared to other experimental groups, while the lowest mean value was found in Group B.

Conclusion

Though, none of the tested techniques resulted in fracture resistance similar to that of intact teeth, over-contouring technique with nanohybrid composite application showed better performances compared to the other techniques tested in the current study. Bonding plus flowable resin composite application with no additional tooth preparation and placement of a bevel are not suggested due to the low fracture strength achieved.

Comparative Evaluation of the Fracture Resistance of Two Different Fiber-reinforced Composite Restorations with Particulate Filler Composite Restorations

Uncomplicated crown fractures are the most common form of traumatic dental injuries (TDIs) in children affecting their personal and social well-being.

The Coronal Tooth Fractures: Preliminary Evaluation of a Three-Year Follow-Up of the Anterior Teeth Direct Fragment Reattachment Technique Without Additional Preparation

Objective:

The aim of this research is to describe and to analyse the long-term results and the clinical steps of direct fragment reattachment technique with no additional tooth preparation, used to treat crown fracture. This technique achieves the clinical success, combining satisfactory aesthetic and functional results with a minimally invasive approach.

Methods:

The 3 years follow-up included 9 patients (5 males, 4 females) with coronal fracture. In all the cases the fragment was available and intact. The authors illustrate the adhesive procedure used. Under local anaesthesia and after positioning the rubber dam, both the tooth and the fragment surface were etched, rinsed and applied by the adhesive system in order to obtain the retention of the fractured part to the tooth without additional tooth preparation or resin cement.

Results:

The statistical analysis shows the good performances of direct fragment reattachment technique. After 36 months, in 22.2% of the cases, the detachment was observed of the bonded fragment and in 11.1% of patients, complications were recorded.

Conclusion:

Our clinical experience shows how the ultra-conservative procedure used is fast, easy and offers a long term predictability; it also allows good functional and aesthetic outcomes.

Influence of Root Canal Posts on the Reattachment of Fragments to Endodontically Treated Fractured Incisors: An in vitro Experimental Comparison

OBJECTIVE

The aim of this study was to establish the benefits of inserting a fiberglass post when bonding tooth fragments after complicated coronal fractures.

METHODS

Thirty bovine incisors were randomly assigned to three groups: a control group of intact teeth (A), and two experimental groups (B and C). Coronal fragments were cut from the teeth in groups B and C, which then underwent root canal treatment, inserting posts in the teeth in group C. The coronal fragments were bonded to the teeth in both experimental groups using the same materials and technique, then the specimens were submitted to mechanical loading until fracture.

RESULTS

The specimens in the experimental groups had a lower resistance to mechanical loading than the intact teeth. The mean failure load was: 352.77 (SD ± 62.22) N in group A, 151.04 (SD ± 45.76) N in group B, and 168.61 (SD ± 33.59) N in group C. The difference between group A and the other two groups was statistically significant (analysis of variance test: p < 0.0001), whereas there was no statistically significant difference in the force needed to fracture the teeth in groups B and C (Tukey's test: p = 0.34). When the failure mode under loading was examined, the fractures in group C never involved new tooth substance beneath the adhesion interface, whereas in group B, this was only true in one in two cases.

CONCLUSIONS

Inserting a post does not significantly improve the strength of restored teeth, but it may result in a more favorable fracture mode.

CLINICAL SIGNIFICANCE

Within the limitations of this in vitro study, reattaching the fragment of a fractured tooth does not seem to restore the tooth to its original load resistance. The findings of this study indicate that inserting a fiberglass post for reinforcement purposes in fractured teeth undergoing root canal treatment is unable to significantly improve their load-bearing capacity by comparison with teeth repaired without inserting a post. However, the results of the present study suggest that inserting a post may result in a more favorable fracture mode in the event of further trauma.

In vitro fracture resistance of mandibular incisors restored with modified partial-coverage ceramic restorations

BACKGROUND/AIM

The aim of this in vitro study was to investigate the impact fracture resistance of anterior teeth that had been fractured and restored with modified partial-coverage ceramics using the edge-up technique.

MATERIAL AND METHODS

A total of 178 extracted human mandibular central and lateral incisors were included in this study. The incisors were randomly divided into two groups. Group 1 (n = 89) teeth were cleaved and restored with modified partial-coverage ceramics using the edge-up technique; Group 2 (n = 89) consisted of intact teeth that served as control. Impact strength was tested in a modified impact testing machine (pendulum type), and the severity of crown fracture after fracture resistance test was registered.

RESULTS

Impact strength was insignificantly lower in restored teeth (median 5.39 and range 0.81-14.12 kJ m(-2) ) than in intact teeth (median 5.45 and range 0.31-16.47 kJ m(-2) ), although no statistically significant differences were observed. Regarding the severity of crown fracture, restored teeth showed a lower rate of severe fractures (20.22%) compared to intact teeth (25.84%), but no statistically significant differences were observed.

CONCLUSIONS

Restoration of cleaved mandibular incisors with modified partial-coverage ceramics using the edge-up technique shows fracture resistance and severity of crown fracture following traumatism similar to intact teeth. In this way, this technique can be used successfully for the treatment of fractured anterior teeth.

Tooth fragment reattachment technique on a pluri traumatized tooth

This case report describes and analyses a tooth fragment reattachment technique used to resolve crown fractures of the anterior teeth. This treatment allows a conservative approach to traumatic coronal lesions offering a better possibility of maintaining aesthetics and function. The authors have illustrated here a clinical case of a fractured incisor. This case is characterized by several traumas on the same tooth that required different therapeutic solutions. We used an easy and ultra-conservative technique without any tooth preparation in the first and third traumatic injuries. In the second trauma, a direct restoration of the fractured tooth was performed. The adhesive reattachment is a simple system to achieve good aesthetic and functional results.Our clinical experiences demonstrated that, when tooth and fragment margins are intact, the reattachment technique without any tooth preparation is a simple and predictable procedure. Quality of adhesion is shown by the retention of the reattached fragment in the second trauma that caused only partial enamel fractures.

Hydration and Dehydration Periods of Crown Fragments Prior to Reattachment

Introduction

Tooth fragment bonding is an excellent treatment option in dealing with traumatic injuries of the anterior teeth. Rewetting the tooth fragment has been shown to increase restoration durability. The present study examined the effect various dry and wet storage periods had on the reattached fragment's bond to the tooth.

Materials and Methods

One hundred and eight human mandibular incisors were fractured and assigned to undergo a dehydration period of 30 minutes, six hours, 24 hours, or three days before the rewetting procedure. After fracturing the teeth and drying the fragments, each of the specimens was assigned to one of the three main groups (A, B, or C) intended to evaluate the effect of different rehydration periods. Groups A and B underwent a 30-minute and a 24-hour rewetting period, respectively. Group C served as a control (without a rewetting stage). Tooth fragments were then reattached and prepared for the strength test. Force was applied on the lingual side of the tooth at a 1 mm/min rate until failure.

Results

The mean loads (N) required to fracture the restored teeth were as follows: 204.43 ± 33.48 N, 322.59 ± 34.62 N, and 253.25 ± 29.05 N for groups A, B, and C, respectively. Two-way analysis of variance (p&lt;0.05) showed that rehydration and dehydration periods as well as their interaction caused significant differences in the strength of the final restoration. Multiple comparison tests showed that, in general, significant differences were not seen among different dehydration times prior to the rewetting stage (p&gt;0.05), except in the case of the 30-minute dehydrated specimens (p&lt;0.05).

Conclusion

Compared to a 30-minute period, a 24-hour rehydration of the tooth fragment before treatment seems to salvage enough moisture to result in an increase in reattachment strength.

A biological approach to crown fracture: Fracture reattachment: A report of two cases

The development of adhesive dentistry has allowed dentists to use the patient's own fragment to restore the fractured tooth, which is considered to be the most conservative method of treatment of crown fracture allowing restoration of original dental anatomy, thus rehabilitating function and esthetics in a short time by preserving dental tissues. The tooth fragment reattachment is preferred over full coverage crowns or composite resin restoration because it conserves sound tooth structure, and is more esthetic, maintaining the original anatomy and translucency, and the rate of incisal wear also matches that of original tooth structure. Presented here is a report of two cases of crown fracture managed by reattachment procedures.

Shear bond strength of restorations applied to un-complicated crown fractures: an in vitro study

BACKGROUND

Study was designed to evaluate shear bond strengths of different restorative techniques of uncomplicated enamel-dentin fractures in permanent incisors.

MATERIAL AND METHODS

Forty human mandibular incisors were divided into four groups. One-third of their anatomical crowns from the incisal edges were cut off in three groups, representing an uncomplicated enamel-dentin fracture. Intact teeth in group 1 were used as control. In group 2, edge fragments were reattached by flowable composite (Filltek Flowable Supreme XT). In group 3, teeth were restored with universal resin composite (Filtek Z 250). In group 4, pre-impregnated glass fiber sheet (everStickNet) was positioned onto fractured surface, and then restorations were completed with resin composite. Three-step etch-and-rinse adhesive system (Adper Scotchbond Multi Purpose) was used in all test groups. Shear bond strengths of all samples were determined in universal testing machine, and data were analyzed with Kruskal-Wallis followed by Mann-Whitney U tests. Failure types were observed by light microscope.

RESULTS

Shear bond strength of sound teeth was significantly higher than those of restored teeth (P < 0.05). Mean shear bond strengths of the reattached teeth were lower than the other two restoration types; however, differences were not statistically significant (P > 0.05).

CONCLUSIONS

Load-bearing capacity of restored teeth was not as high as sound teeth in the uncomplicated crown fracture. However, shear bond strength of different types of restorations seems close to each other.

A single visit, reattachment of fractured crown fragment

“Minimal intervention with maximum dentistry” The immediate restorative technique resolving the acute problem of traumatic tooth fracture with pulpal involvement–An immediate fracture fragment reattachment using pre-fabricated fiber post with dual cure cement–A challenging, conservative, aesthetics, rehabilitating, functionally, and economically viable single visit procedure.

Reattachment of rehydrated dental fragment using two techniques

The reattachment of dental fragments is a conservative treatment and should be considered in the restoration of anterior tooth fractures. This study compared the fracture strength of dehydrated and rehydrated tooth fragments submitted to two different bonding techniques.

MATERIALS AND METHODS

Sixty human central and lateral mandibular incisors were divided into six groups and sectioned 3 mm from the incisal edge, using a diamond disk. Two reattachment techniques were applied: (a) bonding, using the Single Bond adhesive system and FiltekZ250 composite resin, followed by placement of a chamfer on the fracture line that was filled with composite resin (Groups 1, 3 and 5); and (b) use of the same bonding technique after dentin removal from the tooth fragment (Groups 2, 4 and 6). The following hydration treatments were applied to the fragments before bonding: (a) 48-h hydration (Groups 1 and 2); (b) 48-h dehydration (Groups 3 and 4); (c) 48-h dehydration followed by rehydration 30 min before bonding (Groups 5 and 6). The reattached teeth were mounted in acrylic resin cylinders and stored in distilled water for 24 h. The specimens were fractured at a speed of 1 mm min(-1) in a universal testing machine.

RESULTS

The following mean fracture strengths (kgf) were recorded: (G1) 12.9 +/- 0.6; (G2) 18.8 +/- 4.8; (G3) 7.3 +/- 1.5; (G4) 15.2 +/- 2.4; (G5) 13.4 +/- 2.2; and (G6) 17.1 +/- 3.2. Analyses using two-way anova and the Tukey test (P < 0.01) revealed significant differences between the restorative techniques and the hydration treatments.

CONCLUSIONS

The bonding technique that incorporated dentin removal from the fragment before bonding showed greater fracture strength across all groups. Fragment dehydration for 48 h caused a reduction in fracture strength, which was recovered by a 30-min rehydration.

Fracture strength of tooth fragment reattachments with postpone bevel and overcontour reconstruction

The purpose of this study was to test the actual resistance against fracture of a crown fragment fractured and reattached using three different techniques of preparation. Forty bovine incisors were randomly assigned into four groups of which the first was the control group. The elements of the three experimental groups were all cut at a fixed distance of 3 mm for the incisal margin on the buccal surface of the crown in a plane normal to the buccal surface itself, and subsequently re-bonded using an adhesive system. After the reattachment, on the teeth of group 2, a circumferential chamfer was performed along the fracture line; on the teeth of group 3 a groove called 'overcontour' was made also along the fracture line; the teeth in group 4 received a chamfer on the buccal surface and an overcontour on the lingual surface. Finally, all the elements were encompassed in chalk blocks and the models were mounted on the 858 Mini Bionix to perform a fatigue load test. A force was applied on the buccal surface of each tooth at 1.5 mm from the incisor margin, with a velocity of 1 mm min(-1), through the use of a steel prick. All the elements of groups 2, 3 and 4 demonstrated a lower resistance to fracture in comparison with the elements of the control group. The teeth of group 2 showed a resistance to fracture equal to 36.1% of the resistance of the elements in the control group; in group 3 the resistance was equal to 50.2%, while in group 4 the resistance reached 55.9%. The difference in resistance between group 3 and group 4 did not result statistically significant (P = 0.82). Reattachment of coronal fragments does not restore the resistance to fracture to an equal level of the intact teeth, in a static test. The different techniques of preparation significantly modify the resistance to the fracture of a re-bonded fragment. The technique of the circumferential chamfer produced results that were less favourable in terms of resistance against fracture.

Re-attachment of a fractured tooth: a case report

A 16-year-old patient who fractured her maxillary central incisors is presented. One of the original tooth fragments was available. The fracture was clean and there was no pulpal exposure. Juxtaposition of the fragment to the tooth showed that the margins of each fitted well against each other and no interfragmentary space was present. The fragment was re-attached with an adhesive bonding agent and the other tooth was restored with a resin composite. The esthetic result achieved in a single appointment was excellent. The tooth was vital and there was no change in the color of the tooth in 1-year recall.

Reattachment of a fractured permanent molar cusp: a 12-month follow-up

A posterior crown fracture due to acute trauma is an uncommon type of dental injury. This case report presents combined endodontic-bioadhesive treatment of a complicated crown fracture of a permanent molar due to a horse riding accident. Endodontic therapy was initiated following surgical removal of the fractured mesiolingual cusp, which was stored frozen until bonding procedures could be carried out. Subgingival and proximal contours of the missing cusp were maintained by an interim glass-ionomer restoration during endodontic therapy. Following root-canal obturation, the fractured cusp was reattached using a total-etch adhesive and composite resin system. The patient was recalled at 1, 3, 6 and 12 months, demonstrating excellent clinical and radiographic findings.

Fracture resistance of re-attached coronal fragments--influence of different adhesive materials and bevel preparation

The purpose of this study was to investigate the fracture resistance of re-attached coronal fragments of teeth using different materials and tooth preparations. Seventy-two recently extracted bovine incisors were selected. Eight incisors were maintained without any preparation as a control group. The incisal third of the other teeth was sectioned using a diamond saw. In one group (n = 32), a 2-mm bevel was prepared, whereas in the second group no preparation was made (n = 32). The specimens (beveled and non-beveled) were divided in four groups (n = 8) and re-attached with the following materials: a dual-cured resin cement RelyX ARC (RX); a chemically cured composite Bisfil 2B (B2); a light-cured composite Z250 (Z2); and a one-bottle adhesive Single Bond (SB). The bevel region was restored with adhesive and composite. All materials were used according to manufacturer's directions. A light-curing unit was used to polymerize the materials. Specimens were stored in saline solution for 72 h. De-bonding procedures were performed in a testing machine with cross-head speed of 0.6 mm min(-1). The load was applied in the incisal third. The resistance to fracture for control group was 70 (7) kg. The fracture resistance for non-beveled and beveled specimens were: SB, 3.3 (2.4) and 17.0 (4.1); RX, 11.5 (3.0) and 16.3 (3.1); Z2, 14.4 (4.2) and 20.5 (1.7); and B2, 19.5 (3.5) and 32.5 (7.4) kg. Analysis of variance (anova) and Fisher's protected least significant difference (PLSD) test disclosed significant influence for materials and cavity designs (P = 0.001). The highest failure loads were obtained with the B2 group and then with the Z2 with either bevel or non-bevel. RX produced lower failure loads than the restorative composites. The lowest failure load was obtained with SB in the non-beveled group. No technique studied was able to attain the fracture resistance of the control group and both materials and tooth preparation influenced the fracture resistance.

Effects of surface treatment and joint shape on microtensile bond strength of reattached root dentin segments

STATEMENT OF PROBLEM

An effective bonding technique for reattaching vertical root fracture segments has not yet been established.

PURPOSE

The purpose of this study was to investigate the effects of surface treatment and joint shape on bond strength of reattached root dentin segments.

MATERIAL AND METHODS

Microtensile dentin specimens (n=120, cross-sectional area=1.5 mm2) were obtained from 12 bovine teeth roots, and fractured under a tensile force. The segments of each group (n=6) were reattached by a 4-META/MMA-TBB adhesive resin after different treatments (etching or polishing, a 50-microm or 500-microm gap space, butt or wedge joint). The group with a 50-microm gap space and butt joint, which was not etched or polished, served as the control. After 24 hours of storage in 0.9% normal saline solution or thermal cycling (3000 cycles, 4 degrees C and 60 degrees C), the specimens were fractured in a universal testing machine at a crosshead speed of 1.0 mm/min. The microtensile bond strengths (MPa) were recorded. The bonded interface and fractured surface were observed by SEM (original magnification x 1000). The results were analyzed by a 2-way analysis of variance and the Fisher protected least significant difference post-hoc test (alpha=.05).

RESULTS

Significantly higher bond strengths (P=.0001) were shown for the nonpolished group (9.78 +/- 4.44 MPa) and the etched group (9.31 +/- 1.23 MPa) than for the polished group (fractured before test). The wedge-shaped joint exhibited the highest bond strength (18.57 +/- 3.40 MPa, P=.0017). SEM observations showed that the penetration of resin tags along the oblique dentinal tubules was within the wedge joint.

CONCLUSION

Etching and oblique tubule orientation contributed to significantly high bond strength of reattached segments to dentin after vertical root fracture.

Shear bond strengths of tooth fragments reattached or restored

This study investigated the shear bond strengths of sectioned human mandibular incisor edge fragments reattached using luting cements, bonding agents or restored with composite resins. Seventy teeth were randomly distributed among six experimental groups and a control group. Leaving half of the anatomic crowns exposed, the teeth were embedded in self-cure acrylic resins with the exposed part then sectioned. The fragments in groups 1-4 were bonded to their respective teeth using Clearfil Liner Bond 2V, Scotch Bond Multi Purpose Plus, Panavia-F and 3M Opal Luting cement. The 5th and 6th groups were restored with composite resins (Silux 3M and Clearfil AP-X) using their bonding agents (Single Bond and Clearfil SE Bond). The results indicated that reattachment of fractured incisal fragments by using new generation bonding agents was effective against shear stresses, comparable with the intact teeth. Instead of restoration with composite resins therefore reattachment of a fractured fragment might be more preferable in cases of dental trauma.

Long-term calcium hydroxide as a root canal dressing may increase risk of root fracture

It has been proposed (Cvek 1992) that immature teeth are weakened by filling of the root canals with calcium hydroxide dressing and gutta-percha. The aim of the present study was to test the hypothesis that dentin in contact with calcium hydroxide would show a reduction in fracture strength after a certain period of time. Immature mandibular incisors from sheep were extracted and divided into two experimental groups. Group 1: the pulps were extirpated via the apical foramen. The root canals were then filled with calcium hydroxide (Calasept) and sealed with IRM(R) cement, and the teeth were then stored in saline at room temperature for 0.5, 1, 2, 3, 6, 9, or 12 months. Group 2: the pulps were extirpated and the root canals were filled with saline and sealed with IRM(R) cement. The teeth were then stored in saline for 2 months. Intact teeth served as controls and were tested immediately after extraction. All teeth were tested for fracture strength in an Instron testing machine at the indicated observation periods. The results showed a markedly decrease in fracture strength with increasing storage time for group 1 (calcium hydroxide dressing). The results indicate that the fracture strength of calcium hydroxide-filled immature teeth will be halved in about a year due to the root filling. The finding may explain the frequent reported fractures of immature teeth filled with calcium hydroxide for extended periods.

Fractured teeth bonded with dentin adhesives with and without unfilled resin

Fractured incisors were restored by reattaching the fragment to the remaining tooth structure. For this purpose, seven dentin adhesive systems were used with and without an unfilled resin (Heliobond) and the strength of the restored teeth was tested at a cross-head speed of either 1 or 500 mm/min. The hypothesis was that the strength of the reattachment would be higher when an unfilled resin was used. The dentin adhesive systems were Prime & Bond NT (PB), Excite (EX), One-Step (OS), PQ1 (PQ), SingleBond (SB), Optibond Solo Plus (OS), and an experimental adhesive (GL). Statistical analysis revealed that with all adhesives except EX, a significantly greater mean fracture strength was achieved when the adhesives were used with the resin (Heliobond). Furthermore, with all adhesives except PB, there was a significantly lower mean fracture strength when tested at 500 mm/min than at 1 mm/min. All the tested adhesives except EX should be used with an unfilled resin when restoring fractured teeth by reattachment.

Mechanical strength of tooth fragment reattachment

The aim of this study was static and fatigue test investigation of the strength of a tooth fragment reattached with adhesives to the tooth body. Central bovine incisor teeth were used, and standardized fragments were obtained by cutting the incisal edge of the selected teeth. All the fragments were reattached using a multistep dentine adhesive system, and the specimens were randomly divided into two groups (A and B). Group B specimens underwent a further dental treatment: a circumferential double chamfer prepared around the external cut interface was filled with light cured composite restorative resin. Static and fatigue bending tests were performed and linear elastic equations were used to analyze and compare the strength of the treated teeth. The results indicated that the static and fatigue bending properties were improved by using reinforcement with composite restorative resin.

Incisal edge reattachment: indications for use and clinical technique

This article presents an overview of the evolution of the incisal edge reattachment procedure. Case reports are described of patients presenting with traumatised teeth in which the reattachment procedure was performed. A review is provided of present in vivo studies detailing long-term success rates in the clinical application of this procedure. Finally, a recommended technique for diagnosis and treatment is offered to improve success in this procedure which may benefit a significant segment of the paediatric and adolescent populations.

Rationalization of esthetic restorative dentistry based on biomimetics

The exponential progressivism that characterizes the current decade often comes with substantial financial implications. Dental care is not spared by this phenomenon. However, new generations of concepts emerging from biomimetics provide the operator with the ability to restore the biomechanical, structural, and esthetic integrity of teeth. The development of adhesion and the evolution of porcelain veneers constitute striking examples of this nascent process. Indications for bonding porcelain are extending to more perilous situations (crown-fractured incisors, nonvital teeth), resulting in considerable improvements, comprising both the medical-biologic aspect (economy of sound tissues and maintenance of tooth vitality) and the socioeconomical context (decrease of costs compared to traditional and more invasive prosthetic treatments).

CLINICAL SIGNIFICANCE

In the bonded porcelain veneer and its extensions, restorative dentistry has found new solutions for the anterior segment that balance the need for functional and esthetic reconstruction. The optimal stiffness of porcelain in thin section, the ideal surface characteristics, and the biomechanical continuum achieved through high performance bonding mean the crown of the tooth as a whole can support incisal or masticatory function. By the same token, the conduction of optical effects from within the tooth combined with the ideal surface features of the porcelain veneer make this restorative approach the ultimate in esthetic satisfaction, for both the practitioner and the patient.

Pulp reactions to restoration of experimentally induced crown fractures

OBJECTIVES

Reattachment of the avulsed enamel-dentine coronal fragment to the remaining tooth structure has become an accepted clinical alternative to a resin composite build-up for the restoration of crown fractured teeth. Since little knowledge exists as to the pulpal response to this procedure, this study was designed to observe the condition of the pulp following experimentally induced crown fracture and restoration in monkeys.

METHODS

Experiments were conducted in eight young green Vervet monkeys (Cercopithecus aethiops). In all, 64 fractured incisors were investigated. Light microscopic examination of pulp tissue specimens was carried out after 3 months of observation.

RESULTS

The evaluation was restricted to specimens having a fracture plane within 2 mm of the pulp and no pulpal exposure. In general, pulp tissue was well preserved irrespective of the restorative procedure. Even if the restoration or the bonded tooth fragment had been lost during the follow-up period, the pulp generally remained in good condition. Inflammatory infiltrates where seen in only a few specimens and then as clusters of mononuclear leukocytes. Hard tissue repair was frequently observed and displayed various configurations from isolated hard tissue deposits to areas of extensive hard tissue repair in the coronal portion of the pulp. Pronounced hard tissue repair and occurrence of inflammatory cell infiltrates correlated with the presence of stainable bacteria on the fractured dentine surface.

CONCLUSIONS

In the absence of direct exposure, reparative dentine is a frequent feature of the pulp's response to crown fracture and restoration with composite or reattachment of the crown fragment with dentine bonding. These restorative procedures appear to ensure continued function of the underlying pulp.

Adhesive bonding of fragmented anterior teeth

This in vitro study investigated the fracture strengths of fractured incisors after reattachment to the remaining tooth structure, using either Gluma dentin-bonding agent together with 1 of 13 different experimental resins or 1 of the following dentin-bonding agents: Gluma+ (experimental modification of Gluma), Panavia21, ScotchBond1 (SingleBond), All-Bond2, Dentastic, SuperBond, Prime&Bond 2.1. No significant differences were found in the experiments with various experimental resins. The fracture strength of teeth rebonded with Gluma, All-Bond2, Dentastic, SuperBond or Prime&Bond 2.1 showed mean fracture strengths in the range of 8.7-11.2 MPa, which were significantly different in all cases from that of intact teeth (16.3 MPa). Teeth bonded with Gluma+, Panavia21 or ScotchBond1 (SingleBond) showed mean fracture strengths of 15.5, 14.6, and 14.2 MPa, respectively. These fracture strengths were not significantly different from that of intact teeth.

An in vitro investigation into the shear bond strengths of two dentine-bonding agents used in the reattachment of incisal edge fragments

This in vitro study investigated the shear bond strengths of sectioned bovine incisal edge fragments reattached using Gluma 2000 and Scotchbond 2. Teeth were sectioned 3 mm from the incisal edge using an Acutome with a 0.5 mm diamond wheel running at 90 degrees to the mesial or distal surface of the tooth. Twenty four incisal fragments were rebonded with each of the dentine bonding agents; a further 24 intact incisors were used as a control group. The control group required a mean fracture force of 940(+/- 144) N which was significantly greater (p < 0.01) than that required to fracture fragments rebonded using GLUMA 2000 (609 +/- 116) N and Scotchbond 2 (393 +/- 97) N. The mean force required to fracture incisal fragments rebonded with GLUMA 2000 was significantly greater (p < 0.01) than that required to fracture incisal fragments rebonded with Scotchbond 2.

Resistance to vertical fracture of roots, previously fractured and bonded with glass ionomer cement, composite resin and cyanoacrylate cement

A recently developed glass ionomer bone cement (Ionos) may be suitable for bonding vertically fractured teeth, but the resulting resistance to repeated fracture of the bonded teeth is unknown. The purpose of this study was to assess in vitro the resistance to repeated fracture of roots which were previously fractured and bonded with Ionos cement and other bonding agents. Thirty-six roots were separated at the cervix and grooved on the coronal surface. Each root was mounted in an Instron machine and a vertical force was exerted until fracture occurred. Both the force required to fracture the root (F) and the root surface area (A) were recorded, and the root halves were bonded with one of the following materials: Ionos bone cement without dentin etching, Permabond 910 cyanoacrylate adhesive, and Gluma bonding system. The bonded roots were maintained in a wet sponge. One week later the roots were re-fractured in the Instron machine, and the forces were recorded (RF). Each one of F, RF, A, and the ratios RF/F and RF/A were compared statistically among the three experimental groups. Overall, RF was at the most 20% of F. Statistically significant differences were obtained only in RF, RF/F, and RF/A (p < 0.0003). Roots bonded with Ionos cement demonstrated significantly lower values than roots bonded with Permabond and Gluma, both of which did not differ significantly. It was concluded that roots bonded with Ionos cement were the least resistant to re-fracture, due to a lesser bonding strength of Ionos bone cement as compared with Permabond and Gluma.

Bonding of enamel-dentin crown fragments after crown fracture. An experimental study using bonding agents

Previous experimental studies into the use of dentin bonding agents for reattachment of enamel-dentin crown fragments have demonstrated fracture strength about 50-60% of that of intact teeth. In the clinic this has been reflected in the frequent need of repeated bonding of the treated incisors due to refracture. Recently newer bonding agents have been developed which can bond equally well with enamel and dentin. Employing the same experimental model, these bonding agents (All-Bond 2, Scotchbond MP) were used to reattach crown fragments to the remaining portion of sheep incisors. Loading of teeth bonded with these agents in an Instron testing machine at a speed of 1 mm/min demonstrated similar fracture strengths as those previously achieved with Gluma, Scotchbond 2 or Tenure. A second study was carried out whereby fragments were bonded with Scotchbond MP and loaded at various speeds. The results demonstrated that the fracture strength decreased exponentially with increased loading speed. By extrapolation, it was concluded that the strength was nil at a loading speed of approximately 2 m/min. It was concluded that the weak link in the bond between tooth fragment and remaining tooth structure is the bonding resin. Theoretically, a resin which is slightly elastic might act as a shock absorber to withstand functional stress. However, studies carried out with resins of varying moduli of elasticity gave disappointing results probably due to their low flexural strength.(ABSTRACT TRUNCATED AT 250 WORDS)

Reattaching fractured tooth segments: an esthetic alternative

Reattaching fractured tooth segments offers an esthetic transitional restorative alternative to bonded composite and full crowns. The authors review this technique and demonstrate its application.

Treatment of crown fractured incisors with laminate veneer restorations. An experimental study

A method is described by which crown fractured incisors are restored with cast ceramic (Dicor) laminate veneers after initial treatment with either reattachment of the original crown fragment with a dentin bonding agent, with a composite resin build-up or no treatment (i.e. the veneer alone is used to restore the incisal edge). In order to elucidate the effect of the fragment/composite-tooth bonding interface on fracture strength of the restored teeth, the fracture strengths of the various treatment groups were compared to that of intact teeth supplied with Dicor laminate veneers. In an experimental investigation using central and lateral incisors from sheep, it was found that fracture strength (16.6 +/- 4.2 MPa) equal to that of intact incisors (16.1 +/- 2.6 MPa) could be achieved using laminate veneers made of porcelain on fractured teeth whose crown fragments were reattached using a dentin bonding agent (5). In the present investigation, using the same experimental model but using cast ceramic (Dicor) laminate veneers, the fracture strength of the restored incisors was significantly increased (21.0 +/- 3.7 MPa), exceeding that of intact teeth. The fracture strength of intact teeth was also exceeded in veneered incisors which were initially restored with a conventional composite resin build-up (20.2 +/- 5.6 MPa). However, the greatest fracture strength (28.2 +/- 8.9 MPa) was achieved when a Dicor laminate veneer alone was used to restore the fractured incisal edge.(ABSTRACT TRUNCATED AT 250 WORDS)