Shear bond strengths of tooth fragments reattached or restored

Evaluation of Fracture Resistance of Reattached Tooth Fragments Restored Using Fiber-reinforced Composites: A Systematic Review

AIM AND BACKGROUND

This systematic review examined the current literature to evaluate the fracture resistance of the tooth fragments reattached using fiber-reinforced composites (FRC).

MATERIALS AND METHODS

An electronic search was performed on Scopus, PubMed, and Web of Science databases according to specific inclusion and exclusion criteria to identify relevant articles to be included until January 2023. Articles with full text available in the English language for randomized control studies, observational studies, retrospective studies, and in vitro studies conducted on permanent human teeth were selected. The risk of bias was assessed in all studies using the OHAT tool.

RESULTS

Out of 16 search results, seven in vitro studies with a total of 415 samples were included in the review. Three studies reported that reinforcement using rigid FRC posts improves fracture resistance of reattached anterior teeth, three studies reported that reinforcement using flexible fiber bundles enhances the fracture strength of reattached posterior teeth and one study reported that the use of flexible polyethylene fibers improves fracture resistance in molars with reattached cusps.

CONCLUSION

Within the limitations of the studies included in the review, there is low-quality evidence that reinforcement of reattached fragments using FRC posts or fibers improves fracture resistance.

CLINICAL SIGNIFICANCE

The reattached fractured fragments may be susceptible to re-fracture. The use of FRC to reinforce the resin composite used for reattachment may enhance the bond strength and increase resistance to fracture. How to cite this article: Albar NHM. Evaluation of Fracture Resistance of Reattached Tooth Fragments Restored Using Fiber-reinforced Composites: A Systematic Review. J Contemp Dent Pract 2024;25(6):605-615.

An assessment of Brazilian dentists' knowledge about tooth fragment reattachment: A cross-sectional study

BACKGROUND/AIM

Crown fractures are common traumatic dental injuries and tooth fragment reattachment is a viable option for restoring a fractured tooth. The aim of this study was to assess the knowledge and experience of dentists in the Federal District regarding the tooth fragment reattachment technique for enamel and dentin fractures.

MATERIALS AND METHODS

For the cross-sectional observational study, an electronic form was designed with objective and self-report questions for dentists. The data were analyzed using descriptive statistics, with their absolute and relative frequencies. For the analysis of categorical variables, the nonparametric chi-squared or Fisher exact association tests were used in the statistical software R (version 4.2.1).

RESULTS

A total of 416 dentists participated in the study (58.9% female and 41.1% male). Of these, 70% declared they knew about fragment reattachment, but only 42.3% reported previous experience with this procedure. The most common storage medium used for the fractured fragment was milk (78.1%), and the bonding material used for reattachment was light-cured composite resin (86.3%). A majority (66.3%) reported that for a patient with enamel and dentin fracture, with the crown fragment in good condition, they would choose to do the reattachment.

CONCLUSION

Dentists demonstrated that they had adequate knowledge about the tooth fragment technique, although many did not have previous experience with this procedure.

Shear Bond Strength of Lithium Disilicate Bonded with Various Surface-Treated Titanium

Purpose

Retention is one of the most important factors for fixed dental prostheses, especially in implant dentistry. Accordingly, the goal of this study was to evaluate the level of shear bond strength between titanium (Ti) subjected to different surface treatments and lithium disilicate glass-ceramics.

Materials and Methods

In this work, 90 titanium alloy specimens were divided into six groups as follows: the control group (CT), 50 μm alumina airborne-particle abrasion group (SB), silica-coated group (CJ), anodization group (AN), anodization followed by alumina 50 μm airborne-particle abrasion group (ANSB), and anodization followed by silica coating group (ANCJ). Titanium specimens were bonded to lithium disilicate specimens with resin cement (Multilink N). The specimens were restored in water at 37°C for 24 h, and then, shear bond strength (SBS) tests were performed using a universal testing machine (Shimadzu, Japan). The SBS values were statistically analyzed. The failure mode of the debonded titanium was classified after viewing the samples under a stereoscope.

Results

The results demonstrated that the mean SBSs of CT and AN were significantly lower than those of the other groups (p < 0.05). The SB group showed the highest SBS (29.47 ± 2.41 MPa); however, there was no significant difference between SB, ANSB, ANCJ, and CJ. The stereoscopic analysis demonstrated that the failure mode of AN was predominantly adhesive failure; whereas, the other groups showed cohesive and mixed failures.

Conclusions

In this study, it was found that the surface treatment with 50 μm alumina airborne-particle abrasion, silica coating with Cojet™ sand, anodization followed by 50 μm alumina airborne-particle abrasion, and anodization followed by silica coating with Cojet™ sand improved the SBS between titanium and lithium disilicate luted with Multilink N resin cement.

Multidisciplinary Approach to Complicated Crown-root Fracture Treatment: A Case Report

Treatment of complicated crown-root fractures is one of the most challenging within the various types of dental trauma and requires a multidisciplinary approach. This paper reports the complicated crown-root fracture of a maxillary right central incisor, in which there was esthetic, functional, and biologic (endodontic and biologic width invasion) involvement. A 15-year-old male patient presented to the dental clinic one month after suffering trauma with a complicated crown-root fracture on tooth 8. The patient had previously undergone endodontic treatment and was sent to have periodontal surgery to reestablish the biological width on the palatal surface. Following the surgery, a fiberglass post was cemented, and the fragment was reattached. This approach allows the exposure of the cervical margin, adequate isolation, and subsequent fragment reattachment in the same clinical appointment. Fragment reattachment is a viable approach as it is a simple and conservative procedure that restores the natural esthetic of the tooth and has superior resistance compared to a composite restoration. The patient's cooperation in understanding the limitations of the treatment and maintaining adequate oral hygiene are very important to achieving a good prognosis of the case. After a 2-year clinical and radiographic follow-up period, the clinical protocol was found to be successful, and the tooth remained functional, esthetically favorable and asymptomatic.

Knowledge, awareness and perception amongst dental practitioners towards natural tooth fragment reattachment procedures in clinical practice-A cross-sectional survey

BACKGROUND/AIM

Reattachment of a tooth fragment is a viable alternative to restore a fractured tooth. The aim of this study was to assess the knowledge, awareness and perception of dental practitioners towards tooth fragment reattachment procedures.

MATERIAL AND METHODS

The cross-sectional study was conducted during 2019 and comprised dental practitioners working as general dentists or dental specialists. The subjects were asked to fill out a self-administered questionnaire. Questions related to knowledge and practice regarding fragment reattachment procedures were asked, and the responses were recorded. SPSS version 20.0 and the chi-square test were selected as the statistical tools for data analysis with significance level established at p < .05.

RESULTS

Eight hundred and fifty-seven subjects participated in the study. Of them, 404 (47%) were general dentists and 453 (53%) were specialist dentists. Out of the 857 subjects, 231 (27%) had clinical experience of less than 5 years, 268 (31.3%) between 5 and 10 years, 190 (22%) between 10 and 20 years and 168 (19.6%) had experience of over 20 years. Of the 857 subjects, 673 (78.5%) had some knowledge about the reattachment procedure and 292 (34.1%) had performed reattachment in clinical practice. The most common storage medium used for the fractured fragment was saline. The bonding material used for reattachment was lightcured composite resin. A subsequent fracture of the reattached fragment was encountered by more than 62% of the subjects.

CONCLUSIONS

Lack of availability of the fragment and lack of clinical training were the major reasons for clinicians not performing the procedure routinely. The attachment procedure was most often performed by both general dentists and specialist dentists with 5-10 years of clinical experience. Furthermore, the majority of the participants did not have any familiarity with the concept of biological restorations. Cross contamination was a major clinical concern for the limited clinical application of biological restorations.

Effect of Luting Cements On the Bond Strength to Turkom-Cera All-Ceramic Material

BACKGROUND:

The selection of the appropriate luting cement is a key factor for achieving a strong bond between prepared teeth and dental restorations.

AIM:

To evaluate the shear bond strength of Zinc phosphate cement Elite, glass ionomer cement Fuji I, resin-modified glass ionomer cement Fuji Plus and resin luting cement Panavia-F to Turkom-Cera all-ceramic material.

MATERIALS AND METHODS:

Turkom-Cera was used to form discs 10mm in diameter and 3 mm in thickness (n = 40). The ceramic discs were wet ground, air - particle abraded with 50 - μm aluminium oxide particles and randomly divided into four groups (n = 10). The luting cement was bonded to Turkom-Cera discs as per manufacturer instructions. The shear bond strengths were determined using the universal testing machine at a crosshead speed of 0.5 mm/min. The data were analysed using the tests One Way ANOVA, the nonparametric Kruskal - Wallis test and Mann - Whitney Post hoc test.

RESULTS:

The shear bond strength of the Elite, Fuji I, Fuji Plus and Panavia F groups were: 0.92 ± 0.42, 2.04 ± 0.78, 4.37 ± 1.18, and 16.42 ± 3.38 MPa, respectively. There was the statistically significant difference between the four luting cement tested (p < 0.05).

CONCLUSION:

the phosphate-containing resin cement Panavia-F exhibited shear bond strength value significantly higher than all materials tested.

Fracture Resistance of Incisal Fragments Following Reattachment With Different Techniques in Simulated Crown Fractures

Introduction: The aim of the present study was to evaluate and compare the effect of acidetching and Er, Cr:YSGG laser treatment before the reattachment of incisal fragments in coronal fractures of permanent incisor teeth. Methods: Sixty-six sound human maxillary incisors were randomly divided into 3 groups (n=22). Teeth were embedded in self-cure acrylic resins by leaving one-third of the crowns out, and uncomplicated crown fractures were obtained using an Instron testing device. The fragments were reattached using 3 different procedures and a hybrid resin composite (Z250): Group I: Acid etching + Prime & Bond NT; Group II: Er,Cr:YSGG + Prime & Bond NT; Group III: Er,Cr:YSGG + Acid etching + Prime & Bond NT. The percentages of shear bond strengths were determined by comparing fracture strengths of sound and reattached teeth for 3 groups. All data were analyzed statistically with Kruskal-Wallis H test. Results: Mean fracture strengths of the reattached fragments were between 51.02% and 62.93% of that of the sound teeth in all groups. Group I had significantly higher percentages of shear bond strength values (P<0.05) when compared to group II and group III. No significant difference (P>0.05) was found between group II and group III. Conclusion: The findings of the present study show that Er,Cr:YSGG laser irradiation prior to the reattachment of incisal fragments has a negative effect on fracture strength.

Etiologic factors and clinical evaluation of restored fractured anterior teeth: an observational study

Purpose:

The aims of this study were to investigate the etiologic factors and to evaluate performance of composite resin on fractured crown in permanent anterior teeth at 6 and 12 months.

Subjects and Methods:

Records from 51 patients were retrieved from a Dental School Clinic, comprising 73 fractured anterior teeth directly restored with a submicron hybrid composite (Spectrum TPH) resin and respective adhesive system (Prime and Bond NT) were evaluated. The United States Public Health Service criteria were used to assess the clinical evaluation. Data were analyzed using the Wilcoxon Signed Rank, Kruskal–Wallis, Mann–Whitney U, and Siegel and Castellan tests.

Results:

Seventy-two maxillary incisors and one canine of 51 patients were evaluated. The patient’s age at the time of therapy ranged from 14 to 64 years old (mean 25.47). Mostly observed crown fracture was seen in upper incisors (84.9%) and due to falls (58.8%). At the 6-month follow-up, one patient lost one restoration and at the 12-month, one patient lost one and one lost two restorations. A statistically significant difference was found in terms of marginal adaptation between 6 and 12 months.

Conclusion:

In this short-term observation period, remaining tooth structure was conserved and good patient compliance was achieved. Factors such as esthetic and/or cost should be considered to indicate the direct composite restorations.

Biological restoration in pediatric dentistry: a brief insight

Dental caries is the most prevalent disease in humans, especially during early childhood. The restoration of such an extensive carious lesion should be done properly to reestablish their anatomy and hence their masticatory, phonetic, esthetic and space-maintainer functions in the dental arches. The consequences of premature loss of primary teeth are well known, namely the loss of vertical dimension of occlusion, tongue thrusting and mouth breathing habits, which can be the sources of future malocclusion. Satisfactory restoration of these teeth, improving esthetics, along with the management of space and function has always been a challenge for pediatric dentist. An ever increasing demand for esthetics has led to innovation and development of newer treatment modalities for these problems. In an attempt to widen the treatment options as biologically and conservatively as possible, tooth structure is used as a restorative material to rehabilitate severely destroyed tooth crowns. This technique consists of bonding sterile dental fragments, obtained either from the patient or from a tooth bank, to the teeth. Such a technique was termed as ‘biological restoration’.

This article aims at reviewing the evolution, techniques and outcome of such biological restorations.

How to cite this article: MD Indira, Dhull KS, Nandlal B, Kumar PSP, Dhull RS. Biological Restoration in Pediatric Dentistry: A Brief Insight. Int J Clin Pediatr Dent 2014;7(3):197-201.

Dental fragment embedded in the lower lip after facial trauma: Brief review literature and report of a case

Upper incisors are the most frequently involved teeth in traumatic dental injuries. Soft tissues (lips and/or oral mucosa) adjacent to incisal edge can receive direct and/or indirect traumas. Laceration of the lower lip is a not rare eventuality and teeth fragments could be embedded in labial soft tissue. The reattachment of these fragments, if possible, is the elective treatment choice, thanks to the modern adhesive and restorative techniques. The authors present a case of a white Caucasian 10-year-old child, who attended the dental clinic for the treatment of both upper central incisors’ crown fractures. The fragment of the left incisor was retrieved embedded in the lower lip. It was successfully surgically removed and reattached using a composite adhesive technique. A careful clinical and radiographic examination with the surgical removal of tooth fragments could prevent undesirable foreign body reaction, infection and scarring. The authors also reviewed the most relevant literature concerning tooth fragment reattachment after removal from oral soft tissues.

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.

Effect of storage environment on the bond strength of reattachment of crown fragments to fractured teeth

Aim:

The aim of this study was to examine various storage environments for storing fragments before being bonded to the remaining teeth and also estimate the required force to fracture the restored teeth.

Materials and Methods:

Sixty mandibular incisor teeth were fractured on the incisal one-third and were divided into five groups of 12 each to be stored in normal saline, water, milk, saliva and dry environments for 24 hours. All the fractured parts in each group were bonded to their relevant apical parts by an etch and rinse bonding system and a flowable composite resin. The fracture resistance was measured by a universal testing machine, and the results were analyzed using one-way ANOVA and Tukey statistical tests.

Results:

The results revealed that the difference among the five groups was statistically significant (P<0.001). Tukey tests showed that the force required for fracturing fragments kept in the milk and saliva environments were significantly higher than those for the normal saline, water and dry environments (P<0.05 ).

Conclusions:

It was concluded that keeping the fractured parts in milk and saliva environments can increase the required force for fracturing teeth more than the other environments.

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.

Fracture resistance of microhybrid composite, nano composite and fibre-reinforced composite used for incisal edge restoration

Traumatized anterior teeth need quick, aesthetic and functional repair. Along with aesthetics, the physical properties of restorative material should also be considered for long-lasting restoration. Fibre reinforcement has been tried as a newer technique to improve the physical properties of composite materials. Hence, this study was carried out to evaluate the fracture resistance of microhybrid composite, nano composite and fibre-reinforced composite used for restoration of incisal edge of fractured maxillary central incisors. Extracted permanent maxillary central incisors were randomly divided into four groups of 10 samples each: control group with intact teeth (Group A), microhybrid composite (Esthet X; Dentsply/Caulk, Milford, DE, USA) (group B), nano composite (Ceram X; Dentsply/Caulk) (group C) and microhybrid composite reinforced with polyethylene fibre - flowable composite unit [(Ribbond THM; Ribbond Inc., Seattle, WA, USA; Esthet X flow; Dentsply/Caulk)] (group D). The fracture resistance was measured under universal testing machine at a speed of 1mmmin(-1) with the loading tip of 2mm diameter. The samples were further evaluated for mode of fracture under stereomicroscope at 3.5× magnification. The data were analysed using one-way anova and Tukey's test for fracture resistance. Group A and group D exhibited significantly higher fracture resistance than group B and group C. No significant difference was found between group B and group C as well as between group A and group D. Fisher's exact test for the mode of fracture revealed no statistical significance. It was concluded that fibre reinforcement of composite could be an alternative technique for restoration of fractured anterior teeth for better aesthetics and longevity of the restoration.

Clinical management of a fractured anterior tooth with reattachment technique: a case report with an 8-year follow up

Fracture of anterior teeth is a relatively common outcome of trauma to the teeth. If the fractured teeth fragments are recovered by the patient and brought to the dental office within reasonable time, the fragments may be reattached to the remaining tooth structure. This article presents a case of a 15-year-old male patient with fractured left maxillary lateral incisor. The fragment reattachment was performed using dual-cured composite resin cement and the treatment outcomes of an 8-year follow up were presented. The technique described in this case report for reattachment of the fractured fragments is simple, while restoring providing long-lasting esthetics and improved function with a very conservative approach.

Alternative treatment procedure in the case of fractured abutment of adhesive bridge: a clinical report

In this case report, an alternative approach was presented for treatment of coronal fracture including pulp of maxillary central incisor, one of the abutments of an adhesive bridge, by using fiber post and tooth's own fractured component. The patient was referred to our clinic with the complaint of pain from the upper right central incisor and mobility of the adhesive bridge in maxillary anterior segment. It was realized that, the upper right central incisor, one of the abutments of the adhesive bridge, had been fractured at middle thirds of the crown including the pulp chamber. After dismounting the adhesive bridge and completion of the root canal treatment, a fiber post was placed into the fractured tooth. The fractured component, adherent to adhesive bridge retainer, was concorded to the fiber post. The whole structure was cemented with adhesive resin. A 1-mm-wide groove was made along the fracture line and restored with composite resin. The patient was evaluated clinically and radiographically at 12 and 30 months after the treatment.

CLINICAL SIGNIFICANCE

Adhesive cementation of fractured component by supporting the remaining tooth structure with a fiber post is an inexpensive and conservative treatment alternative when the fractured component is compatible with the remaining tooth structure in cases of tooth fractures including the pulp chamber at anterior segment.

Reattachment of anterior fractured teeth: effect of materials and techniques on impact strength

BACKGROUND/AIM

The reattachment of dental fragments, as a conservative treatment, should be the first choice to restore fractured teeth. Therefore, the aim of this study was to evaluate the effect of different materials and reattachment techniques on impact strength of bovine incisors.

MATERIAL AND METHODS

Standardized fragments were obtained when 80 crowns were sectioned 12 mm from the incisal edge. Teeth were mounted in PVC rings, embedded in acrylic resin and polyether to simulate bone support and periodontal ligament. Specimens were distributed in nine groups (n = 10), according to the reattachment technique (Direct bonding or Circumferential chamfer); the adhesive system (Single Bond or Clearfil SE Bond); and the intermediated material (Filtek Z350 Flow or Rely X CRA). Sound teeth composed the control group. Circumferential chamfer was prepared after the bonding of the fragment by means of a spherical point and filled with the composite Filtek Z250. The impact strength was evaluated in a universal testing machine Instron. A compressive load was applied at a crosshead speed of 500 mm min(-1) on the buccal surface, 2 mm from the incisal edge. Data were submitted to anova and Ryan-Einot-Gabriel-Welsch Multiple Range test (5%).

RESULTS

Mean value of impact strength for control group was 64.8 Kgf. The fragment reattachment using Circumferential chamfer was significantly superior to Direct Bonding. The use of Single Bond significantly increased the impact strength when compared to the use of Clearfil SE. There was no significant difference among Rely X and Filtek X350 Flow.

CONCLUSION

No technique or material, when individually considered, was capable of achieving the mechanical strength of the sound teeth; however, the association of reattachment technique Circumferential chamfer with bonding system Single Bond could approximate the immediate impact strength of the restored teeth to that observed in the sound teeth.

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.

Bond strength of adhesively luted ceramic discs to different core materials

The purpose of this in vitro study was to compare the shear bond strengths of resin, glass-ionomer, and ceramic-based core materials to all ceramic discs. Five core materials (Core max, Sankin; Clearfil AP-X, Kuraray; Empress Cosmo, Ivoclar-Vivadent; Photocore, Kuraray; Dyract Extra, Dentsply) were prepared as discs 10 mm in diameter and 2 mm in height according to the manufacturer's instructions. Ten disc specimens per group were prepared, and dentin served as the control. All resin specimens were embedded in autopolymerizing acrylic resin, with one surface facing up. All ceramic discs (IPS Empress I, Ivoclar-Vivadent) 3 mm in diameter and 2 mm in height were prepared and bonded to core specimens with a dual-curing luting resin cement (Variolink II, Vivadent). Specimens were stored in distilled water at 37 degrees C. Shear bond strength of each sample was measured after 24 h using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with one-way analysis of variance and Tukey HSD tests (alpha = 0.05). Shear bond strength varied significantly depending on the core material used (p < 0.05). Clearfil AP-X and Photocore showed the highest shear bond strength value while Empress Cosmo provided the lowest (p < 0.05). There were no statistically significant differences among Clearfil AP-X, Photocore, and Core-Max (p > 0.05). And also there were no statistically significant differences between Dyract Extra and the control group (p > 0.05). In vitro shear bond strengths of ceramic discs bonded to resin-based core materials showed higher bond strength values than ceramic-based core material.

Fractured incisors: a judicious restorative approach--Part 2

AIM

To consider different conservative options in the literature to restore fractured anterior teeth.

MATERIALS AND METHODS

Only anterior tooth fractures not involving the pulp were considered, without limitation on age. Treatment options were chosen depending on the clinical situation of patients at first visit. The authors considered 15 cases each of: reattachment; porcelain veneers; direct composites.

RESULTS AND CONCLUSIONS

The techniques analysed were revealed to be valid during the period of observation. No failures were recorded with vital teeth keeping their vitality and no radiographic signs of apical or root pathology. With reattachment, two cases have shown the visibility of fracture line after two years, depending on the angle of light incidence on the tooth surface. For direct restorations, three adult cases have shown partial discolouration at 24, 28 and 40 months. No fractures or debonding have occurred among porcelain veneers. The authors suggest, whenever possible, to utilise the reattachment technique. Direct restorations are suitable for young patients: they have a higher chance of sustaining further trauma than adults, and composites have a favourable failure mode compared to ceramics. In adults, where long-lasting restorations are needed, restoration with porcelain veneers is the treatment of choice.

Biological restorations as a treatment option for primary molars with extensive coronal destruction: report of two cases

This article reports the cases of two young children aged 4 and 5 years, in whom biological restorations using tooth fragments were placed in primary molars with severely damaged crowns due to extensive carious lesions. After radiographic and clinical evaluation, tooth fragments obtained from extracted teeth in stock were autoclaved, adjusted to the prepared cavity and bonded to the remaining tooth structure with either adhesive system (Case 1) or dual-cure resin-based cement (Case 2) over a calcium hydroxide layer and a glass ionomer cement base. Occlusal adjustment was performed and topical sodium fluoride was applied to tooth surface. Periodical clinical and radiographic controls were carried out and the restored teeth were followed up for 4 and 3 years, respectively, until exfoliation. In these two reports, the technical aspects are described and the benefits and disadvantages of biological restorations as an alternative treatment for rehabilitation of severely destroyed primary molars are discussed.