title: Shear bond strength of precoated orthodontic brackets: an in vivo study Orthodontic in vivo bond strength: comparison with in vitro results. Effect of a self-etching primer on shear bond strength of adhesive precoated brackets in vivo. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. Effects of conventional and high-intensity light-curing on enamel shear bond strength of composite resin and resin-modified glass-ionomer. In vivo debonding strength and enamel damage in two orthodontic debonding methods. Argon laser vs conventional visible light-cured orthodontic bracket bonding: an in-vivo and in-vitro study. Influence of force location in orthodontic shear bond strength testing.
abstract: Objective To evaluate the shear bond strength of precoated orthodontic brackets bonded with self-etching primer relative to that of noncoated conventionally-bonded brackets at two different time intervals . Methods Twenty-one subjects were selected for r and omized split-mouth bonding of two types of brackets to the maxillary arch . Half of the teeth had precoated brackets bonded using self-etching adhesive , and the other half had regular brackets bonded using Transbond XT adhesive . Nitinol wires were tied to the upper arch and were left until the time of debonding . The patients were r and omly divided into two groups : one debonded after one hour and the other debonded two weeks after the initial wire placement . The shear bond strength was directly recorded from the patients ’ mouths using an in vivo debonding device . Results There were no significant differences in shear bond strength between the precoated and conventional groups or within each group at different time intervals . There were significant differences between anterior and posterior teeth in both the precoated and conventional groups . Conclusion Pre-coated brackets bonded with self-etching adhesive have the same bonding strength as the conventionally bonded brackets The purpose of the present study was to test a new in vivo debonding device and compare in vivo bond strengths recorded by this device with in vitro bond strengths recorded by a universal testing machine such as the Instron . For the in vitro part of the study , 60 extracted premolar teeth were divided into 2 groups of 30 each . Both groups of 30 teeth had 3 M Unitek Victory Twin brackets , precoated with Transbond XT composite resin , bonded to them . Shear bond strength tests were carried out in vitro using the universal testing machine on one group of 30 teeth while the debonding device was used on the other group of 30 teeth . The mean shear bond strength of the group debonded using the universal machine was 11.02 MPa and that of the group debonded with the debonding device was 12.82 MPa . For the in vivo part of the study , 8 patients r and omly assigned to the research clinician from patients in The University of Alabama School of Dentistry , Department of Orthodontics , had a total of 60 premolar teeth bonded with 3 M Unitek Victory Twin brackets . Following comprehensive orthodontic treatment ( average time of 23 months ) , shear bond strength tests were carried out using the debonding device , which can measure debonding forces in vivo . The mean shear bond strength recorded in vivo was 5.47 MPa . Statistically significant differences were found between all 3 groups tested . The results appear to indicate that mean bond strengths recorded in vivo following comprehensive orthodontic treatment are significantly lower than bond strengths recorded in vitro The aim of this study was to evaluate the influence of a self-etching primer ( SEP ) ( Transbond Plus SEP , 3 M Unitek , Monrovia , Calif ) on shear bond strength of adhesive uncoated and precoated Victory brackets ( 3 M Unitek ) . The sample group consisted of 23 patients , with four premolars each , equally divided in four different groups . Brackets were bonded in vivo by the same operator using a split-mouth r and om technique : group 1 , 37 % phosphoric acid + primer + composite + conventional Victory bracket ; group 2 , 37 % phosphoric acid + primer + precoated Victory bracket ; group 3 , SEP + composite + conventional bracket ; group 4 , SEP + precoated bracket . After 30 days , premolars were extracted for orthodontic reasons and a Universal Instron Machine was used to apply an occlusal shear force directly to the enamel-bracket interface at a speed of 0.5 mm/min . The groups were compared using two-way analysis of variance . Mean results and st and ard deviation for the groups were : group 1 = 11.60 + /- 2.65 Mpa , group 2 = 9.79 + /- 2.71 Mpa , group 3 = 10.75 + /- 2.67 Mpa , and group 4 = 10.31+/- 2.70 Mpa . No difference was observed between the conventional etching and primer or SEP ( P = .948 ) . However , significant differences in bond strength were present between the uncoated and precoated brackets ( P = .032 ) . Considering the values required to withst and normal orthodontic forces ( 8 - 9 Mpa ) , it could be concluded that the SEP combined with adhesive precoated brackets showed adequate shear bond strength and may be suitable for clinical use OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity The purpose of this study was to evaluate the shear bond strengths of a composite resin ( Transbond XT ; 3M/Unitek , Monrovia , Calif ) and a resin-modified glass ionomer ( Fuji Ortho LC ; GC America Inc , Alsip , Ill ) cured with 2 different light-curing units : a conventional visible light unit ( Ortholux XT ; 3 M Dental Products , St Paul , Minn ) and a xenon arc light unit ( Plasma Arc Curing [ PAC ] System ; American Dental Technologies , Corpus Christi , Texas ) . One hundred twenty freshly extracted bovine permanent m and ibular incisors were r and omly divided into 1 of 8 groups ; each group consisted of 15 specimens . Two groups ( 1 group for each type of adhesive ) were exposed to the visible light for 20 seconds ( Transbond XT ) and 40 seconds ( Fuji Ortho LC ) , respectively , and used as control groups . The remaining 6 groups ( 3 for each adhesive ) were cured with the xenon arc light for 2 , 5 , and 10 seconds . After bonding , all sample s were stored in distilled water at room temperature for 24 hours and subsequently tested in a shear mode on an Instron universal testing machine ( Instron Corp , Canton , Mass ) . For the groups bonded with Transbond XT , no statistically significant differences ( P = .868 ) were found between the shear bond strength of the control group cured with Ortholux XT and those of the groups cured with the PAC System for 2 , 5 , or 10 seconds . When the shear bond strengths of the groups bonded with Fuji Ortho LC were evaluated , no statistically significant differences ( P = .087 ) were found between the control group that was cured with Ortholux XT and those cured with the PAC System . The bond strength of the composite resin was significantly higher than that of the resin-modified glass ionomer in all the groups tested ( P < .0001 ) . The present findings indicate that , compared with visible light-curing , the xenon arc light enables the clinician to significantly reduce the curing time of both bonding agents , without affecting their shear bond strengths . Therefore , xenon arc light sources can be recommended as an advantageous alternative for curing both composite resins and resin-modified glass ionomers Bracket debonding strength related to diverse debonding methods and enamel damage has not been assessed in vivo . The study hypothetized a direct relationship between these three parameters . Debonding strength was measured clinical ly in the wings method and base method on 50 patients in a split mouth method using a calibrated debonding plier . Brackets from 30 of these patients were scanned in SEM and EDAX for adhesive remnant index and enamel calcium remnants . Base method debonding force was significantly greater than wings method ( 163.5+/-68.7 N , 106.1+/-66.2 N , respectively , p < 0.001 ) . A positive adhesive remnant index score was found in both methods ( 68.7 % , 66.7 % , respectively ) . Debonding strength vs. adhesive remnant index or calcium index scores were not correlated . However , the latter two were significantly correlated ( 0.524 < R < 0.895 , p < 0.031 ) . Half of the debonding failures developed at the adhesive enamel interface . The results warnts the potential of enamel damage during debonding INTRODUCTION Many advantages of argon lasers have been reported , including high-speed orthodontic adhesive curing and less enamel demineralization . The purpose of this study was to compare bond strengths after curing with the argon laser ( 10 seconds ) and the conventional curing light ( 40 seconds ) in vivo and in vitro . METHODS Four premolars from each of 23 volunteers were r and omly assigned to either the argon laser group or the conventional light group for the in-vivo study . Shear bond strengths were measured after 14 days with custom- design ed debonding pliers . In-vitro bond strengths were measured by using 4 premolars from each of 25 volunteers .  Shear bond strength was measured after 14 days of thermocycling with the same protocol as the in-vivo study . Adhesive remnant index scores ( ARI ) were determined . RESULTS No significant differences were found in bond strengths according to curing method , dental arch , or sex . In-vivo results were significantly lower ( P < .05 ) than in-vitro results . A significant ( P < .05 ) difference in ARI scores between the curing methods was determined ; no significant correlation between mean bond strengths and ARI scores was determined . CONCLUSIONS Bond strength for argon laser curing is comparable to conventional light curing and is sufficient for clinical applications . Although the argon laser left more adhesive on the tooth surfaces on debonding , there was no increase in enamel surface fractures OBJECTIVE The purpose of the present study was to analyze the influence of debonding force location in shear bond strength testing of orthodontic brackets in vitro . METHODS Ninety extracted permanent bovine m and ibular incisors were r and omly divided into 3 groups of 30 specimens each . Teeth were bonded with stainless steel orthodontic brackets . Enamel surfaces were etched with 37 % phosphoric acid for 30s and bonded with a composite adhesive .  Debonding force measurements were performed with a universal testing machine . Location of the debonding force was : bracket base ( group A ) , ligature groove ( group B ) , occlusal bracket wings ( group C ) . RESULTS Mean shear bond strength measurements were as follows : 22.70(4.23)MPa ( group A ) , 11.52(2.74)MPa ( group B ) , 9.44(2.96)MPa ( group C ) . Analysis of variance indicated that there were significant differences in shear bond strength . Post-hoc Tukey tests showed that bond strength measurements of group A were significantly different from those of groups B and C. The adhesive remnant index also showed significant differences and ranged from a mean of 1.53 in group A to a mean of 2.10 in group C. SIGNIFICANCE Debonding force location had a significant influence on shear bond strength measurements and bond failure pattern , indicating that this parameter needs to be taken into consideration for inter study comparison of in vitro results
target: The review reached no real conclusion apart from the lack of efforts to clinical ly evaluate the bonding efficiency of a wide range of orthodontic bracket-adhesive systems in terms of debonding force compared to laboratory-based in vitro and ex vivo studies
background: The aim of this study was to systematic ally review the available studies measuring the bond strength of  orthodontic bracket-adhesive system  under different experimental conditions in vivo .