Tooth color change due to different etching and debonding procedures

Objectives:To compare the effects of different etching techniques, 12–, 24–bladed tungsten carbide burs, and polishing discs on tooth color changes during orthodontic treatment.Materials and Methods:59 individuals (mean age: 15.20 ± 1.59 years) were divided into four groups: 37% phosphoric acid and adhesive primer was used in Groups I and II whereas self–etch primer was used in Groups III and IV for enamel preparation. After orthodontic treatment, residual adhesives were cleaned with 12–bladed tungsten carbide burs in Groups I and III, while 24–bladed tungsten carbide burs were used in Groups II and IV. All teeth were polished with medium and fine Sof–Lex XT discs (3M ESPE, St Paul, Minnesota). Color measurements were taken from upper incisors and canines at pretreatment (T0), after cleaning with tungsten carbide burs (T1) and polishing with discs (T2). Wilcoxon test was used for evaluation of L*, a*, b* changes and Kruskal–Wallis for intergroup comparison of color changes.Results:L*, a*, b* values, except a* at Groups I, II, IV, and b* at Group III, changed significantly (P < .05). Groups III and IV showed significantly different color alterations from T0 to T1 (P < .05). After polishing, tooth color alterations were not significantly different among the groups.Conclusions:In self–etch bonding groups, a 12–bladed tungsten carbide bur caused less color change than the 24–bladed tungsten carbide bur. Orthodontic treatment resulted with visible and clinically unacceptable tooth color alterations regardless of the enamel preparation and clean–up techniques. Polishing reduced the effect of tungsten carbide burs, but did not affect the total influence of orthodontic treatment on the tooth color.     

Effects of different orthodontic adhesives and resin removal techniques on enamel color alteration

Objective: To investigate the color alterations in enamel following the use of different orthodontic bonding resins and adhesive residue–removal burs.Materials and Methods:Metal brackets were bonded to extracted human premolars (n  =  175) by using an etch-and-rinse adhesive system, a self-etch adhesive system (SEP), or a resin-modified glass ionomer cement (RMGIC). After 24 hours of photoaging, the brackets were removed and the adhesive residue on the tooth surfaces was cleaned with either a tungsten carbide bur or a Stainbuster bur. Tooth colors were measured with a spectrophotometer at baseline, after adhesive removal, and after additional photoaging. Color evaluation was made, and color differences induced by photoaging were calculated. Statistical evaluation was made using the Kruskal-Wallis test and the Mann-Whitney U-test, with Bonferroni correction.Results:All specimens showed discoloration at varying levels. The highest color change was observed in the etch-and-rinse adhesive/tungsten carbide bur group. When the etch-and-rinse and self-etch adhesives were used, adhesive-remnant removal with Stainbuster burs resulted in significantly lower discoloration. The type of bur did not affect the extent of enamel discoloration in the RMGIC group.Conclusions:Orthodontic treatment alters the original color of enamel, and both the adhesive system and the resin-removal methods are responsible for this change. When brackets are bonded with the etch-and-rinse system or the SEP, cleaning the adhesive residuals with Stainbuster burs is recommended for minimal change. RMGIC can be safely cleaned with tungsten carbide burs.     

两种方法去除正畸牙面树脂粘结剂的效果评价

目的 评价两种去除正畸粘结剂及处理釉质表面方法的效果,为临床去除釉质粘结剂提供参考。 方法 选择正畸拔除的前磨牙30个,常规粘结托槽后去除托槽,将其随机分为两组,每组15个,分别使用金钢砂车针和碳钨钻,磨除残留牙体表面粘结剂,记录操作所用时间,用抛光杯抛光后用原子力显微镜测定釉质表面的粗糙度。 结果 金刚砂车针和碳钨钻去除正畸粘结剂操作时间无明显差异, 实验结果显示用碳钨钻磨除粘结剂的釉质表面粗糙度明显小于金钢砂车针, 有明显统计学差异。结论 碳钨钻去除金属托槽粘结剂方法对牙面的影响小于金刚砂车针。     

Porcelain Surface Alterations and Refinishing After Use of Two Orthodontic Bonding Methods

Objective:To compare porcelain surfaces at debonding after use of two surface preparation methods and to evaluate a method for restoring the surface.Materials and Methods:Lava Ceram feldspathic porcelain discs (n  =  40) underwent one of two surface treatments prior to bonding orthodontic brackets. Half the discs had sandblasting, hydrofluoric acid, and silane (SB + HF + S), and the other half, phosphoric acid and silane (PA + S). Brackets were debonded using bracket removing pliers, and resin was removed with a 12-fluted carbide bur. The surface was refinished using a porcelain polishing kit, followed by diamond polishing paste. Measurements for surface roughness (Ra), gloss, and color were made before bonding (baseline), after debonding, and after each step of refinishing. Surfaces were also examined by scanning electron microscopy (SEM). Data was analyzed with 2-way ANOVA followed by Tukey HSD tests (α  =  0.05).Results:The SB + HF + S bonding method increased Ra (0.160 to 1.121 µm), decreased gloss (41.3 to 3.7) and altered color (ΔE  =  4.37; P < .001). The PA + S method increased Ra (0.173 to 0.341 µm; P < .001), but the increase in Ra was significantly less than that caused by the SB + HF + S bonding method (P < . 001). The PA + S method caused insignificant changes in gloss (41.7 to 38.0) and color (ΔE  =  0.50). The measurements and SEM observations showed that changes were fully restored to baseline with refinishing.Conclusions:The PA + S method caused significantly less damage to porcelain than the SB + HF + S method. The refinishing protocol fully restored the porcelain surfaces.     

Early versus delayed rebonding of orthodontic brackets

ObjectivesThere are controversial reports regarding the effect of repeated bonding on shear bond strength (SBS) of orthodontic attachments. The aim of this study was to evaluate the SBS of brackets following early and delayed rebonding, and after employing different methods of composite removal.Materials and methodsSixty eight premolars were randomly assigned into 4 groups. After initial debonding and recording the SBS, the adhesive remnants in the first group were removed by a round bur, in the second group by a green rubber wheel, and in the third and fourth groups by 12-fluted tungsten carbide burs, all of them connecting to a low speed handpiece. In the fourth group following adhesive removal, the teeth were kept in a simulated oral environment for one month. Then, rebonding was performed and the second SBS was measured. Two representative samples from each group were examined under a scanning electron microscope following adhesive removal. The data were analyzed by ANOVA, Paired sample t-test and Chi-Square test.ResultsIn the first group, the rebonding strength was decreased significantly (p < 0.05), while composite removal with a tungsten carbide bur or a green rubber wheel did not affect SBS significantly (p > 0.05). Late rebonding of brackets had no effect on the SBS (p > 0.05).ConclusionsPostponing rebonding to the next visit does not improve the SBS significantly. It is recommended to use a tungsten carbide bur or a green rubber wheel, and not a round bur for removing adhesive remnants following debonding of orthodontic brackets.     

Dental Burs—What Bur for Which Application? A Survey of Dental Schools

PURPOSE: The purpose of this study was to survey North American dental schools regarding recommendations for rotary instrumentation for fixed prosthodontic and operative procedures at the predoctoral and postgraduate level. MATERIALS AND METHODS: A 25-question survey was sent to 64 North American dental schools, of which 15 questions specifically related to rotary instrument recommendations. One questionnaire was addressed to the individual at each school having administrative responsibility for teaching tooth preparation techniques. A high response rate was assured by follow-up telephone calls and faxes. The distributions of bur recommendations for both predoctoral and advanced prosthodontic programs were analyzed by chi-squared tests at an a priori alpha = 0.05. RESULTS: Completed surveys were received from 58 of 64 dental schools, a response rate > 90%. Medium grit burs predominate in predoctoral education for gross tooth reduction for fixed prosthodontics, whereas coarse grit burs predominate at the graduate level (p < .05). The use of the diamond bur alone predominates for axial wall refinement, whereas the use of carbide burs or carbide burs in combination with diamond burs prevails for marginal refinement (p < .05). In predoctoral operative dentistry, recommendations for cavity outline form were similar at all dental schools (p > .05) and were principally tungsten carbide (WC) burs. Carbide burs are the instrument of choice for internal walls, but the WC bur alone or in combination with diamond burs is preferred for refining composite margins (p < .05). CONCLUSIONS: There is a broad consensus within North American dental schools on rotary instrumentation used by dental students. There is a greater use of coarser grit burs for gross tooth reduction in fixed prosthodontics at the postgraduate than predoctoral level.     

Effectiveness of diamond-impregnated felt wheels for polishing a hybrid composite

The effectiveness of diamond-impregnated felt wheels for polishing the surfaces of a fine-particle hybrid composite was studied in relation to different finishing methods. Standardised composite specimens were finished with one or a series of two or three finishing diamonds (particle size 30, 15 and 8 μm), one or two tungsten carbide finishing burs (12- and 30-fluted) or with a finishing diamond followed by a tungsten carbide bur. The final polishing of all specimens was done with the diamond-impregnated felt wheel Diafix α. Treatment with Sof-Lex discs after the use of a finishing diamond served as a polishing standard for comparison. Evaluation of the final surfaces was done with profilometry and by scanning electron microscopy. The profilometric results showed that the type of pretreatment was decisive for the quality of the final polishing. Nearly all surfaces polished by the diamond-impregnated felt wheels were smoother than those treated by the flexible discs (P<0.01). The lowest roughness data were recorded following a pretreatment with a finishing diamond and a tungsten carbide finishing bur. After appropriate pretreatment, the hybrid composite surface was sufficiently polished with the diamond-impregnated felt wheels.     

Enamel gloss changes induced by orthodontic bonding

ABSTRACT

Objective: The purpose of this study was to assess enamel gloss changes induced by orthodontic bracket bonding with a light-cured composite or a light-cured resin-reinforced glass ionomer cement.

Setting: The Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Greece.

Design: Laboratory study.

Methods: A total of twenty extracted upper human first premolars were included in this study and each tooth served as a control for itself. Their buccal surfaces were subjected to 60^o-angle gloss measurement (G%60) with a standardized and secure repeated analysis of the same site. After baseline evaluation, a bracket was bonded on the buccal surface of each tooth. Half of the specimens were bonded with acid-etching and a light-cured composite whereas the other half with a light-cured resin-reinforced glass ionomer cement without prior enamel conditioning. Gloss measurements were repeated after bracket debonding and removal of the composite/glass ionomer cement with an 18-fluted carbide bur. Gloss differences between the two measurement conditions (baseline and post-debonding) were analyzed through linear regression with standard errors derived using the bootstrap method. Level of significance was set at a?<?0.05.

Results: A statistically significant difference was detected between the tested groups for the outcome of interest. Teeth bonded with light-cured composite exhibited larger enamel gloss changes as compared to resin-reinforced glass ionomer cement (β?=?0.74; 95% CIs: 0.10, 1.38; p?=?0.02).

Conclusions: Bracket bonding with two common bonding protocols (acid-etching with a light-cured composite vs. no etching with resin reinforced glass-ionomer cement) and subsequently debonding and adhesive removal with an 18-fluted carbide bur induced enamel gloss changes.     

Assessing the cutting efficiency of different burs on zirconia substrate

Cutting dental zirconia for endodontic access preparation is difficult. Therefore, this study aimed to determine cutting efficiency of various burs when cutting this material. An air turbine handpiece was used in a customised test rig to cut sintered zirconia specimens, using a conventional blue band diamond, two different zirconia‐cutting diamond and a zirconia‐cutting tungsten carbide bur. Position and speed of the bur were continuously determined using wireless data acquisition over two successive five‐minute runs. Differences in cutting efficiency were statistically analysed. Burs were examined using light and scanning electron microscopy (SEM). All diamond burs cut zirconia more efficiently than the tungsten carbide bur. Overall, all burs showed decreasing cutting efficiency over time. SEM images showed discernible wear and damage to the cutting portion of each bur head. It is concluded that zirconia‐cutting burs are advantageous regarding durability, and carbide burs are rather ineffective against carbide substrate.     

5种不同去牙面正畸残余粘接剂方法比较

目的 通过比较5种方法去除牙面残余正畸粘接剂对牙面的影响及操作所用时间,为筛选最佳去牙面粘接树脂方法提供参考。方法 选用正畸治疗需要拔除的健康前磨牙40颗,按不同的去牙面粘接剂方法随机分为5组,每组8颗。在常规粘接托接槽并去粘接后,分别用碳化钨钻（A组）、碳化钨钻+矽粒子（B组）、金刚砂钻（C组）、金刚砂钻+矽粒子（D组）、矽粒子（E组）做牙面处理,记录各组操作时间(T),并在扫描电镜(SEM)下观察、照相,记录釉质损伤指数（enamel damage index）。采用SPSS20.0软件包对操作时间T及EDI分别进行单因素方差分析及非参数秩变换分析。结果 各组EDI排序为C组>D组>A组>B组>E组,差异具有统计学意义（P<0.05）。各组操作时间排序为E组>D组>B组>A组>C组,差异具有统计学意义（P<0.05）。结论 用高速碳化钨钻加矽粒子去除残余粘接剂对釉质损伤较小且操作时间合理,值得临床推荐。     

Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

PURPOSE

The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material.

MATERIALS AND METHODS

A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05.

RESULTS

Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001).

CONCLUSION

Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.     

Different techniques of residual composite removal following debonding--time taken and surface enamel appearance.

Four different methods of in vitro residual composite removal following debonding performed by two different operators (an orthodontist and a hygienist) were assessed for enamel surface damage (using scanning electron microscopy) and the time involved. There was no difference in the quality of enamel surface appearance between the two operators, regardless of the method used for composite removal. There was a statistically significant difference (P less than 0.05) for the time taken for composite removal between the two operators using a tungsten carbide bur method only. It is suggested that an expanded duties auxiliary with the practical skills of the hygienist would be able to remove residual composite debris and produce a satisfactory polished enamel surface using tungsten carbide burs and aluminium oxide polishing discs, thus becoming a safe and cost-effective member of the orthodontic team.     

Enamel Surface Roughness of Preferred Debonding and Polishing Protocols

Objective:: This study investigated the surface roughness of enamel after debonding and instrumentation with commonly used methods.

Methods:: Part I: a survey was sent to active members of the American Association of Orthodontists to determine popular bonding, debonding, and polishing protocols. Part II: brackets were bonded to the buccal surface of 30 extracted human premolar teeth. After debonding, residual adhesive was removed with 12-, 16-, and 20-fluted titanium carbide burs as based upon the survey results. The teeth were scanned with a surface profilometer for surface roughness. Part III: the teeth were further polished using a Reliance Renew polishing point or a prophy cup with pumice and rescanned for surface roughness.

Results:: Part I: the majority of respondents used a generic bracket-removing plier to remove fixed appliances (53%) and a high-speed handpiece for adhesive removal (85%). The most popular bur was a 12-fluted carbide bur without water spray. The majority of respondents used pumice paste and/or Reliance Renew points after adhesive removal. Part II: there was a significant difference in enamel surface roughness when 12-, 16-, and 20-fluted carbide burs were compared via surface profilometry. Part III: further polishing with a Reliance Renew point or a prophy cup and pumice did not provide a significantly smoother surface.

Conclusions:: The results show large variation in debonding and polishing techniques. Creating a smooth enamel surface is equally possible with 12- or 20-fluted carbide burs. Further polishing with pumice and prophy cup or Renew point does not provide an enamel smoother surface.     

Evaluation of Two Trephine Techniques for Removal of Fractured Rotary Nickel-titanium Instruments from Root Canals

IntroductionThe aim of this in vitro study was to evaluate the effects on root dentin of 2 trephining techniques using an ultrasonic tip or a trepan bur in the mesial canals of mandibular molars during attempts to remove fractured file fragments using micro–computed tomographic imaging.MethodsTwenty-one teeth with a similar anatomic configuration in mesial (buccal and lingual) canals were selected. A 4-mm apical segment of K3 file size 25/.06 was fractured in each mesiobuccal and mesiolingual canal 5 mm apically from the canal orifice. A staging platform was prepared at the coronal aspect of the broken instrument followed by either ultrasonics or a new trepan bur technique to expose a 1- to 1.5-mm length of the fragment. If the broken instrument could not be removed by exposing it either by ultrasound or the trepan bur, a microtube device was used to attach to and withdraw the fragment. Micro-CT scanning was performed before and after removing the broken instrument. Canal volume, diameter, and furcal root dentin thickness were measured by using image analysis software. The time required for the removal of the instrument fragments was recorded. The result was statistically analyzed using the paired t test.ResultsThe trepan bur technique had significantly less impact on canal volume, diameter, and furcal root dentin thickness change than the ultrasonic technique (P < .001). The time consumed for successful removal of the fragments was significantly less in the trepan bur group (8.9 ± 3.5 minutes) than in the ultrasonic group (25 ± 11.9 minutes) (P < .001).ConclusionsA new small-sized trepan bur technique was superior to the use of ultrasound with regard to the amount of dentin removed and the speed in the removal of fractured instruments from root canals.     

A New Carbide Finishing Bur for Bracket Debonding

BACKGROUND: The removal of residual bonding resin with rotary instruments after bracket debonding may damage the enamel surface. Conventional carbide burs may scratch the enamel due to the shape and sharpness of their blades. CARBIDE FINISHING BUR: A new carbide finishing bur with a slightly tapered shape, rounded tip and eight twisted blades has been developed. As a special feature the wedge angle of the blades has been enlarged to ca. 130-135 degrees by means of an oblique ground chamfer (relief angle ca. 0-5 degrees). The transition from head to shaft has been smoothed off with a safety chamfer. Overall, the cutting capacity has been reduced in the enamel, while the bur has remained sufficiently sharp within the adhesive resin. PROTOTYPE TESTING: For prototype testing, incisor brackets were bonded in vitro to 70 human incisors according to the standard clinical technique and removed after 7 days. Residual bonding resin was removed with conventional carbide burs and with gradually modified prototypes of the new finishing instrument respectively. The resulting enamel surfaces were evaluated by scanning electron microscopy. The specimens were then treated with a polishing paste and evaluated again. RESULTS: Conventional carbide burs remove not only residual bonding resin but also some enamel; scoring may occur. The newly developed finishing bur has been proven by morphological evaluation to be less aggressive in removing residual bonding resin after bracket debonding.     

Comparative effects of tungsten,diamond burs and laser for residual adhesive removal after orthodontic debonding on flexural strength,surface roughness and phase transformation of high-translucent zirconia: An in vitro study

ObjectivesInformation regarding the effects of orthodontic bracket debonding on zirconia restorations, and the preferred method for residual adhesive removal from the zirconia restoration surface is lacking. Thus, this study aimed to assess the effects of different methods of residual adhesive removal after orthodontic bracket debonding on flexural strength, surface roughness, and phase transformation of high-translucent (HT) zirconia.Materials and methodsThis in vitro study evaluated 72 bar-shaped HT zirconia specimens; 18 specimens were assigned to the control group. Metal brackets were bonded to the remaining specimens by resin cement. After bracket debonding, the residual adhesive on the surface of specimens was removed by three methods (n = 18): a 30-flute tungsten-carbide (TC) bur at low speed, an ultrafine diamond bur at high speed, and Er:YAG laser irradiation. The surface roughness (Ra and Rz) was measured. X-ray diffraction (XRD) analysis was carried out, and the flexural strength was measured as well. Data were statistically analyzed (α = 0.05).ResultsBefore polishing, all methods increased the Ra and Rz values (P < 0.05) except for the diamond bur yielding a Rz value comparable to that of the control group. The Ra values of the test groups were comparable after polishing, and still higher than that of the control group (P < 0.05). The flexural strength of all three test groups was comparable (P > 0.05), and significantly lower than that of the control group (P < 0.001). The monoclinic phase was not observed in any group.ConclusionsOrthodontic bracket debonding adversely affects the surface roughness and flexural strength of zirconia despite polishing.     

Effect of various grit burs on marginal integrity of resin composite restorations

The purpose of this study was to evaluate the generation of enamel cracks and gaps at the cavosurface margin of resin composite restorations using various burs. Saucer-shaped cavities with a bevel were prepared on mid-coronal buccal or lingual surfaces of extracted human molars using a regular-grit round diamond bur, a fine-grit diamond bur, a superfine-grit diamond bur or a six-bladed tungsten carbide bur with an air turbine handpiece. The enamel margin of the cavity in each group was observed by a light microscope. Cavities were restored with a self-etching adhesive and a light-cured composite resin. After thermocycling, enamel cracks and gaps at the cavosurface margins were observed and scored. Specimens were sectioned longitudinally in two halves, and the resin-cavity interface was observed by means of a light microscope. In cavity preparation, the regular-grid diamond bur and the tungsten carbide bur caused more cracks in the marginal enamel than other groups. From the surface and sectioned surface observation of restored teeth, the superfine-grit diamond bur generated fewer cracks and gaps than the other burs.     

The effect of different surface preparation techniques on the survival probabilities of orthodontic brackets bonded to nanofill composite resin

Abstract

Objective: To analyze the survival probabilities of different surface preparation techniques for bonding brackets to nanofill composite resin.

Design: In vitro, laboratory study.

Setting: Mahidol University, Bangkok, Thailand.

Materials and methods: Thirty‐five nanofill composite resin specimens/group were subjected to four surface preparation techniques as follows: (1) sandblast using aluminium oxide powder of 90?μm; (2) abrasion using diamond bur; (3) hydrofluoric acid etching for 2?min; and (4) 37% orthophosphoric acid etching for 30?s. Plastic conditioner was applied then brackets were bonded. Shear bond strength tests were carried out on a universal testing machine.

Main outcome measures: Shear bond strength (MPa) and debonding force (N) were analyzed using Weibull analysis

Results: The maximum stress and debonding force levels with a 95% probability of survival ranking from highest to lowest were: (1) sandblast group (4·2?MPa, 45·5?N); (2) diamond bur group (2·2?MPa, 25·3?N); (3) orthophosphoric group (1·9?MPa, 19·8?N); and (4) hydrofluoric group (0·8?MPa, 10·9?N). There was a significant difference in the adhesive remnant index scores between the surface preparation techniques (chi squared P<0·001).

Conclusion: Bonding orthodontic brackets to nanofill composite resin materials may result in lower bond strengths and special surface preparation techniques might be required to avoid increased numbers of bond failures. Surface treatment with sandblasting followed by plastic conditioner could increase the survival probability. The use of a diamond bur, orthophosphoric etching or hydrofluoric etching cannot be recommended.     

Comparison of Sectioning Rates Among Carbide and Diamond Burs Using Three Casting Alloys

PURPOSE: This study compared the sectioning rates of commercially available high noble, noble, and base metal casting alloys using two new cross-cut tungsten carbides specifically manufactured for alloy sectioning and two medium grit diamond burs. MATERIALS AND METHODS: Rectangular bars cast from a base metal alloy (Ni-Cr-Mo-Be), a noble alloy (Pd-Cu-Au), and a high noble alloy (Au-Ag-Cu-Pd) were sectioned under controlled conditions. Two types of cross-cut tungsten carbide and two types of medium grit diamond burs were tested using a high-speed handpiece under a coolant flow rate of 20 mL/min and an applied load at the bur tip of 0.9 N (91.5 g). Three 4-mm cuts were made through the alloy specimens using six burs of each type. The time required for Cuts 1, 2, and 3 was recorded, and sectioning rates in millimeters per minute were calculated as a relative measure of cutting efficiency. For each alloy, the total time required for the three cuts was analyzed using one-way analysis of variance (one-way ANOVA) and Scheffé tests (alpha = 0.05) to determine differences in sectioning rate among bur types. RESULTS: In general, mean sectioning rate for Cut 1 through Cut 3 decreased with longer use of the bur. Regarding total sectioning times, the carbide burs sectioned the base metal alloy significantly faster (P < .001) than the diamond burs. However, diamond burs sectioned the high noble alloy significantly faster (P < .001) than the carbide burs. Diamond burs also sectioned the noble alloy more quickly than the carbide burs, but the difference was not statistically significant. CONCLUSIONS: The cross-cut tungsten carbide burs should be used to section the base metal alloy but the medium grit diamond burs should be used to section the high noble alloy.     

Effect of different splint removal techniques on the surface roughness of human enamel: a three-dimensional optical profilometry analysis

Abstract –  Because there is no standard protocol for the removal of resin-based materials that retain semi-rigid trauma splints on teeth, iatrogenic enamel damage caused by various splint removal techniques has remained unknown. The purpose of this study was to evaluate the effect of five different resin removal techniques (H6/H7 scaler, ultrafine diamond bur, ultrasonic scaler, 16-blade tungsten carbide bur, and Sof-Lex disks) on the surface roughness of human enamel. Three-dimensional white-light interferometry, a non-contact profilometry technique, was used to obtain qualitative and quantitative measurements of surface roughness both at baseline and after finishing procedures. Statistical analysis using Friedman test and Wilcoxon signed ranks test showed that the roughest enamel surface was obtained after splint removal with the hand scaler ( P  < 0.05). Overall, the smoothest enamel surface was obtained after removal of resin with Sof-Lex disks and the 16-blade tungsten carbide bur ( P  < 0.05).