SEM study of a self-etching primer adhesive system used for dentin bonding in primary and permanent teeth

PURPOSE: The purpose of this study was to evaluate the interfacial micromorphology of direct esthetic restorations bonded to primary or permanent tooth dentin with a self-etching primer adhesive system. METHODS: Superficial dentin at the occlusal surface of 15 primary and 15 permanent molars was exposed with a carbide bur. Prompt-L-Pop was applied in one half of each surface. A control bonding system, Single Bond or Vitremer Primer, was used in the other half Teeth were restored either with a composite resin (Filtek Z250), a compomer (Hytac), or a resin-modified glass ionomer (Vitremer). Twenty-five scanning electron microscope fields from 5 teeth were evaluated blindly by two investigators for each condition. RESULTS: In this study, a significant difference in quality of the interfacial seal was not observed when restorations performed in primary teeth were compared to restorations in permanent teeth. Interfacial gaps were observed in most restorations bonded with Prompt-L-Pop and restored with Filtek Z250 (9/10), Hytac (9/10), or Vitremer (5/10). No interfacial gaps were observed in teeth bonded with Single Bond and restored with Filtek Z250 (0/10) or Hytac (0/10), while all teeth bonded with Vitremer Primer and restored with Vitremer presented gaps (10/10). To understand the reason for the interfacial gaps observed with Prompt-L-Pop, we examined if this system generated a hybrid layer at the dentin/restorative material interface. All surfaces bonded with Single Bond and restored with Filtek Z250 or Hytac presented a visible hybrid layer. In contrast, 0/10 (Z250) and only 3/10 (Hytac) restorations bonded with Prompt-L-Pop showed signs of a hybrid layer. CONCLUSION: The self-etching primer adhesive system Prompt-L-Pop failed to generate sealed interfaces consistently between the dentin of primary and permanent teeth and the composite resin or the compomer evaluated in this study.     

复合树脂联合两种酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度比较

目的:比较复合树脂联合全酸蚀和自酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度。方法:收集新鲜拔除的滞留乳磨牙48个,随机分为4组,分别制备全酸蚀和自酸蚀粘结剂的釉质和牙本质试件,电子万能试验机测定各组剪切强度;体视显微镜下观察试件断面的破坏模式;扫描电镜观察粘结界面情况。结果:全酸蚀粘结剂组的釉质剪切强度明显高于牙本质剪切强度(P<0.05);自酸蚀粘结剂组釉质与牙本质剪切粘结强度无统计学差异(P>0.05);全酸蚀粘结剂组的釉质、牙本质剪切粘结强度均明显高于自酸蚀粘结剂组(P<0.05);体视显微镜及扫描电镜观察均显示,全酸蚀粘结剂与釉质和牙本质的粘结界面结合程度好于自酸蚀粘结剂。结论:全酸蚀粘结剂处理对乳牙釉质及牙本质的剪切粘结强度高于自酸蚀粘结剂。     

SEM evaluation of resin-carious dentin interfaces formed by two dentin adhesive systems.

OBJECTIVES: We investigated the influence of dentin tubule direction and identifiable zone of carious dentin on the microstructure and the thickness of the hybrid-like layer (HL) formed by self-etch and etch-rinse adhesive systems. METHODS: An etch-rinse and a self-etching adhesive were bonded to dentin carious zones divided into groups with parallel or perpendicular orientation relative to the dentin tubules at the resin-carious dentin interface (N=5/variable). Bonds were prepared to each of the four zones of carious dentin apparent after staining with Caries Detector: pink, light pink, transparent and apparently normal; six non-carious third molars were controls. The microstructure and thickness of the HL were determined by SEM and compared using three-way ANOVA and Tukey's multiple comparisons (p<0.05). RESULTS: Etch-rinse controls gave thicker HLs than self-etching systems; orientation did not affect thickness for the self-etch system. Perpendicular orientations gave thicker HLs than parallel for the pink zone bonded with the etch-rinse system. For both adhesives, HL thickness in the pink zone was significantly greater than in light pink for the perpendicular group, but no significant differences were found among other variables. HL microstructure was more granular and rougher for the etch-rinse than for the self-etching system. Pores and cracks were obvious in the more demineralized zones. Resin tags were shorter and irregular in the transparent zone and often were completely absent in the outer demineralized zones (pink, light pink). SIGNIFICANCE: Microstructure of bonded interfaces varies markedly depending on adhesive system, tubule orientation and carious zone.     

Factors affecting in vitro bond strength of bonding agents to human dentin

Four generations of total-etch (fourth, fifth) and self-etching (sixth, seventh) bonding agents for use with resin composites are commercially available in the United States. Innovations in bonding agents include: filled systems, release of fluoride and other agents, unit dose, self-cured catalyst, option of etching with either phosphoric acid or self-etching primer, and pH indicators. Factors that can affect in vitro bond strength to human dentin include substrate (superficial dentin, deep dentin; permanent versus primary teeth; artificial carious dentin), phosphoric acid versus acidic primers, preparation by air abrasion and laser, moisture, contaminants, desensitizing agents, astringents, and self-cured restorative materials. This article reviews studies conducted at the Houston Biomaterials Research Center from 1993 to 2003. Results show that in vitro bond strengths can be reduced by more than 50% when bonding conditions are not ideal.     

粘结性树脂根充材料根管封闭质量的扫描电镜观察

目的：扫描电镜下观察粘结树脂等根充材料与根管牙本质壁界面的超微结构，为临床选择理想的根充材料提供理论依据。方法：18颗离体单根管前牙或前磨牙自釉牙骨质界截断，采用逐步深入技术根管预备后分为S1、S2、S3三个实验组（每组6颗牙），分别采用改良氧化锌丁香油糊剂（Cortisom01）、环氧树脂类糊剂（AH-plus）和粘结性树脂根管充填材料（Resilon—Epiphany）3种不同的根管充填材料通过热牙胶充填方式充填根管。每组3颗牙齿从距根冠面1mm处用单面金钢砂片横向片切牙根，另外3颗牙齿沿牙体长轴自根管口中心纵向切开牙根。所有标本均干燥，真空喷涂金膜，然后用扫描电子显微镜观察。结果：扫描镜图片提示粘结性树脂根管充填材料与根管牙本质壁之间完全紧密结合，树脂充填材料与根管牙本质壁紧密连接形成无缝的均一整体，但部分区域仍存在微小缝隙；环氧树脂类糊剂组充填材料与牙本质壁之间仍然存在微缝隙；而氧化锌丁香油糊荆组与根管牙本质壁存在明显的缝隙。结论：粘结性树脂根管充填材料冠方封闭质量优于氧化锌丁香油糊剂和环氧树脂类糊剂。     

Penetration of radiocalcium at the margins of resin and glass ionomer dentine bonding agents in primary and permanent teeth

OBJECTIVES: The purpose of this study was to compare the leakage of three resin dentine bonding agents (Prime and Bond, Scotchbond Multi-Purpose, Probond) and a glass ionomer dentine bonding agent (GC Fujibond LC), in cervical cavities prepared in primary and permanent molar teeth restored with a hybrid composite resin (Tetric). METHODS: Cervical cavities without a bevel at the cavo-surface margins were prepared in the buccal and lingual surfaces of extracted primary and permanent molar teeth. After being restored, the teeth were stored for 1 week in a saline solution at 37 degrees C and then thermally cycled between 5 and 55 degrees C. Marginal leakage was determined subsequently using a radioactive isotope containing 45Ca and an autoradiographic technique. RESULTS: The results revealed that there were no statistically significant differences in microleakage of the bond between permanent and primary teeth dentine and Fuji Bond LC and Probond dentine bonding agents. The difference between permanent and primary teeth groups for gingival values of the Prime and Bond 2.1 group U=22.5, p=0.0355 and the Scotchbond Multipurpose group U=24.0, p=0.0406 were statistically significant. There were no significant differences between the occlusal and gingival microleakage values in either primary or permanent teeth with Prime and Bond 2.1, Fuji Bond LC and Probond except the difference at Scotchbond Multipurpose in primary teeth. For primary teeth gingival margins, none of the bonding systems were significantly different from the control group. CONCLUSIONS: These results indicate that although no statistically significant differences were found between test and control group values, the use of Fuji II LC in cervical cavities with cementum margins in primary teeth would provide the best resistance to microleakage among the test materials while the use of Scotchbond Multi-Purpose would provide the best resistance to microleakage in cervical cavities with cementum margins in permanent teeth.     

Effect of water on bonding of one-bottle self-etching adhesives

This study evaluated the effect of water on dentin substrate bonding of one-bottle self-etching adhesives. Dentin substrates were divided into two groups: wet and dry dentin. Wet dentin is the normal substrate for bond testing whereas dry dentin was dehydrated in a desiccator for 24 hours. Bonded dehydrated teeth were then divided into two subgroups: stored in water or in desiccator for 24 hours. Microtensile bond strength of resin to dentin was measured using three one-bottle self-etching adhesives. In addition, nanoleakage evaluation was performed through the analyses of SEM and TEM micrographs. The bond strength of dry-dentin group was significantly greater than that of wet-dentin. Further, the amount of nanoleakage within the adhesive interface of dry-dentin group was less than that of wet-dentin. Results showed that bond strength and nanoleakage formation depended on the bonding substrate (wet versus dry dentin) before bonding. One-bottle self-etching adhesives might suck the water from dentinal tubules during bonding by osmosis, leading to nanoleakage formation and thus a decline in bond strength.     

An in vivo evaluation of bonding ability of comprehensive antibacterial adhesive system incorporating MDPB.

OBJECTIVES: This study examined the in vivo bonding ability to sound dentin of antibacterial adhesive systems incorporating an antibacterial monomer MDPB based on morphological evaluation of the resin-dentin interface. METHODS: Class V cavities were prepared on the buccal surfaces of the teeth of a beagle dog and a composite filling performed using (1) commercial self-etching system Liner Bond 2 (LB primer+LB bond), (2) experimental primer containing 5% MDPB and LB bond, (3) LB primer and experimental bonding-resin containing 2.5% MDPB, or (4) combination of experimental primer and bonding-resin. After 7 days, the tooth crown was cut and fixed in half-Karnovsky's solution, and the sectioned surface observed under scanning electron microscopy (SEM) after treatment with phosphoric acid and NaOCl. The ultrastructure of the bonding interface was also examined by transmission electron microscopy (TEM). Microtensile bond strengths (microTBS) of each group were measured using extracted teeth. RESULTS: SEM demonstrated that all groups produced a 1-2microm thick hybrid layer with funnel shaped resin tags, although the length of tags was shorter for the group in which MDPB-containing bonding-resin was used. TEM examination supported good adhesion of the comprehensive adhesive system employing MDPB-containing primer/bonding-resin, showing integrity between resin and dentin. There were no significant differences in microTBS among the four groups tested (p>0.05, ANOVA). SIGNIFICANCE: This study confirmed that the experimental antibacterial adhesive systems employing MDPB-containing primer or/and bonding-resin could produce an effective bond under in vivo conditions.     

Microtensile bond strength of a total-etching versus self-etching adhesive to caries-affected and intact dentin in primary teeth

BACKGROUND: The objec tives of this study were to determine microtensile bond strengths of two dentin adhesives and to compare the micromorphological structure of the resin/dentin interface in caries-affected dentin with that of intact dentin. METHODS: The authors randomly divided 40 proximal dentinal carious primary teeth and 40 noncarious anterior primary teeth into two groups (self-etching and total-etching). They used a caries-detecting dye as an indicator of the need to remove the outer carious dentin. The authors restored the teeth with a hybrid resin-based composite. After 24 hours' storage in 37 C water, specimens were sectioned and shaped to form a curved section with a cross-sectional area of 1 square millimeter, then tension was applied until they fractured. The authors prepared the resin/dentin interfaces for the two bonding systems and examined them in 10 occlusal carious and 10 noncarious teeth. STATISTICAL ANALYSIS: The bond strengths for intact and caries-affected dentin within the same group were analyzed via a t test. The authors compared the remaining dentin thickness (RDT) and dentin hardness using analysis of variance and the least significant difference test at the .05 level of significance. RESULTS: The self-etching adhesive demonstrated no statistical difference in bond strength between intact and caries-affected dentin. However, the total-etching adhesive demonstrated different bond strengths for intact and caries-affected dentin. Moreover, the RDT of specimens with intact and caries-affected dentin was not significantly different, whereas the dentin hardness of caries-affected dentin was significantly lower than that of intact dentin. The authors found a thicker hybrid layer in intact and caries-affected dentin of specimens in the total-etching group. CONCLUSION: The adhesives exhibited significantly different bond strengths in intact dentin of primary teeth. However, they exhibited similar bond strengths in caries-affected dentin.     

Self-etching primer vs phosphoric acid: an alternative concept for composite-to-enamel bonding.

The purpose of this in vitro study was (1) to investigate the composite-to-enamel bond strength and (2) to analyze the marginal adaptation of resin composite restorations in class 2 cavities using three self-etching priming agents in comparison to conventional phosphoric acid etching and bonding application. In the first part of the study 24 extracted bovine incisors were embedded in acrylic resin and ground flat with 800-grit paper. The following three self-etching priming agents/composite resins were applied to the enamel surfaces of six teeth each: Clearfil Liner Bond 2/Clearfil AP-X (Group I), Etch & Prime 3.0/Degufill mineral (Group II), Resulcin AquaPrime + MonoBond/Ecusit (Group III). In Group IV Ecusit-Mono/Ecusit was used after enamel etching with phosphoric acid (37%). Shear bond strength values measured on a T22 K testing machine at a crosshead speed of 1 mm/min were: 24.2 +/- 3.0 MPa (Group I), 21.9 +/- 1.4 MPa (II), 34.0 +/- 3.6 MPa (III), and 26.3 +/- 1.8 MPa (IV). ANOVA revealed significant (P < 0.05) differences in shear bond strength between groups, except comparison of Group I and II, and Group I and IV. In the second part of the study 24 standardized class 2 cavity preparations with the approximal box extending 1 mm above the CEJ were prepared in extracted human molars. Enamel margins were beveled and the teeth were divided into four groups of six teeth each. Cavities were restored using the self-etching priming agents Clearfil Liner Bond 2 (Group I), Etch & Prime 3.0 (Group II), and Resulcin AquaPrime + MonoBond (Group III). In Group IV composite resin restorations were placed after 37% phosphoric acid etching and bonding application (Ecusit-Mono). Quantitative SEM analysis of the marginal adaptation of the restorations after thermocycling (5-55 degrees C, 2500 cycles) and mechanical loading (100 N, 500,000 cycles) revealed excellent, gap-free margins in 91.2% (Group I), 93.0% (Group II), 92.0% (Group III), and 92.5% (Group IV) of the restorations' approximal area. There were no statistically significant differences between the four groups (P < 0.05). In conclusion, results of the present in vitro study indicate that use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in composite-to-enamel bonding restorative techniques.     

Dentin-polymer bond in resin fillings tested in vitro by thermo- and load-cycling

The effect of stress applied by thermo- and load-cycling to the bond between composite- and bonding-agent-treated dentin was tested. Cylindrical cavities in extracted human teeth, approximately one-half of the margins in dentin, were etched and treated with two bonding agents - Gluma and Clearfil Bond - before being filled with Silux composite. Forty specimens, some provided with cavity floor lining, were cycled several hundred times between 15 degrees and 50 degrees C, either immediately after light-curing or upon 24 hr of water storage. In all cases, microscopic inspection revealed unchanged adaptation at the dentin margins. Teeth with Class 3 and Class 5 cavities, ten of each and with the gingival margins entirely in dentin, were pre-treated and filled as above. The teeth were covered with a dye during loading and unloading in a manner simulating biting and chewing. Inspection of the cavity margins revealed absence of percolation at the dentin margins. It is concluded that effective bonding agents are necessary to prevent contraction gaps in resin-filled cavities where the margins are partly or entirely located in dentin.     

Microtensile bond strength of total-etch and self-etch adhesives to the enamel walls of Class V cavities

PURPOSE: To determine the difference in microtensile bond strengths (MTBS) of resin-based composite bonded to the enamel of cavity preparations using a conventional or a self-etching adhesive. METHODS: Buccal and lingual Class V cavities were prepared in each of 12 caries-free human molars. Six teeth were randomly selected to be restored with Spectrum TPH resin-based composite and Prime & Bond NT adhesive. The remaining six teeth were restored with the same composite and Prompt L-Pop self-etching adhesive. Enamel/composite sticks were cut from each specimen and subjected to microtensile bond testing. Each debonded specimen was evaluated by SEM to determine the mode of failure. RESULTS: The mean MTBS for Prime & Bond NT specimens was 15.2+/-13.1 MPa. The mean MTBS for Prompt L-Pop self-etching adhesive samples was 18.2+/-14.3 MPa. ANOVA demonstrated no statistically significant difference between the mean MTBS associated with the two adhesives (P> 0.05). The results of SEM analysis revealed that the bonding failures occurred primarily at the interface between the adhesive and the enamel, suggesting a primarily adhesive failure.     

新型自固化树脂充填Ⅴ类洞的表面边缘和内部界面适合性初探

目的探讨新型自固化树脂充填Ⅴ类洞后充填体的表面边缘和内部界面适合性。方法选用因正畸需要拔除的无龋人上颌前磨牙56颗(首都医科大学口腔医学院口腔颌面外科提供),制备Ⅴ类洞,分为2组(每组28颗)。实验组用预处理剂(Tooth primer)和新型自固化树脂(Bondfill SB)充填,对照组用自酸蚀粘接剂(Scotchbond Universal)和光固化复合树脂(Z100)充填。充填后样本牙进行疲劳实验:机械循环加载(49 N、1 Hz频率120万次)和冷热循环加载(5和55℃的水中分别浸泡1 min,共3000次),模拟口腔环境的咀嚼负荷和温度变化。疲劳实验前后样本牙浸入50%氨化硝酸银溶液并还原银离子。用扫描电镜检测分析充填体表面完整边缘百分率和内部界面银沉淀物长度。用透射电镜观察牙本质界面超微结构。结果扫描电镜显示,疲劳实验前实验组牙本质表面边缘间隙较对照组小。疲劳实验前对照组牙釉质界面银沉淀物长度[(0.67±0.15)μm]显著小于实验组[(33.54±10.27)μm](P<0.05)。疲劳实验后对照组牙釉质表面完整边缘百分率[(55.08±15.20)%]显著大于实验组[(25.15±12.47)%](P<0.05)。疲劳实验后实验组充填体表面和内部更易观察到内聚破坏。透射电镜显示,疲劳实验前对照组牙本质界面比实验组有更多的银沉淀物;疲劳实验后对照组牙本质界面破坏主要发生于混合层下方;实验组牙本质界面破坏主要发生于混合层下方和充填体内部。结论充填Ⅴ类洞时本项研究所用光固化复合树脂在牙釉质界面有较好的表面边缘和内部界面适合性,而新型自固化复合树脂在牙本质界面有良好的表面边缘和内部界面适合性。     

Efficacy of dentin adhesives in primary and permanent teeth

The purpose of the present study was to investigate the efficacy of dentin adhesives and to examine acid resistance in primary and permanent teeth. The efficacy of dentin adhesives was evaluated by SEM observation and by measuring the wall-to-wall polymerization contraction gap and dentin hardness before and after conditioning. The detailed mechanism of dentin bonding was the same in both primary and permanent teeth.     

HEMA diffusion from dentin bonding agents in young and old primary molars in vitro.

OBJECTIVE: The objective of this study was to evaluate and compare amounts of HEMA diffusion from three dentin bonding systems in young and old primary molars at a remaining dentin thickness (RDT) of 1 mm. METHODS: Occlusal cavities were prepared with RDT of 1 mm in young and old primary molars. Chambers that contain 1 ml of distilled water were attached to each tooth. The groups were treated with Total Etch+Syntac Single Component, Syntac Single Component and Clearfil SE Bond. Water eluates were analyzed by HPLC at 4 min, 24 h and 72 h. RESULTS: The cumulative HEMA release amounts were significantly different among all groups (p<0.05). Acid-etching significantly increased pulpward diffusion of HEMA and young primary teeth presented higher dentin permeability. SIGNIFICANCE: Acid-etching significantly increases pulpward release of HEMA from dentin bonding systems in primary molar teeth. Young primary molars have higher dentin permeability; so the pulp should be protected with cavity liners in deep cavities. However, the dentin bonding systems can be considered safe for clinical use in primary teeth, even in deep cavities, since the released HEMA amounts are below the level of cytotoxicity.     

Influence of dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and three dentin regions within a post space

STATEMENT OF PROBLEM: Debonding is the most frequent failure encountered with translucent fiber posts and usually occurs along the post space dentin-adhesive interface. PURPOSE: The purpose of this study was to evaluate the effect of different dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and root dentin in different regions of the post space. MATERIAL AND METHODS: Forty maxillary canines with similar root lengths were selected, sectioned at the cemento-enamel junction, and the roots were endodontically treated. Following post space preparation, the roots were divided into 4 groups of 10 specimens each, and the post spaces were treated with 1 of 4 different dentin bonding agents: light-polymerized, single-bottle bonding agent Excite (Group EX); dual-polymerized, single-bottle bonding agent Excite DSC (Group EX-DSC); self-etching primer Clearfil Liner Bond 2V with a light-polymerized bonding agent, Bond A (Group CL-LC); or self-etching primer Clearfil Liner Bond 2V with a dual-polymerized bonding agent, Bond A+B (Group CL-DC). Translucent fiber posts (D.T. Light-Post), 2.2 mm in diameter, were luted (Panavia F) in each specimen after respective dentin bonding procedures. The roots were cut into 3-mm-thick sections, perpendicular to the long-axis in cervical, middle, and apical post space dentin. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and bond strength values (MPa) were calculated by dividing the force at which bond failure occurred by the bonded area of the post. The data were analyzed with 1- and 2-way analysis of variance and Tukey multiple comparison tests (alpha=.05). Dentin adhesive bonding mechanisms in different regions of the post spaces were evaluated with a scanning electron microscope. RESULTS: The highest mean bond strength values were obtained for Group CL-LC (18.3 +/- 4.1 MPa). The dual-polymerized bonding agent resulted in significantly lower bond strength (P<.001) in combination with self-etching primer (Group CL-DC) (13.2 +/- 2.5 MPa). The light-polymerized and dual-polymerized single-bottle bonding agents provided similar bond strengths (12.7 +/- 5.0 for EX; 13.5 +/- 5.3 for EX-DSC). The regional bond strength values of single-bottle bonding agents were reduced significantly in apical post space dentin (P<.001). Self-etching primers did not demonstrate regional differences in post space dentin bonding and dense resin tags were apparent. CONCLUSION: Data suggests that the self-etching primer system used in this study was unaffected by the morphological variations in the post space dentin compared to the single-bottle bonding agents. Dual polymerization did not improve the bond strength values of the bonding agents tested.     

Technique sensitivity of dentin bonding: effect of application mistakes on bond strength and marginal adaptation

This in vitro study evaluated dentin bond strength and marginal adaptation of direct resin composites according to the manufacturers' instructions and with simulated application errors. One hundred and forty cavities were prepared into disks of freshly extracted human third molars and filled with one resin composite. Dentin adhesives of the third (with self-etching primer: Syntac Classic), fourth (with total etching: Scotchbond Multi-Purpose Plus) and fifth generation (one-bottle adhesive: Prime&Bond 2.1) were used for bonding. Simulated application mistakes were as follows: 1) prolonged etching; 2) excessive drying after conditioning; 3) drying primers immediately after application and 4) drying primers excessively. After 21 days of storage and 24 hours thermocycling (1150 cycles), replicas were made and push-out testing was performed. Replicas were examined for marginal adaptation using SEM (X200 magnification). Compared with values of the control groups, application errors resulted in dramatically decreased bond strengths and reduced percentages of gap-free margins for all products tested (p < 0.05). Excessive drying after conditioning exhibited significantly less effect for the third generation adhesive than for products requiring total etching/wet bonding.     

Leistungsvermögen unterschiedlicher Adhäsive im Milchgebiss

Background

In the post-amalgam era, adhesive measures are clinical routine in pediatric dentistry; however, it is not automatically effective to transfer bonding knowledge from permanent to deciduous teeth because the micromorphological issues are completely different.

Methods

In addition to a review of the current literature, this paper presents the results of own investigations on bonding to primary tooth enamel and dentin in milk teeth and the marginal quality which can be achieved.

Results

Important conclusions are: bonding to deciduous enamel is possible after removal of the outer prismless layer, with phosphoric acid being the predominant and most reliable method. Deciduous tooth dentin is less mineralized and therefore as a rule easy to pretreat and bond with self-etching adhesives. Phosphoric acid etching of primary dentin is not recommended. Multistep adhesives show fewer advantages in milk teeth than in the permanent dentition. Altogether, self-etching adhesives exhibit several handling advantages which make them the treatment option of choice in children. Selective phosphoric acid etching can be recommended especially in anterior restorations but in posterior teeth only in the occlusal cavity segment.     

Evaluation of shear bond strength and interfacial micromorphology of direct restorations in primary and permanent teeth--an in vitro study

This in vitro study sought to evaluate the bond strength and interfacial morphology of composite restorations in primary and permanent teeth that utilized different adhesive systems. In this study, 180 samples (n = 15 per subgroup) were submitted to shear bond strength tests while 72 samples were analyzed with scanning electron microscopy (n = 6 per subgroup). Fifty-four blocks of permanent enamel, 54 blocks of permanent dentin, 54 blocks of primary enamel, and 54 blocks of primary dentin were randomly assigned to three groups for bonding. All of the blocks received a resin composite restoration made with a matrix after the application of the dental bonding systems, according to the manufacturer's instructions. The shear bond strength test found no statistical differences among the tissues or the adhesive systems used. However, a difference in quality of the interfacial seal was observed when Single Bond restorations were compared to restorations bonded with AdheSE and Prompt-L-Pop. The Single Bond system formed an authentic hybrid layer that can ensure adequate adhesion. The other adhesive systems showed an interface with inadequate sealing and even with no sealing. The self-etching systems must be used with caution in composite restorations because the quality of the hybrid layer formed is as important as the bond strength when determining the efficacy of the adhesive.     

A comparative study of the effects of dentinal bonding agents and application techniques on marginal gaps in Class V cavities

The effectiveness of eight dentinal bonding agents (DBA's) and four of their combinations in eliminating marginal gaps in class V cavities was evaluated by the bulk method of composite application and two different incrementation techniques. The cavities were prepared one-half in enamel and one-half in dentin. Basic fuchsin 0.5% in propylene glycol was used for detection of the presence of gaps. For each cavity, the presence of gaps was scored as 0 or 1, at five enamel and five dentin locations. Marginal gaps were present in 6% of all enamel locations and in 75% of all dentin locations investigated. The gap frequency was lowest at the enamel occlusal locations, it increased gradually toward the dentin, and attained the highest value at the gingival locations. In enamel, the occurrence of gaps was dependent on the DBA's but independent of the particular technique used. In dentin, there was significant difference in gap occurrence between DBA's with any of the incrementation techniques. The frequency of gap occurrence was not significantly changed by the incrementation techniques. The most effective single agent in producing gap-free restorations was the Gluma, and the most effective combination was the Gluma/Clearfil.