Vol 16, No 1, 2014 7

Microtensile Bond Strength to Enamel Affected by

Hypoplastic Amelogenesis Imperfecta

Batu Can Yamana / Fusun Ozerb / Cigdem Sozen Cabukustac / Meltem M. Erenc / Fatma Korayd / Markus B. Blatze

Purpose: This study compared the microtensile bond strengths ( TBS) of two different self-etching (SE) and etch-and-rinse (ER) adhesive systems to enamel affected by hypoplastic amelogenesis imperfecta (HPAI) and analyzed the enamel etching patterns created by the two adhesive systems using scanning electron microscopy (SEM).

Materials and Methods: Sixteen extracted HPAI-affected molars were used for the bond strength tests and 2 molars were examined under SEM for etching patterns. The control groups consisted of 12 healthy third molars for TBS tests and two molars for SEM. Mesial and distal surfaces of the teeth were slightly ground flat. The ad-hesive systems and composite resin were applied to the flat enamel surfaces according to the manufacturers’ instructions. The tooth slabs containing composite resin material on their mesial and distal surfaces were cut in the mesio-distal direction with a slow-speed diamond saw. The slabs were cut again to obtain square, 1-mm-thick sticks. Finally, each stick was divided into halves and placed in the TBS tester. Bond strength tests were per-formed at a speed of 0.5 mm/min. Data were analyzed with two-way ANOVA and Tukey’s tests.

Results: There was no significant difference between the bond strength values of ER and SE adhesives (p > 0.05). However, significant differences were found between HPAI and control groups (p < 0.05). HPAI-affected enamel surfaces exhibited mild intra- and inter-prismatic enamel etching patterns after orthophosphoric acid ap-plication, while conditioning of HPAI-affected enamel with SE primer created a slightly rough and grooved surface.

Conclusion: SE and ER adhesive systems provide similar bond strengths to HPAI-affected enamel surfaces.

Keywords: Amelogenesis imperfecta, bond strength, microtensile, self-etch adhesive, etch-and-rinse adhesive.J Adhes Dent 2014; 16: 7–14. Submitted for publication: 16.03.12; accepted for publication: 30.05.13doi: 10.3290/j.jad.a30554

a Assistant Professor, Department of Operative Dentistry, Faculty of Dentistry, Osmangazi University, Eskişehir, Turkey. Idea, performed experiments and statistical analysis, wrote the manuscript.

b Clinical Associate, Department of Preventive and Restorative Science, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA. De-signed the bond strength tests, interpreted the data, co-wrote manuscript.

c PhD Student, Department of Operative Dentistry, Faculty of Dentistry, Istan-bul University, Istanbul, Turkey. Contributed to application of bond strength tests.

d Professor, Department of Operative Dentistry, Faculty of Dentistry, Istanbul University, Istanbul, Turkey. Co-supervised the study, proofread manuscript.

e Professor, Department of Preventive and Restorative Science, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA. Super-vised the study, contributed to discussion, proofread manuscript.

Correspondence: Dr. Batu Can Yaman, Department of Operative Den-tistry, Faculty of Dentistry, Istanbul University, Istanbul, Turkey. Tel: +90-2124142020/30369, Fax: +90-2125250075. e-mail: batucan@istanbul.edu.tr or batucanyaman@hotmail.com

Amelogenesis imperfecta (AI) is a group of inherited disorders affecting enamel formation and are char-

acterized by clinical and genetic heterogeneity.13 The autosomal dominant forms of AI represent its most com-mon form, representing approximately 85% of inherited enamel diseases.5 The incidence of amelogenesis im-

perfecta reportedly varies between approximately 1:700 and 1:16,000, depending on the population studied and diagnostic criteria. Clinically, these developmental den-tal defects range from opacities to severe hypoplasia.20

The diverse clinical presentation of AI is thought to be the result of specific genetic defects affecting the deposi-tion, calcification, and maturation of enamel.23 Four major types were recognized based on phenotype (hypoplas-tic, hypomaturation, hypocalcified, and hypomaturation-hypoplastic) and then subdivided into 15 subtypes based primarily on phenotype and, secondarily, by mode of in-heritance.1

Enamel hypoplasia is an exclusive ectodermal distur-bance, related to alterations in the organic enamel matrix which can cause white flecks, narrow horizontal bands, lines of pits, grooves, and discoloration of the teeth vary-ing from yellow to dark brown.32 Hypoplastic enamel does not develop to normal thickness. On radiographs, enamel contrasts normally from dentin.37 Enamel hypocalcifica-tion is a defect in the mineralization process, and in this form, the enamel is soft and friable.10 Hypomaturation is an abnormal occurrence in the final stages of the min-eralization process and differs from hypocalcification in that the enamel is harder, with a mottled opaque white to yellow-brown or red-brown color.11,27

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Restoration of AI-affected teeth is important not only because of esthetic and functional needs, but also be-cause of patients’ psychological improvement.16,21 Ac-cording to the type of AI and the patient’s age, many treatments have been proposed and various strategies may be used to overcome the compromised esthetics and function. A contemporary approach is the use of direct and indirect resin composite restorations by maintaining the maximum amount of dental hard tissues in young patients with AI. The ability to achieve a strong and durable bond between the restorative material and tooth structure is of paramount importance for the clinical success of such dental restorations.31

Various types of resin bonding systems have been developed over the last decade. However, current resin bonding systems can generally be divided into two main categories in terms of simplified clinical applications. Etch-and-rinse (ER) adhesive systems include aggressive phosphoric-acid etching, while self-etching (SE) systems combine etching and priming in one procedure. Both types of resin bonding systems have the ability to produce high bond strengths to enamel and dentin.11,25

However, there is a discussion among clinicians about the preferred resin material for treatment of AI-affected teeth. In some patients with AI, bonded restorations have been successful to restore teeth to acceptable form, function, and esthetics.12,33 In others, however, adhesive restorations showed high failure rates associ-ated with inadequate bonding between the restoration and enamel.9,28,39 Chemical and morphological differ-ences between sound and AI-altered enamel accounted for these failures.10,24

The availability of AI-affected teeth for laboratory bond-strength testing is limited. In the dental literature, there are only a few studies testing the bonding ability of resin materials to AI-affected enamel.8,19,24 However, in these studies, the phenotypes of AI-affected enamel are differ-ent from those of the present study. This in vitro study compared the microtensile bond strengths of two different types of adhesive bonding systems (SE and ER) to enamel affected by HPAI. The enamel etching patterns of two bonding systems were analyzed with a scanning electron microscope (SEM).

The hypotheses tested were that: 1. The bond strength to HPAI-affected enamel exhibits

differences as compared with that to sound enamel.2. Bond strengths to HPAI-affected enamel are different

between SE and ER adhesive systems. 3. There is a difference in etching patterns between SE

and ER adhesive systems on AI-affected enamel and healthy enamel.

MATERIALS AND METHODS

Collection and Grouping of Experimental Teeth

The seven patients who were self-conscious about the appearance of their teeth were referred to the Depart-ment of Operative Dentistry for treatment. Prior to treat-ment, a detailed medical, dental, and social history

was obtained and recorded. The intraoral examination revealed that the teeth were of yellow-brown color and the thickness of the enamel was reduced. The enamel surface was smooth or smoothly irregular, and glossy. Radiographically, a contrast between enamel and dentin was observed. According to the criteria described by Witkop,37 the cases were diagnosed as hypoplastic am-elogenesis imperfecta (HPAI) type ID by two independent operators who were calibrated with a number of indi-vidual parameters specific to the disorder.

Eighteen fully or partially erupted third molars sched-uled for extraction were collected from the patients with HPAI after obtaining the patients’ informed consent. Ad-ditionally, 14 caries- and restoration-free permanent, healthy, freshly extracted human third molars were used in the study for the control groups. All teeth were cleaned and soft tissue remnants were removed; then the teeth were stored in saline solution (0.9 % sodium chloride in water) at 4ºC for one week. The roots of the teeth were then removed with a slow-speed saw (Isomet, Buehler; Lake Bluff, IL, USA) under water irrigation. Sixteen HPAI-affected enamel teeth were selected for TBS testing and the two remaining HPAI-affected molars were used for SEM analysis. As controls, twelve healthy third molars were used for the TBS test and two were selected for SEM analysis.

The mesial and distal enamel surfaces of the teeth were slightly ground with 600-grit SiC abrasive paper for 10 s to obtain flat enamel surfaces, and then rinsed and dried with an air syringe for a total of 10 s.

Experimental Design

The adhesive systems and composite resin restorations were applied to mesial and distal enamel surfaces of the teeth at random and according to the manufactur-ers’ instructions. Detailed material information is listed in Table 1.

Groups 1 (ER Adhesive Control Group) and 2 (ER Adhe-sive HPAI Affected Enamel Group): Phosphoric acid 35% (3M ESPE; St Paul, MN, USA) was applied to the ground enamel surface for 30 s and then rinsed for 15 s with wa-ter. Two consecutive coats of ER adhesive (Adper Single Bond 2, 3M ESPE) were immediately applied and gently dried for 5 s each, avoiding excess of the adhesive agent. Subsequently, the bonding surface was light cured for 10 s (LE Demetron II; Bioggio, Switzerland). Microhybrid composite resin (Filtek Supreme XT, 3M ESPE; Seefeld, Germany) was built up on the pretreated surface in two incremental layers, and each layer was light cured for 20 s. The light output of the curing unit was 950 mW/cm2.

Groups 3 (SE Adhesive Control Group) and 4 (SE Ad-hesive HPAI Affected Enamel Group): The primer of the bonding system (Clearfil SE Primer, Kuraray Medical; Kurashiki, Japan) was applied to the enamel surface for 20 s and then dried with a light flow of air. Subsequently, the bonding agent (Clearfil SE Bond, Kuraray Medical) was applied and gently dried with air flow. The bonding surface was then light cured for 10 s. The composite resins were applied in the same manner as mentioned above.

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Yaman et al

Microtensile Bond Strength Testing

The tooth slabs with composite resin material on their mesial and distal surfaces were cut in a mesio-distal direction with a slow-speed saw (Isomet 1000 Buehler), creating slabs 1 mm thick. Three sound slabs were se-lected from each tooth to equalize the number of tested slabs. Subsequently, the slabs were cut again to obtain square 1-mm-thick sticks. Each stick was divided into halves. Therefore, each cut test stick represented one of the test groups (Fig 1). Two or three sticks were ob-tained from one tooth surface for each adhesive group. The sticks were fixed to the TBS testing machine (Bisco Microtensile Tester; Schaumburg, IL, USA) with a cyanoacrylate adhesive (Zapit; Corona, CA, USA ) and tested in tension at a crosshead speed of 0.5 mm/min until fracture occurred. Since no more than 5% of all tested specimens failed during tooth sectioning, they were not included in the data analysis but shown in Table 2. A diagrammatic representation of specimen preparation is shown in Fig 1.

Table 1 Composition and manufacturers of the materials used in the study

Materials and Lot Numbers

Composition Manufacturers

Adper Single Bond 2Lot# N113791

Water, ethanol, bis-GMA, HEMA, UDMA, bisphenol-A glycerolate, polyalkenoic acid copolymer, dimethacrylate, camphorquinone, 5-nm silica particles

3M ESPE; St Paul, MN,USA

Clearfil SE BondLot# 061538

Primer: MDP, HEMA, hydrophilic dimethacrylate,camphorquinone, diethanol, toluidine, waterBond: MDP, bis-GMA, hydrophobic dimethacrylate, camphorquinone,diethanol, toluidine, silanated colloidal silica

Kuraray Medical; Kurashiki, Japan

Filtek Supreme XTLot# 20070714

Matrix: bis-GMA, bis-PMA, TEG-DMA, UDMAFiller: Silica nanofillers, zirconia/silicananocluster (0.6−1.4 μm)

3M ESPE; Seefeld, Germany

Fig 1 Diagrammatic representation of specimen preparation. a) Cutting slabs from the tooth. b) Obtaining sticks from the slabs. c) Long sticks ready to cut into two parts. d) Microten-sile test sticks. D: dentin, C: composite resin, E: enamel.

a

b

c

d

MESIAL DISTAL

MESIAL DISTAL

D

E

C

C E D D E C

Table 2 The distribution of failed sticks during cut-

ting and failure modes after microtensile bond testing

(%)

  a b c d e f

Group 1 (ER-Control)

0 60 5 25 10 2

Group 2 (ER-HPAI)

0 35.7 0 28.5 35.7 3

Group 3 (SE-Control)

0 72.5 0 15 12.5 2

Group 4 (SE-HPAI)

0 28.5 7.1 35.7 42.8 3

Failure modes: a: cohesive failure within the resin composite or resin ad-hesive; b: adhesive failure at resin/enamel interface; c: cohesive failure within dentin; d: mixed failure with a and b; e: mixed failure with b and c; f: prematurely failed sticks.

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Yaman et al

Sample Preparations for Scanning Electron Microscopy

(SEM)

The two HPAI-affected teeth and two healthy sound third molars were used for SEM analysis. The crowns of the teeth were removed with a diamond-coated separating disk under irrigation. The teeth were cut in a mesio-distal direc-tion with a slow-speed saw. The buccal and lingual sur-faces were slightly ground to obtain flat enamel surfaces with 600-grit SiC abrasive paper for 10 s, then rinsed and dried with an air/water syringe for a total of 10 s. Clearfil SE Primer was applied for 20 s to the buccal surface of HPAI-affected enamel. The lingual surface of the enamel was etched with 35% orthophosphoric acid for 30 s. All specimens were sputter coated with gold-palladium for 60 s. The surface morphology of etched HPAI-affected and healthy enamel was examined with an SEM (JSM5600, JEOL; Tokyo, Japan) at 750X and 1500X magnifications.

Failure Analysis

The mode of failure was determined at a magnification of 20X with a stereomicroscope (SZ61, Olympus; Tokyo, Japan). Failure modes were classified as: (a) cohesive

failure within the resin composite and/or resin adhe-sive; (b) adhesive failure at the resin/enamel interface; (c) cohesive failure within dentin; (d) mixed failure of (a) and (b); and (e) mixed failure of (b) and (c). Each type of failure mode was expressed as a percentage of the total number of specimens in that group.

Statistical Analysis

Numerical (quantitative) data were presented as means and standard deviation. Two-way ANOVA and Tukey’s multiple comparison tests were used to compare the means of the two adhesives. The significance level was set at p ≤ 0.05. Statistical analysis was performed with GraphPad Prism4 (GraphPad Software; La Jolla, CA, USA) for Windows.

RESULTS

The results of two-way ANOVA revealed that there were no interactions between adhesives and types of enamel (p = 0.4136). Bond strength to sound vs HPAI-affected enamel was found to differ highly significantly (p < 0.0001). The split-plot model and box plot of the micro tensile bond strength results are shown in Table 3 and Fig 2.

Mean TBS results and standard deviations for study groups are listed in Table 4 and Fig 3. Although the mean bond strength value (MPa) of the HPAI-affected enamel was higher with ER (19.63 ± 8.16) than with SE (18.21 ± 5.72), there was no statistically significant difference (p > 0.05). However, significant differences were found between HPAI-affected enamel and control group results (p < 0.05). The highest TBS was ob-tained for group 1 (31.59 ± 7.78), followed by group 3 (29.24 ± 7.17). The lowest bond strength was observed in group 4 (18.21 ± 5.72). The failure mode distribution (%) is shown in Table 2. The majorities of the fracture pat-terns were adhesive failure at the resin/enamel interface and cohesive failure within the enamel for HPAI groups; also in control groups, the most common fracture patterns were adhesive failure at the resin/enamel interface and mixed failure modes.

Table 3 Two-way ANOVA of microtensile bond

strength (split-plot model)

Source of variation

Df Sum of squares

Mean square

F

Interaction 1 17.01 17.01 0.6754

Adhesives 1 107.8 107.8 4.279

Enamel 1 2978 2978 118.2

Residual 80 2015 25.18

Fig 2 Bar graph showing means and standard deviations of of the microtensile bond strength (two-way ANOVA).

Table 4 Microtensile bond strengths of adhesive sys-

tems to the enamel affected by HPAI and control groups

Groups n Bond strengths (MPa) (mean ± SD)

Group 1 (ER-Control) 41 31.59 ± 7.78b

Group 2 (ER-HPAI) 45 19.63 ± 8.16a

Group 3 (SE-Control) 40 29.24 ± 7.17b

Group 4 (SE-HPAI) 47 18.21 ± 5.72a

Same lowercase letters indicate no significant difference (p < 0.05) within same column.

Sound HPAIEnamel

ER

SE

MP

a

35

30

25

20

15

10

5

0

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Yaman et al

SEM Findings

The morphological changes in the enamel surfaces treated with the phosphoric acid etchant or self-etching primer are shown in Figs 4 and 5.

The orthophosphoric acid applied to HPAI-affected enamel surfaces created shallow parallel grooves demar-cating the incremental growth of enamel and a very few pits with diameters similar to the diameter of the prism core (Fig 4a). On the other hand, phosphoric acid pro-duced well-defined etching patterns on the sound enamel. Different dissolutions of either the prism cores or bounda-ries could be seen across the entire enamel surface of the teeth (Fig 4b).

Unlike phosphoric acid-treated surfaces, both the HPAI-affected and sound enamel etched with SE primer showed a less distinctive pattern. Especially the primer produced a very mild etching effect on HPAI-affected enamel, with most of the surface remaining unetched. The enamel also appeared slightly rough and grooved (Fig 5a). In the case of the self-etching primer, the intact healthy enamel surface was not excessively demineral-ized, although some surface porosity was observed on the surface that was treated with the SE primer for 20 s, as seen in Fig 5b.

Fig 3 TBS results of the study (Tukey’s HSD test).

Fig 4 The SEM micrographs of enamel surfaces. a) HPAI-affected enamel after 35% orthophosphoric acid application for 30 s (750X magnification). b) HPAI-affected enamel after 35% orthophos-phoric acid application for 30 s (1500X magnification). c) Healthy, sound enamel after 35% orthophosphoric acid applica-tion for 30 s (750X magnification). d) Healthy, sound enamel after 35% or-thophosphoric acid application for 30 s (1500X magnification).

a

c

b

d

Group 1 (ER-Control) Group 2 (ER-HPAI) Group 3 (SE-Control) Group 4 (SE-HPAI)M

Pa

35

30

25

20

15

10

5

0

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DISCUSSION

There are several alternatives for the rehabilitation of defective enamel in amelogenesis imperfecta (AI) pa-tients. The ultimate treatment plan relates to the age and socioeconomic status of the patient, type and se-verity of the disorder, and the intraoral situation at the time of treatment planning.27

The mineral content of dental hard tissues is related to their potential micromechanical interlocking with bonding agents. The higher mineral content of enamel is expected to generate a better mechanical interlocking with the adhesive resin than is the case with dentin sub-strate.35 However, enamel affected by AI presents loss of the normal architecture. Enamel prisms are incom-pletely formed, sometimes with the presence of abnor-mal amorphous material obscuring the rods. Genetic mu-tations may result in hypocalcification of enamel, as the altered tissue shows incomplete biomineralization and thus lower bond strength.2,6,30 El-Sayed et al6 reported an approximately 40% mineral reduction in enamel af-fected by HPAI. However, hypoplastic defects result in deficiencies in the amount of enamel usually character-ized as “thin enamel”.6 One would expect that the differ-ences in mineral content and structure of HPAI-affected enamel may provide challenges to the bond of adhesive resin system.

Bond strength studies on AI-affected human teeth are rare due to the difficulty of collecting respective sam-ples. Sixteen teeth with HPAI were obtained for bond

strength tests in this study. Because small flat enamel areas on the specimens were obtained, the microtensile bond strength test was selected as the preferred method to evaluate bond strengths of ER and SE adhesives on HPAI-affected enamel. Advantages of microtensile bond strength tests include: (1) more adhesive and fewer cohe-sive failures; (2) higher interfacial bond strength values; (3) ability to measure regional bond strengths; (4) means and variances can be calculated for single teeth; (5) test-ing of bonds to irregular surfaces; (6) testing of very small areas.17

The two adhesive systems used for comparison in this study (Adper Single Bond 2 and Clearfil SE Bond) were selected because of their proven long-term clinical per-formance.7,36

In the present study, however, the SE system showed lower bond strength values (29.24 ± 7.17) to healthy enamel than did ER (31.59 ± 7.78), but no statistically significant difference was found between bond strength values of the two adhesive system (p > 0.05), which is in agreement with other studies which reported that self-etching adhesives were as effective as etch-and-rinse adhesives on healthy enamel surfaces.14,15,18

The penetration and diffusion of the bonding agent into the demineralized enamel surface were very important for the enamel adhesion.4 The bond strength to the phosphoric acid-etched enamel was mainly attributable to the resin’s ability to penetrate between the enamel crystallites and rods.29 This ultrastructure might have contributed to the high bond strength values obtained with the ER.

Fig 5 SEM micrographs of enamel sur-faces. a) HPAI-affected enamel after Clearfil SE Primer application for 20 s (750X magnification). b) HPAI-affected enamel after Clearfil SE Primer applica-tion for 20 s (1500X magnification). c) Healthy, sound enamel after application Clearfil SE Primer for 20 s (750X magni-fication). d) Healthy, sound enamel after application Clearfil SE Primer for 20 s (1500X magnification).

a

c

b

d

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Yaman et al

In this study, the bond strength of the adhesives to the AI-affected enamel was significantly lower than that of the healthy enamel; thus, the first hypothesis was accepted. The enamel of the normal teeth is a highly mineralized tissue containing large crystals organized in a prismatic structure. HPAI-affected enamel has morphological and micromorphological differences from the sound healthy enamel. These different results might be explained by the presence of mineralization as well as morphologi-cal changes detected at the crystallite level in the HPAI-affected teeth.38

Even though the bond strength values were slightly higher with the ER adhesive system, there was no statis-tically significant difference between ER and SE adhesives in HPAI-affected enamel groups. Therefore, the second hypothesis of our study was rejected. The slightly higher bond strength values for the ER adhesive system can be explained by more microretentive tooth surface obtained on HPAI-affected enamel with phosphoric acid than with the primer of SE adhesive.3

In a study by Faria-E-Silva et al,8 hypocalcified amelo-genesis imperfecta (HCAI) enamel bond strengths were 14.2 MPa with the ER Adper Single Bond 2 adhesive sys-tem and, therefore, lower than the values observed in this study. These differences can be attributed to the different micromorphological alteration of the enamel related to the severity of HCAI and different types of bond strength test-ing methods. Microshear and microtensile test methods usually yield different bond strength values, with micro-tensile bond strength values up to two times greater than corresponding microshear values.22,26

The primers of SE adhesive systems combine acidic monomers with a priming agent, which allows these mono-mers to penetrate to the same depth in which demineral-ization occurs. This must be considered an advantage, as microporosities created by the etching are completely penetrated by the adhesive and provide micromechanical interlocking with enamel.12 Interestingly, no other study that compared etching patterns of ER and SE adhesive systems could be found in the dental literature for HPAI. In this study, the mildly acidic primer of a SE adhesive system was used to etch HPAI-affected enamel surfaces. SEM images revealed only slight etching patterns and shallow grooves on the enamel surfaces (Fig 5). Independ-ent of the different appearance in the SEM images, bond strength values achieved with the SE adhesive were not different from the ones obtained with the ER adhesive and orthophosphoric acid. This can be attributed to the ground enamel surface and the chemical bonding performance of the SE adhesive system.34

In the SEM micrographs, orthophosphoric acid was more effective in creating a desirable etching pattern both of HPAI-affected enamel and sound enamel surfaces than the primer of the SE adhesive system (Fig 4). In the cur-rent study, 35% orthophosphoric acid was applied for 30 s to HPAI-affected enamel and sound enamel. Shallow parallel grooves as demarcation lines resulting from the rhythmic and appositional enamel production were seen in both enamel types after acid application. A typical etching pattern was created along the grooves in healthy enamel.

However, on the HPAI enamel no typical etching pattern was noticed. Only a few pits with diameters similar to the diameter of the prism core were detected. The remark-able finding was that the surface of etched HPAI-enamel appeared to be covered with a fibrous structure. In a study by Seow and Amaratunge,28 orthophosphoric-acid etching of smooth HPAI-affected enamel also showed a generally uniform fibrillar surface, without any of the classical fea-tures of etched enamel. In that study, the authors also used orthophosphoric acid for 30 s for SEM observations. Due to the different enamel etching patterns between ER and SE adhesive systems, our third hypothesis was accepted.

With regard to the mode of fracture in HPAI-affected enamel groups, the most common failure modes were adhesive failure at the resin/enamel interface and mixed failures with partly cohesive failures within the dentin and resin adhesive. A possible explanation for the partly co-hesive failure is the loss of normal architecture and thick-ness of enamel due to HPAI. The bonded enamel tissues might have chipped away more easily from the dentino-enamel junction than is the case in normal enamel, leav-ing dentin surfaces exposed.

Direct composite resin restorations are the preferred clinical choice to restore function and esthetics in patients suffering from AI. The findings of this study suggest that the clinical performance of composite resin restorations bonded to HPAI-affected enamel may not be influenced by the bonding agent selection when the choice is between SE and ER adhesives. It must be noted, however, that the enamel structure of AI-affected teeth differs among the various types of AI. Since these variations may influence the bonding ability of current adhesive resin materials, generalizations of our findings are difficult. Further stud-ies are necessary to investigate and determine the best bonding protocols for different types of AI-affected enamel before clinical recommendations can be given.

CONCLUSIONS

Within the limitations of this study, the following conclu-sions were drawn:1. The micromorphological changes and irregularities

detected on the HPAI-affected enamel surface influ-enced bond strength values of both SE and ER adhe-sive systems.

2. SE and ER adhesive systems provided similar bond strengths to HPAI-affected enamel surfaces.

REFERENCES

1. Aldred MJ, Savarirayan R, Crawford PJ. Amelogenesis imperfecta: a classification and catalogue for the 21st century. Oral Dis 2003;9: 19-23.

2. Bailleul-Forestier I, Molla M, Verloes A, Berdal A. The genetic basis of inherited anomalies of the teeth. Part 1: clinical and molecular aspects of nonsyndromic dental disorders. Eur J Med Genet 2008;51:273-291.

3. Ceballos L, Camejo DG, Victoria Fuentes M, Osorio R, Toledano M, Carvalho RM, Pashley DH. Microtensile bond strength of total-etch and self-etching adhesives to caries-affected dentin. J Dent 2003;31: 469-477.

14 The Journal of Adhesive Dentistry

Yaman et al

4. Brännström M, Noredenvall KJ. The effect of acid etching on enamel, dentin, and the inner surface of the resin restoration: a scanning elec-tron microscopic investigation. J Dent Res 1977;56:917-23.

5. Dong J, Gut TT, Simmons D, MacDougall M. Enamelin maps to human chromosome 4q21 within the autosomal dominant amelogenesis imper-fecta locus. Eur J Oral Sci 2000;108:353-358.

6. El-Sayed W, Shore RC, Parry DA, Inglehearn CF, Mighell AJ. Ultrastruc-tural analyses of deciduous teeth affected by hypocalcified amelogen-esis imperfecta from a family with a novel Y458X FAM83H nonsense mutation. Cells Tissues Organs 2010;191:235-239.

7. Ermis RB, Kam O, Celik EU, Temel UB. Clinical evaluation of a two-step etch&rinse and a two-step self-etch adhesive system in Class II restor-ations: two-year results. Oper Dent 2009;34:656-63.

8. Faria-e-Silva AL, De Moraes RR, Menezes Mde S, Capanema RR, De Moura AS, Martelli H Jr. Hardness and microshear bond strength to enamel and dentin of permanent teeth with hypocalcified amelogenesis imperfecta. Int J Paediatr Dent 2011;21:314-320.

9. Gemalmaz D, Isik F, Keles A, Küker D. Use of adhesively inserted full-ceramic restorations in the conservative treatment of amelogenesis imperfecta: a case report. J Adhes Dent 2003;5:235-242.

10. Hiraishi N, Yıu CK, King NM. Effect of acid etching time on bond strength of an etch-and-rince adhesive to primary tooth dentine affected by amelogenesis imperfecta. Int J Pediatr Dent 2008;18:224-230.

11. Kanemura N, Sano H, Tagami J. Tensile bond strength to and SEM evaluation of ground and sound enamel surfaces. J Dent 1999;27: 523-530.

12. Lopes GC, Baratieri LN, de Andrada MA, Vieira LC. Dental adhesion: present state of the art and future perspectives. Quintessence Int 2002;33:213-224.

13. Mardh CK, Backman B, Simmons D, Golovleva I, Gu TT, Holmgren G, MacDougall M, Forsman-Semb K. Human ameloblastin gene: genomic organization and mutation analysis in amelogenesis imperfecta pa-tients. Eur J Oral Sci 2001;109:8-13.

14. Moura SK, Pelizzaro A, Dal Bianco K, de Goes MF, Loguercio AD, Reis A, Grande RH. Does the acidity of self-etching primers affect bond strength and surface morphology of enamel? J Adhes Dent 2006;8: 75-83.

15. Osorio R, Monticelli F, Moreira MA, Osorio E, Toledano M. Enamel-resin bond durability of self-etch and etch & rinse adhesives. Am J Dent 2009;22:371-375.

16. Özturk N, Sarı T, Özturk B. An interdisciplinary approach for restoring function and esthetics in a patient with amelogenesis imperfecta and malocclusion: A clinical report. J Prosthet Dent 2004;92:112-115.

17. Pashley DH, Sano H, Ciucchi B, Yoshiyama M, Carvalho RM. Adhe-sion testing of dentin bonding agents: a review. Dent Mater 1995;11: 117-125.

18. Perdigão J, Geraldeli S. Bonding characteristics of self-etching ad-hesives to intact versus prepared enamel. J Esthet Restor Dent 2003;15:32-41.

19. Pugach MK, Ozer F, Li Y, Sheth K, Beasley R, Resnick A, Danesh-mehr L, Kulkarni AB, Bartlett JD, Gibson CW, Lindemeyer RG. The use of mouse models to investigate shear bond strength in amelogenesis imperfecta. J Dent Res. 2011;90:1352-1357.

20. Robinson FG, Haubenreich JE. Oral rehabilitation of a young adult with hypoplastic amelogenesis imperfecta: A clinical report. J Prosthet Dent 2006;95:10-13.

21. Sabatini S, Guzman-Armstrong S. A conservative treatment for am-elogenesis imperfecta with direct resin composite restorations: a case report. J Esthet Restor Dent 2009;21:161-169.

22. Salz U, Bock T. Testing adhesion of direct restoratives to dental hard tissues. J Adhes Dent 2010;12:343-371.

23. Sanchez-Quevedo MC, Ceballos G, Garcıa JM, Luna JD, Rodriguez IA, Campos A. Dentine structure and mineralization in hypocalcified amelo-genesis imperfecta: a quantitative X-ray histochemical study. Oral Dis 2004;10:94–98.

24. Saroglu I, Aras S, Oztas D. Effect of deproteinization on composite bond strength in hypocalcified amelogenesis imperfecta. Oral Dis 2006;12:305-308.

25. Sarr M, Kane AW, Vreven J, Mine A, Van Landuyt KL, Peumans M, Lam-brechts P, Van Meerbeek B, De Munck J. Microtensile bond strength and interfacial characterization of 11 contemporary adhesives bonded to bur-cut dentin. Oper Dent 2010;35:94-104.

26. Scherrer SS, Cesar PF, Swain MV. Direct comparison of the bond strength results of the different test methods: a critical literature re-view. Dent Mater 2010;26:78-93.

27. Sengun A, Ozer F. Restoring function and esthetic in a patient with amelogenesis imperfecta: a case report. Quintessence Int 2002;33: 199-204.

28. Seow WK, Amaratunge A. The effects of acid-etching on enamel from different clinical variants of amelogenesis imperfecta: an SEM study. Pediatr Dent 1998;20:38-42.

29. Shinchi MJ, Soma K, Nakabayashi N. The effect of phosphoric acid con-centration on resin tag length and bond strength of a photo-cured resin to acid-etched enamel. Dent Mater 2000;16:324-329.

30. Sholapurkar AA, Joseph RM, Varghese JM, Neelagiri K, Acharya SR, Hegde V, Pai KM, Bhat M. Clinical diagnosis and oral rehabilitation of a patient with amelogenesis imperfecta: a case report. J Contemp Dent Pract 2008;9:92-98.

31. Silva NR, Calamia CS, Harsono M, Carvalho RM, Pegoraro LF, Fer-nandes CA, Vieira AC, Thompson VP. Bond angle effects on micro-tensile bonds: laboratory and FEA comparison. Dent Mater 2006; 22:314-324.

32. Soares CJ, Fonseca RB, Martins LR, Giannini M. Esthetic rehabilitation of anterior teeth affected by enamel hypoplasia: a case report. J Esthet Restor Dent 2001;14:340-348.

33. Turkun LS. Conservative restoration with resin composites of a case of amelogenesis imperfecta. Int Dent J 2005;55:38-41.

34. Van Meerbeek B, De Munck J, Yoshida Y, Inoue S, Vargas M, Vijay P, Van Landuyt K, Lambrechts P, Vanherle G. Buonocore memorial lecture. Adhesion to enamel and dentin: current status and future challenges. Oper Dent 2003;28:215-235.

35. Van Meerbeek B, Yoshihara K, Yoshida Y, Mine A, De Munck J, Van Landuyt KL. State of the art of self-etch adhesives. Dent Mater 2011; 27:17-28.

36. Walter R, Swift EJ Jr, Nagaoka H, Chung Y, Bartholomew W, Bras-well KM, Pereira PN. Two-year bond strengths of “all-in-one” adhesives to dentine. J Dent 2012;40:549-555.

37. Witkop CJ Jr. Amelogenesis imperfecta, dentinogenesis imperfecta and dentin dysplasia revisited: problems in classification. J Oral Pathol 1989;17:547-553.

38. Wright JT, Robinson C, Shore R. Characterization of the enamel ultra-structure and mineral content in hypoplastic amelogenesis imperfecta. Oral Surg Oral Med Oral Pathol 1991;72:594-601.

39. Yip HK, Smales RJ. Oral rehabilitation of young adults with amelogen-esis imperfecta. Int J Prosthodont 2003;16:345-349.

Clinical relevance: Self-etching and etch-and-rinse adhesive systems provide reliable bonding to enamel affected by hypoplastic amelogenesis imperfecta.

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