available at www.jstage.jst.go.jp/browse/islsm
ORIGINAL ARTICLES
Microleakage in Class V Composite Restorations after Desensitizing Surface Treatment with Er:YAG and CO2 Lasers Hamid Reza Mozaffari 1, Alireza Ehteshami 2, Farshad Zallaghi 2, Nasim Chiniforush 3, Zohreh Moradi 4
1: Oral Medicine Department, School of Dentistry, Kermanshah University of Medical Sciences 2: Dentist, Private Practice 3: Laser Research Center of Dentistry, Tehran University of Medical Sciences 4: Operative Department, School of Dentistry, Tehran University of Medical Sciences
Aims: Glutaraldehyde, CO2 and Er:YAG lasers can be used for treatment of dentin hypersensitivity. However, their application may have adverse effects on the clinical service of restorations. This study aimed to assess the microleakage in composite restorations following surface treatment with Glutaraldehyde desensitizer, CO2 and Er:YAG laser irradiation for treatment of dentin hypersensitivity. Materials and methods: This experimental study was conducted on 60 extracted sound human teeth. Class V cavities were prepared measuring 3×3 mm using a diamond bur. Specimens were randomly divided into 4 groups of 15. Group one:no surface treatment, Group two:applying Glutaraldehyde desensitizer, Groups of three and four were irradiated with CO2 and Er:YAG lasers, respectively. Surfaces were restored with bonding agent(Single Bond 2, 3M, USA) and Z250 composite (3M,USA). Specimens were thermocycled and immersed in 1% methylene blue solution for 24 hours. Microleakage scores were assessed under a stereomicroscope at ×20 magnification. Data were analyzed using SPSS and the Kruskal Wallis test (P=0.05). Results: There was no significant difference between microleakage of groups in enamel margins (P=0.694). The difference in microleakage at the dentin margin was significant between groups (P=0.018). Conclusions: Application of Glutaraldehyde-desensitizer and CO2 laser irradiation of surfaces prior to composite restoration do not increase microleakage at the enamel or dentin margins but tooth surface treatment with Er:YAG laser significantly increased the microleakage at the dentin margins. Key words: Dentin hypersensitivity • CO2 laser • Er:YAG laser • Glutaraldehyde desensitizer Microleakage
Introduction Dentin hypersensitivity is the most common patient complaints and is defined as pain and discomfort in response to cold, hot, chemical and osmotic stimuli due to exposed cervical dentin 1, 2). The prevalence of dentin hypersensitivity ranges from 3.8 to 57% 3, 4). To Addressee for Correspondence: Zohreh Moradi Iran,Tehran,North Amirabad Ave, Dental Faculty of Tehran University of Medical Sciences Tel: 00982188497384 email:[email protected] ©2016 JMLL, Tokyo, Japan
•
relieve mild dentin hypersensitivity, toothpastes containing strontium salts chloride or acetate) or potassium salts (chloride and nitrate) are often recommended 5). In case of severe dentin hypersensitivity affecting the quality of life, application of glass ionomers or photopolymerized sealants may be required to obstruct the dentinal tubules. In very severe cases of dentin hypersensitivity, more invasive procedures such as crown placement or root canal therapy may be indicated 6). The efficacy of some desensitizing agents containing Received date: May 30th, 2016 Accepted date: October 5th, 2016
Laser Therapy 25.4: 259-266
259
ORIGINAL ARTICLES glutaraldehyde has been confirmed in vitro and in vivo. Glutaraldehyde reacts with serum albumin in dentinal tubules and stimulates the polymerization of HEMA (2-hydroxyethyl-methacrylate) 7). Microleakage has also been reported to cause dentin hypersensitivity. Microleakage is defined as passage of bacteria and their products through the restoration-tooth interface and is one of the main reasons for replacement of restorations. Microleakage results in formation of marginal gaps and leads to development of secondary caries, post-operative tooth hypersensitivity or pulp involvement. Thus, it is extremely important for dental restorative materials to efficiently seal the margins 8). Considering the advances in dental materials and introduction of new materials with more favorable characteristics as well as high patient expectations, researchers investigate for ideal dental materials to achieve high patient satisfaction 9). Despite some reports of success in relieving dentin hypersensitivity, the success of most treatments is short-term, lasting for less than 6 months 10). Moreover, some desensitizing materials have a delayed effect and cause a late response in patients 11). Introduction of laser technology contributes to some fields of dentistry 2, 12, 13). In 1980, laser was used as an anti-inflammatory tool and stimulating neurons in clinical setting 14). Several studies have evaluated the application of different types of lasers to relieve dentin hypersensitivity. Lasers used for desensitization are divided into two main groups of low energy lasers and high energy lasers. The mechanism of action of low energy lasers is via blocking the nerve ends and affecting the inflammatory mediators, meanwhile mechanism of action of high energy lasers is via changing the structure of dentin to obstruct dentinal tubules 2). CO2 and Er:YAG lasers are highly popular in dentistry. Evidence shows that the smear layer is completely melted and evaporated following
available at www.jstage.jst.go.jp/browse/islsm
Er:YAG laser irradiation and results in deposition of insoluble salts at the orifice of the open dentinal tubules leading to their obstruction 15, 16). Studies have shown that Er:YAG laser irradiation results in insignificant thermal injury to the pulpal tissue, which is an advantage for this type of laser 17-19). On the other hand, CO2 laser concentrates high levels of energy in a small area. Energy is converted to heat and results in burning, melting or vaporization of the respective area in dentin. Melting and re-crystallization of dentin result in obstruction of dentinal tubules and dentin hypersensitivity may be relieved 8). This study aimed to assess the effect of three different desensitization treatments on marginal microleakage of composite restorations bonded with a two-step, etch and rinse adhesive. The null hypothesis is the application of desensitizing agents/methods prior to restoration do not affect the marginal seal of bonded composite restorations.
Material and methods A total of 60 sound extracted human molars were collected. The teeth were cleaned from debris using a periodontal curette and were then immersed in 0.1% thymol solution (Merck, NY, USA) for one week. The teeth were evaluated under a stereomicroscope at ×10 magnification to ensure absence of cracks and structural anomalies and were then stored in distilled water at 4°C. Class V cavities measuring 3mm in width, 2mm in depth and 3 mm in height were prepared in such way that 1.5 mm of the cavity height was above and 1.5 mm was below the cementoenamel (CEJ) junction using 008 diamond bur and a high-speed handpiece under water and air spray. All cavities were prepared by the same clinician. Materials were used in this study are shown in Table 1. The specimens were randomly divided into 4 groups (n=15) based on the desensitiz-
Table 1: Products used in this study Brand name
Chemical composition
Manufacturer
Gluma® Desensitizer
HEMA, Glutaraldehyde, Water
HeraeusKulzer South America Ltd.
Ultraetch
Phosphoric acid 37%
Ultradent, USA
SingleBond2
Bis-GMA, HEMA, Silanized silica, Glycerol 1,3 dimethacrylate, Diurethane Dimethacrylate, water, ethanol, polyalkenoic acid copolymer, photoinitiator
3M ESPE, MN,USA
Z250
UDMA,BisGMA,BisEMA,TEGDMA, zirconia/silica filler
3M ESPE, MN,USA
260
HR Mozaffari et al
available at www.jstage.jst.go.jp/browse/islsm
ing technique as follows: Group one (control group): No surface treatment Group two: Cavity surfaces were treated with Gluma® desensitizer (HeraeusKulzer Ltd., South America) according to the manufacturer’s instructions. Group three: Cavity surfaces were lased with CO2 laser (US-20D, Deka Dental Laser system, Florence, Italy) with settings of 1.5 W, 85 J/cm2, 10 Hz and 300 µs pulse width. Group four: Cavity surfaces were lased with Er:YAG laser (USD20, Deka Dental Laser system, Florence, Italy) with settings of 10 Hz, 50 mJ and 470 µs pulse width. One week after desensitizing treatment, specimens in all four groups were similarly etched with 37% phosphoric acid (Ultraetch, Ultradent, USA) for 15 seconds. The bonding agent (Single Bond 2, 3M ESPE, MN, USA) was then applied and light cured for 20 seconds, the cavities were restored with Z250 composite (3M ESPE, MN, USA) in 2mm increments according to the manufacturer’s instructions and cured for 20 seconds. All specimens were then thermocycled (3500 cycles) between 5-55°C for 30 seconds at each temperature
ORIGINAL ARTICLES with 15 seconds of transfer time. Root apices in all specimens was sealed with utility wax and the surfaces of specimens were coated with two layers of nail varnish except for 1mm around the restoration margins. The specimens were then immersed in 1% methylene blue solution for 24 hours. The specimens were then rinsed with water, dried and buccolingually sectioned in the middle of the cavity. The microleakage was scored under a stereomicroscope at × 20 magnification by one blind researcher using the following scoring system (figures 1-4): Grade zero: No dye penetration through the cavity margins. Grade one: Dye penetration to more than half of the cavity depth Grade two: Dye penetration through the entire length of the cavity wall but not reaching to the axial wall Grade three: Dye penetration through the entire length of the cavity wall and into the axial wall Data were analyzed using SPSS version 20. The difference in the microleakage among groups was analyzed using the Kruskal Wallis test.
Figure 1: Grade zero
Figure 2: Grade 1 at enamel margin
Figure 3: Grade 2
Figure 4: Grade 3
Microleakage in classV composite restorations
261
ORIGINAL ARTICLES
available at www.jstage.jst.go.jp/browse/islsm
Results Data were analyzed using SPSS version 20. The difference in the microleakage between groups was analyzed using the Kruskal Wallis test. Pairwise comparisons were made using Dunn’s test. P
ORIGINAL ARTICLES
Microleakage in Class V Composite Restorations after Desensitizing Surface Treatment with Er:YAG and CO2 Lasers Hamid Reza Mozaffari 1, Alireza Ehteshami 2, Farshad Zallaghi 2, Nasim Chiniforush 3, Zohreh Moradi 4
1: Oral Medicine Department, School of Dentistry, Kermanshah University of Medical Sciences 2: Dentist, Private Practice 3: Laser Research Center of Dentistry, Tehran University of Medical Sciences 4: Operative Department, School of Dentistry, Tehran University of Medical Sciences
Aims: Glutaraldehyde, CO2 and Er:YAG lasers can be used for treatment of dentin hypersensitivity. However, their application may have adverse effects on the clinical service of restorations. This study aimed to assess the microleakage in composite restorations following surface treatment with Glutaraldehyde desensitizer, CO2 and Er:YAG laser irradiation for treatment of dentin hypersensitivity. Materials and methods: This experimental study was conducted on 60 extracted sound human teeth. Class V cavities were prepared measuring 3×3 mm using a diamond bur. Specimens were randomly divided into 4 groups of 15. Group one:no surface treatment, Group two:applying Glutaraldehyde desensitizer, Groups of three and four were irradiated with CO2 and Er:YAG lasers, respectively. Surfaces were restored with bonding agent(Single Bond 2, 3M, USA) and Z250 composite (3M,USA). Specimens were thermocycled and immersed in 1% methylene blue solution for 24 hours. Microleakage scores were assessed under a stereomicroscope at ×20 magnification. Data were analyzed using SPSS and the Kruskal Wallis test (P=0.05). Results: There was no significant difference between microleakage of groups in enamel margins (P=0.694). The difference in microleakage at the dentin margin was significant between groups (P=0.018). Conclusions: Application of Glutaraldehyde-desensitizer and CO2 laser irradiation of surfaces prior to composite restoration do not increase microleakage at the enamel or dentin margins but tooth surface treatment with Er:YAG laser significantly increased the microleakage at the dentin margins. Key words: Dentin hypersensitivity • CO2 laser • Er:YAG laser • Glutaraldehyde desensitizer Microleakage
Introduction Dentin hypersensitivity is the most common patient complaints and is defined as pain and discomfort in response to cold, hot, chemical and osmotic stimuli due to exposed cervical dentin 1, 2). The prevalence of dentin hypersensitivity ranges from 3.8 to 57% 3, 4). To Addressee for Correspondence: Zohreh Moradi Iran,Tehran,North Amirabad Ave, Dental Faculty of Tehran University of Medical Sciences Tel: 00982188497384 email:[email protected] ©2016 JMLL, Tokyo, Japan
•
relieve mild dentin hypersensitivity, toothpastes containing strontium salts chloride or acetate) or potassium salts (chloride and nitrate) are often recommended 5). In case of severe dentin hypersensitivity affecting the quality of life, application of glass ionomers or photopolymerized sealants may be required to obstruct the dentinal tubules. In very severe cases of dentin hypersensitivity, more invasive procedures such as crown placement or root canal therapy may be indicated 6). The efficacy of some desensitizing agents containing Received date: May 30th, 2016 Accepted date: October 5th, 2016
Laser Therapy 25.4: 259-266
259
ORIGINAL ARTICLES glutaraldehyde has been confirmed in vitro and in vivo. Glutaraldehyde reacts with serum albumin in dentinal tubules and stimulates the polymerization of HEMA (2-hydroxyethyl-methacrylate) 7). Microleakage has also been reported to cause dentin hypersensitivity. Microleakage is defined as passage of bacteria and their products through the restoration-tooth interface and is one of the main reasons for replacement of restorations. Microleakage results in formation of marginal gaps and leads to development of secondary caries, post-operative tooth hypersensitivity or pulp involvement. Thus, it is extremely important for dental restorative materials to efficiently seal the margins 8). Considering the advances in dental materials and introduction of new materials with more favorable characteristics as well as high patient expectations, researchers investigate for ideal dental materials to achieve high patient satisfaction 9). Despite some reports of success in relieving dentin hypersensitivity, the success of most treatments is short-term, lasting for less than 6 months 10). Moreover, some desensitizing materials have a delayed effect and cause a late response in patients 11). Introduction of laser technology contributes to some fields of dentistry 2, 12, 13). In 1980, laser was used as an anti-inflammatory tool and stimulating neurons in clinical setting 14). Several studies have evaluated the application of different types of lasers to relieve dentin hypersensitivity. Lasers used for desensitization are divided into two main groups of low energy lasers and high energy lasers. The mechanism of action of low energy lasers is via blocking the nerve ends and affecting the inflammatory mediators, meanwhile mechanism of action of high energy lasers is via changing the structure of dentin to obstruct dentinal tubules 2). CO2 and Er:YAG lasers are highly popular in dentistry. Evidence shows that the smear layer is completely melted and evaporated following
available at www.jstage.jst.go.jp/browse/islsm
Er:YAG laser irradiation and results in deposition of insoluble salts at the orifice of the open dentinal tubules leading to their obstruction 15, 16). Studies have shown that Er:YAG laser irradiation results in insignificant thermal injury to the pulpal tissue, which is an advantage for this type of laser 17-19). On the other hand, CO2 laser concentrates high levels of energy in a small area. Energy is converted to heat and results in burning, melting or vaporization of the respective area in dentin. Melting and re-crystallization of dentin result in obstruction of dentinal tubules and dentin hypersensitivity may be relieved 8). This study aimed to assess the effect of three different desensitization treatments on marginal microleakage of composite restorations bonded with a two-step, etch and rinse adhesive. The null hypothesis is the application of desensitizing agents/methods prior to restoration do not affect the marginal seal of bonded composite restorations.
Material and methods A total of 60 sound extracted human molars were collected. The teeth were cleaned from debris using a periodontal curette and were then immersed in 0.1% thymol solution (Merck, NY, USA) for one week. The teeth were evaluated under a stereomicroscope at ×10 magnification to ensure absence of cracks and structural anomalies and were then stored in distilled water at 4°C. Class V cavities measuring 3mm in width, 2mm in depth and 3 mm in height were prepared in such way that 1.5 mm of the cavity height was above and 1.5 mm was below the cementoenamel (CEJ) junction using 008 diamond bur and a high-speed handpiece under water and air spray. All cavities were prepared by the same clinician. Materials were used in this study are shown in Table 1. The specimens were randomly divided into 4 groups (n=15) based on the desensitiz-
Table 1: Products used in this study Brand name
Chemical composition
Manufacturer
Gluma® Desensitizer
HEMA, Glutaraldehyde, Water
HeraeusKulzer South America Ltd.
Ultraetch
Phosphoric acid 37%
Ultradent, USA
SingleBond2
Bis-GMA, HEMA, Silanized silica, Glycerol 1,3 dimethacrylate, Diurethane Dimethacrylate, water, ethanol, polyalkenoic acid copolymer, photoinitiator
3M ESPE, MN,USA
Z250
UDMA,BisGMA,BisEMA,TEGDMA, zirconia/silica filler
3M ESPE, MN,USA
260
HR Mozaffari et al
available at www.jstage.jst.go.jp/browse/islsm
ing technique as follows: Group one (control group): No surface treatment Group two: Cavity surfaces were treated with Gluma® desensitizer (HeraeusKulzer Ltd., South America) according to the manufacturer’s instructions. Group three: Cavity surfaces were lased with CO2 laser (US-20D, Deka Dental Laser system, Florence, Italy) with settings of 1.5 W, 85 J/cm2, 10 Hz and 300 µs pulse width. Group four: Cavity surfaces were lased with Er:YAG laser (USD20, Deka Dental Laser system, Florence, Italy) with settings of 10 Hz, 50 mJ and 470 µs pulse width. One week after desensitizing treatment, specimens in all four groups were similarly etched with 37% phosphoric acid (Ultraetch, Ultradent, USA) for 15 seconds. The bonding agent (Single Bond 2, 3M ESPE, MN, USA) was then applied and light cured for 20 seconds, the cavities were restored with Z250 composite (3M ESPE, MN, USA) in 2mm increments according to the manufacturer’s instructions and cured for 20 seconds. All specimens were then thermocycled (3500 cycles) between 5-55°C for 30 seconds at each temperature
ORIGINAL ARTICLES with 15 seconds of transfer time. Root apices in all specimens was sealed with utility wax and the surfaces of specimens were coated with two layers of nail varnish except for 1mm around the restoration margins. The specimens were then immersed in 1% methylene blue solution for 24 hours. The specimens were then rinsed with water, dried and buccolingually sectioned in the middle of the cavity. The microleakage was scored under a stereomicroscope at × 20 magnification by one blind researcher using the following scoring system (figures 1-4): Grade zero: No dye penetration through the cavity margins. Grade one: Dye penetration to more than half of the cavity depth Grade two: Dye penetration through the entire length of the cavity wall but not reaching to the axial wall Grade three: Dye penetration through the entire length of the cavity wall and into the axial wall Data were analyzed using SPSS version 20. The difference in the microleakage among groups was analyzed using the Kruskal Wallis test.
Figure 1: Grade zero
Figure 2: Grade 1 at enamel margin
Figure 3: Grade 2
Figure 4: Grade 3
Microleakage in classV composite restorations
261
ORIGINAL ARTICLES
available at www.jstage.jst.go.jp/browse/islsm
Results Data were analyzed using SPSS version 20. The difference in the microleakage between groups was analyzed using the Kruskal Wallis test. Pairwise comparisons were made using Dunn’s test. P
