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ORIGINAL RESEARCH
Year : 2023 | Volume
: 14
| Issue : 1 | Page : 16-18
Early and Delayed Effect of Cavity Disinfection with Chlorhexidine and Ozone on the Shear Bond Strength of Dentin to Glass Hybrid Restoration: An In Vitro Study
Murtatha M AL-Anezi, Shahbaa M Abduljabar
Department of Pedodontics and Preventive Dentistry, College of Dentistry, University of Baghdad, Baghdad, Iraq
Correspondence Address:
Murtatha M AL-Anezi
Department of Pedodontics and Preventive Dentistry, College of dentistry, University of Baghdad, Baghdad
Iraq
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/denthyp.denthyp_147_22
Introduction: We aimed to evaluate the early and delayed effects of chlorhexidine (CHX) and ozone disinfection on the shear bond strength (SBS) of dentin to glass hybrid restoration. Methods: The occlusal surfaces of 60 extracted premolars were trimmed to obtain a flat dentinal surface and randomly divided into three groups, including distilled water (control), 2% CHX, and ozonized water. Each group was further subjected to a shear bond strength test after 24 hours and 3 months. Results: The overall model test (P < 0.001), disinfectant and time (P < 0.001), and time (P = 0.017) showed statistically significant differences among study groups. Yet, the type of disinfectant revealed a non-significant difference (P = 0.238). Post hoc tests showed SBS significantly decreasing over time in the control group (P < 0.001) while the difference between 24 hours and 3 months for the CHX (P = 0.880) and ozone (P = 0.983) groups was not significant. Conclusion: Within the inherent limitations of in vitro studies, it can be concluded that cavity disinfection with CHX and ozone before glass hybrid restoration had a significant effect on the stability of SBS to dentin over 3 months. The type of disinfectant revealed non-significant difference.
Keywords: Cavity disinfection, chlorhexidine gluconate, dentine, glass hybrid restoration, ozone, ozonized water, shear bond strength
Bacterially contaminated cavity walls associated with caries are a potential problem in restorative dentistry. Bacteria can remain in the smear layer or in the dentinal tubules and can potentially multiply. Studies indicate that residual bacteria may proliferate from the smear layer beneath restorations, allowing toxins to diffuse to the pulp and thereby resulting in irritation and inflammation. These problems cannot be overcome by incorporating antibacterial agents into the restorative materials.[1] An alternative strategy would be cavity disinfectant to reduce or eliminate the microorganisms from cavity.
Chlorhexidine (CHX) is widely used in clinical dentistry as an antimicrobial agent in addition to having a potential to reduce postoperative sensitivity. Its use may interfere with adhesive procedures on dentin. Although many studies have described the influence of CHX on the bond strength of composite restoration,[2] its early and delayed effect on glass hybrid restoration is still unclear.
Ozone is an influential oxidizing agent that has been introduced in dental practise as an antimicrobial agent against common oral pathogens. Clinical studies assessed the effect of ozone on dental hard tissues as a cavity disinfectant before adhesive restorations.[3] The effect of ozone on the bond strength of glass hybrid restoration is still unknown.
Nevertheless, the aim of the study was to evaluate the early and delayed effects of CHX and ozone disinfection on the shear bond strength (SBS) of dentin to glass hybrid restoration.
Materials and MethodsThe research ethics comitties of Baghdad University/College of Dentistry approved the study protocol (approval number: 728, Dec 1, 2022). Sixty sound (free from cracks and caries) human maxillary first premolar teeth were extracted for orthodontic reason and restored in 0.1% thymol solution (Flinn scientific, Batavia, Indonesia).
The teeth were mounted in self-cured acrylic resin (Veracril, Guarne, Colombia) by using a specially designed rubber mold. A flat surface for bonding was obtained by cutting the buccal and palatal cusps. The sectioning was done by a sectioning device (Hobbymat, Dusseldorf, Germany) and a diamond cutting disc (thickness 1 mm) (Yihong Abrasives, Zhengzhou, China). The occlusal surface of each tooth was then ground against the flat, wet surface of abrasive paper (Xuchang Sanshun, Henan, China). Each surface was ground four times, and the occlusal surfaces of all teeth were observed to check for the presence of any remnant enamel.[4],[5]
To produce Ozonized water, 5 mL of distilled water were sparged with ozone gas from an ozone generating apparatus (Aqua-8, KY, USA) with a range of 300s (about 1000 mg/L).[6]
The selected 60 teeth were divided randomly (using www.graphpad.com/quickcalcs/randomN1/) into three main groups of 20 teeth, 1. Control: Teeth were treated with distilled water for 20 seconds. 2. CHX: Teeth were treated by 2% CHX (Cerkamed, Stalowa Wola, Poland) for 20 seconds. 3. Ozone (O3): Teeth were treated by ozonized water for 80 seconds. All samples were rinsed for 15 seconds and dried, then exposed to conditioner for 20 seconds, rinsed for 15 seconds, dried without desiccating and restored [7].
Bulk fill high viscosity glass hybrid (GH) Equia forte HT (ultra-fine, highly reactive glass, and high molecular weight polyacrylic acid powders within conventional glass) (GC, Tokyo, Japan) was applied on the prepared teeth according to manufacturer instruction by using a mold especially designed for standardization of GH application. This mold was custom made from Teflon material (Asiga, Alexandria, Australia) with a hole in the center that has a diameter of 4 and 2 mm height for application of Equia forte HT in a standardized manner.[4]
Each group was further subdivided into two subgroups (n = 10), subgroups 1 were subjected to shear bond strength test after 24 hours and subgroups 2 after 3 months. All the samples were soaked in artificial saliva (Albasheer Scientific Bureau, Baghdad, Iraq) contained in plastic containers, and stored in an incubator at 37°C until the time of the shear bond strength test. The artificial saliva was changed during each week of storage to minimize the risk of bacterial growth.
SBS of Equia forte HT to dentin was tested using a universal testing machine (Laryee WDW-50, Jinan, China) at a crosshead speed of 0.5 mm/min. The acrylic blocks were fixed to the lower jaw of the testing machine in such a way that the chisel rod was held perpendicular to the restorative tooth interface from the buccal aspect, and the test continued until failure.
Data were analyzed blindly using two-way analysis of variance (ANOVA) and Tukey’s post hoc test using R software (R Foundation for Statistical Computing, Vienna, Austria).
ResultsOverall, the model test (P < 0.001), disinfectant (P < 0.001), and time (P = 0.017) showed statistically significant differences among study groups. Yet, the type of disinfectant revealed a non-significant difference (P = 0.238). Post hoc tests showed SBS significantly decreasing over time in the control group (P < 0.001), while the difference between 24 hours and 3 months for the CHX (P = 0.880) and ozone (P = 0.983) groups was not significant [Figure 1].
Figure 1 Box and whisker plot displaying variation in shear bond strength (MPa) among different times and disinfectants. Discussion Results of this study showed cavity disinfection with CHX and ozone before glass hybrid restoration had a significant effect on the stability of SBS to dentin over 3 months. The type of disinfectant revealed non-significant difference.
Shafiei et al., showed pretreatment with CHX significantly increased the SBS of etch-and-rinse and self-etch cements to dentin over a 1 year follow up period with thermocycling. They reported a non-significant effect on self-adhesive cement.[7] Deniz et al. demonstrated early SBS of dentin to adhesive resin cement, which improved with CHX pretreatment and the use of a universal adhesive system.[8] Stanislawczuk et al. showed that the usage of aqueous CHX, alone or in combination with the acid conditioner, preserved the stability of the resin–dentin interface following 2 years.[9] On the other hand, Galo et al. reported that application of CHX during and after etching significantly decreased SBS total etching system to dentin.[10] A comprehensive meta-regression analysis, which involved 14 articles, concluded that the relationship between the concentration of CHX and bond strength is not a linear association and depended to several variables such as adhesive area, adhesive system, storage time, CHX application medium, and time may be influential.[2]
Assessment of the effect of ozone on SBS is rarely reported in the literature. Akturk et al. reported that the pretreatment with ozonized water significantly increased the early SBS of two-step universal and self-etch adhesive systems to dentin.[11] These results agreed with Ibraheem and Habeeb, who found that ozonated water treated dentin showed significantly superior SBS than distilled water treated dentin.[12]
Schmidlin showed pretreatment with ozone gas had non-significant effect on early SBS etch-and-rinse and self-etch adhesive system to enamel.[3]
Prabhakar et al. showed that pretreatment with ozonized water and CHX had a non-significant effect on early SBS of resin-modified glass ionomer restoration to the dentin of primary molars.[13]
Nevertheless, readers must consider the limitations of this study. The thermocycling process was not used during the 3-month delay period. This process was used to relatively simulate an oral environment. Another weakness of this study was the limited sample size. Considering the inherent limitations of in vitro studies, more clinical trials are necessary to evaluate the effect of pretreatment with CHX and ozone on the stability of glass hybrid restoration.
Financial support and sponsorship
Nil.
Conflicts of interest
The authors report no conflicts of interest.
References
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