Irfan Qamruddin*, Adel Z Siddiqui**, Qamar Aziz***, Sidra Butt****
- Assistant Professor & Head Department of Orthodontics, Baqai Dental College/ Baqai Medical University, Karachi.
- Assistant Professor, Department of Dental Material, Baqai Dental College / Baqai Medical University, Karachi.
- Assistant Professor, Department of Pathology Baqai Medical University, Karachi.
- Demonstrator, Department of Orthodontics, Baqai Dental College / Baqai Medical University, Karachi.
Correspondance :“Dr. Irfan Qamruddin” <drirfan_andani@yahoo.com>
How to CITE:
J Pak Dent Assoc.2010; 19(4): 198-201
OBJECTIVE:
To evaluate the antibacterial activity of 0.2% aqueous chlorhexidine digluoconate mixed with alginate or used as mouth rinse before taking impression and to compare with conventional type of impression mixed with distilled water.
METHODOLOGY:
A total of 3 impressions of each subject were taken using alginate impression material with the interval of 24 hrs between them. First impression (IMP 1) was made by mixing alginate with distilled water which served as control. Second impression (IMP 2) was made after the subjects rinsed with 0.2% chlorhexidine digluconate containing mouthwash and third impression (IMP 3) was made with alginate mixed with 0.2% aqueous chlorhexidine digluconate. Impressions were cultured immediately for 4 strains of bacteria i.e. Streptococcus Viridans, Staphylococcus Epidermidis, Streptococcus Pneumonia and Staphylococcus Aureus. Based on the number of bacterial colonies observed microscopically, all the three categories of impressions were compared statistically using Wilcoxon signed rank test.
RESULT:
Marked number of bacterial colonies were observed in control specimen while significant reduction in bacterial count was seen in other experimental groups (p<0.05). No significant difference was observed amongst both the experimental groups (p=0.617)
CONCLUSION:
0.2% chlorhexidine digluconate proved to be an efficient impression disinfectant when used as a pre-procedural mouth rinse or as an alternate to water while mixing with alginate
KEYWORDS:
Irreversible hydrocolloid; disinfectant; internal disinfection; Pre-procedural rinse.
Introduction
Dental impressions are considered to be a backbone of dental procedures whether taken for restoration, prosthesis or for making orthodontic casts. Contamination of dental impressions with patient’s
saliva, bacterial plaques, and blood is not unusual, which can transmit infectious agents to dental personnel and patients.1 If casts are poured from contaminated impressions, microorganisms are transferred to gypsum models which can be distributed throughout the laboratory while trimming of casts or dies and affect the be taken for strict control of cross infections.
Since sterilization of dental impressions is not possible, because of the high temperature and time needed, disinfection is the preferred method. Disinfectant must effectively kill microorganisms without affecting precision of the impression. Glutaraldehyde, Sodium hypochlorite, Iodophores and Phenolics are the common disinfectants used either in the form of spray or solution in which impressions are immersed for recommended time. 4
World Health Organization (WHO) recommends immersion in 2% Glutaraldehyde or 1% Sodium hypochlorite solution for 60 minutes5 but hydrophilic irreversible hydrocolloid (Alginate) which is the most commonly used material, undergo dimensional changes and distortion.1,4,6 Although clinically insignificant dimensional changes have been noticed when alginate impression is subjected to short-term immersion or spray technique7,8 but compliance by dental clinics has been found uneven. 9
The difficulties associated with disinfecting irreversible hydrocolloid impression material and poor compliance by clinicians have resulted in the development of some more disinfection techniques; which includes Pre-procedural mouth rinsing with chlorhexidine digluconate or any other appropriate disinfectant;10,11,12 Internal disinfection by replacing water with disinfectant iodine or chlorhexidine while mixing the material13,14 and use of self-disinfecting irreversible hydrocolloid impression materials that are pre-impregnated with disinfectants. 14, 15 . The purpose of the study is to compare the effect of pre-procedural mouth rinses and internal disinfection method on bacterial count of impressions; using 0.2% aqueous chlorhexidine digluconate. It was hypothesized that both the methods using 0.2% aqueous chlorhexidine digluconate, reduce the bacterial count on impressions.
Methodology
The study was conducted in the Department of Orthodontics at Baqai Dental College, Baqai Medical University. Fifty subjects with complete permanent dentition (excluding third molars) with the age ranging from 15 to 40 years were randomly selected for the research. Patients with poor oral hygiene, any oral or dentofacial pathology, high caries index and with any removable or fixed prostheses were excluded from the study .A total of 3 impressions of maxillary arch of each subject were made using irreversible hydrocolloid impression material i.e. Alginate (Kromopan Lascod Italy). First impression (IMP 1) was made by mixing alginate with distilled water, using sterilized impression trays. The mixing spatula and rubber bowl was disinfected prior to mixing alginate. Immediately after taking impression 10 x 10 mm piece of alginate was cut from the palatal surface of the impression, with the help of sterile knife and the exposed surface was applied on Blood agar and MacConkeys agar with the help of sterile forceps. The culture-medium plates were incubated at 37°C for 24 hrs. Smear from the culture plate were taken on slide to examine bacterial growth quantitatively and qualitatively under microscope. On the basis of number of bacterial colonies observed, dental impression was allocated into groups. Group A: If no bacterial colony is observed; Group B: If less than 10 bacterial colonies were seen; Group C: If 10-100 bacterial colonies were observed and Group D: If more than 100 bacterial colonies were seen. Colonies were also identified by means of their morphological features, gram staining method, biochemical test and sensitivity testing. A total of 4 bacterial strains were assessed, namely Streptococcus Viridans, Staphylococcus Epidermidis, Streptococcus Pneumonia and Staphylococcus Aureus . Second impression (IMP 2) was made 24 hours after initial impression prior to which the patient rinsed with mouthwash containing 0.2% chlorhexidine digluconate for a minute. Whereas third impression (IMP 3) of the same subject was made 48 hours after IMP 1, with Alginate mixed with 0.2% chlorhexidine digluconate. Rest of the steps for evaluation of the impressions for bacterial growth and colonies identification were same as used for IMP 1. Data was recorded and analyzed for difference in the bacterial count between IMP 1, IMP 2 and IMP 3 using non parametric Wilcoxon signed rank test from SPSS version 10.
Results
Considerable number of bacterial colonies was found in IMP 1 as none of the patient’s impression was allocated in Group A and B (table 1). Significant reduction in the number of bacterial colonies was observed in second and third categories of impressions (IMP 2 & IMP3) which showed that 0.2% chlorhexidine digluconate is effective whether used for pre-procedural rinses or in an internal disinfection method (Table 1).
All the tested bacterial strains were found in IMP 1 whereas only Streptococcus Viridians were noticed in IMP2 and IMP3. Few colonies of Staphylococcus
Epidermidis were also seen in IMP3 merely in 5 subjects (Fig 1).
Comparative analysis of IMP 1 and IMP 2 shows significant decrease in number of colonies in the second category of impression (p=0.00) as seen in table 2
Similarly, internal disinfection method (IMP3) also resulted in marked decline in number of bacterial colonies when compared with (IMP1) (p=0.00) can be depicted from table 3.
Table 4 shows that Pre-procedural rinsing was found to be quite similar to the internal disinfection method and both methods are equally effective in microbial reduction (p=0.617).
Discussion
The dental team is constantly exposed to various types of infectious microorganisms and this demands strict precautions to avoid cross infections. Regarding spread of infections through irreversible hydrocolloid impressions, various methods have been applied.15 In our study two different impression disinfection methods were analyzed i.e. internal disinfection method and pre-procedural mouth rinsing. 0.2% aqueous chlorhexidine digluconate was used as disinfectant in both the methods. As evident from present study, pre-procedural rinses and internal disinfection method both resulted in marked reduction in the bacterial count on the surface of impressions (table 1). Both the techniques were more or less equally effective against all the tested bacterial strains (Fig 1) which can be explained from the fact that chlorhexidine is a broad-spectrum chemical antiseptic effective against vegetative gram positive and gram negative microbes, although some gram negative microbes are resistant to it.16,17 The results revealed that there was significant decrease in the number of bacterial colonies in IMP 2 and IMP 3 when compared with IMP1 (p <.05) while the antimicrobial activity of both the techniques were found equally reliable (p=0.617).
Internal disinfection method has been emphasized in several other researches and considered as a method of choice for alginates.18 The reason of being the preferred method is the dimensional stability and accuracy of impression which is not affected because of possibility of immediate pouring.18-23 This method can disinfect the impressions internally because it eliminates microorganisms penetration while setting, unlike the spray and immersion techniques which provide surface disinfection only.9,19,24,25 Furthermore possibility of contaminating immune-compromised patients who are susceptible to infections would be decreased because impression material itself is not free from microorganisms.2 6 , 2 7 Pre-procedural rinsing with antimicrobial agent is also an efficient method for impression disinfection. Many studies have demonstrated that pre-procedural rinsing with antimicrobial agent like Chlorhexidine, essential oils or povidone Iodine can reduce the level of oral microorganisms in aerosols and spatter during dental procedures.27-31 Veksler32 also reported that Pre-procedural rinsing with chlorhexidine has a profound effect on the aerobic and facultative flora of the oral cavity. American Dental Association (ADA) and American Heart Association (AHA) also recommend pre-procedural rinsing with antimicrobial mouth rinses although data regarding its effect on dental impressions is still deficient. 33 The study demonstrated that the use of 0.2% chlorhexidine digluconate for internal disinfection method or for pre-procedural mouth rinsing, reduces the tested strains of bacteria from the impressions effectively. However it is important to recognize the limitations of antimicrobial activity of techniques against other pathogens and it would be of interest to test the efficiency of these methods against more harmful pathogens like HIV, Hepatitis B & C etc.
Conclusion
0.2% aqueous chlorhexidine digluconate has a profound effect in bacterial growth inhibition whether used as a mouth rinsing solution prior to impressions or mixed with irreversible hydrocolloid impression material. Pre-procedural rinsing and internal disinfection method both were equal in efficacy and can be used alternatively
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