Streptococcus Mutans Group And Lactobacillus Counts In Proximal Amalgam And Resin Composite Restorations: An In Vivo Study Juliana Campos Junqueira, 1 Alessandra Bühler Borges, 2 Daphne Câmara Barcellos, 3 Cinthya Lobo Pradella, 4 Antonio Olavo Cardoso Jorge, 5 Carlos Rocha Gomes Torres 6 ABSTRACT Aim & Objectives: This study assesses the quantity of streptococcus mutans group and lactobacillus in interproximal contact of posterior teeth with proximal amalgam and resin composite restorations. Methods: Twenty patients were divided into two groups (n=10) according to the type of restorative material they presented: amalgam (AM) or resin composite (RC). In the same patient, one interproximal Class II amalgam or resin composite restoration and one interproximal contact without restorations (control group – C) were studied. The material was collected from the interproximal with the aid of a piece of sterilized dental thread, and stored in phosphate buffered saline solution. The material was seeded on plates containing Mitis Salivarius Bacitracin Sucrose agar and Rogosa agar culture medium and incubated at 37C for 48-72h. The colony forming units (Log 10 CFU/mL) were counted and the data were submitted to the Student’s-t test (5%). Results: There was significant difference between Groups C and AM (p=0.019) with regard to lactobacillus count. For streptococcus mutans group, there was significant difference between Groups C and RC (p=0.015). Conclusion: There is significantly greater growth of streptococcus mutans group in RC Class II restorations and lactobacillus in AM restorations when compared with interproximal contact without the presence of restorations. KeyWords: Biofilms, lactobacillus, restorative materials, streptococcus mutans group. capable of adhering to the surface of the dental enamel, they are mainly responsible for the initial phase of caries lesion. These microorganisms have been strongly associated with the increase in the risk of caries when detected in high numbers in the saliva (2). As lactobacillus has a lower capacity to adhere to the tooth surface, they are more associated with the subsequent development of the lesion (2). However, the lactobacillus count may also be used as predictive of caries and the increase in the number of these microorganisms is related to the risk of caries(3). The quantity of microorganisms varies according to the location assessed in the oral cavity. The highest number of microorganisms is found in the biofilm of molars, followed by pre-molars and anterior teeth(3,4). Greater colonization by microorganisms is also verified on the vestibular surface of teeth, followed by the interproximal, occlusal and lingual faces (4). According to Lindquist and Emilson (5) (1990), the surfaces of teeth with restorations are shown to be more colonized by microorganisms than the healthy faces (6). The principal etiologic agents that initiate and propagate dental diseases are permanent inhabitants of the biofilm formed on teeth and restorations. Dental materials release different substances, which might be able to influence the growth of bacteria directly (7). Thus, in view of the above discussion, the aim of this in vivo study was to correlate the number of streptococcus mutans group and lactobacillus in amalgam and resin composite restorations in the interproximal contact of posterior teeth. The null hypothesis tested was that the streptococcus mutans group and lactobacillus counts do not differ in teeth with amalgam and resin composite restorations when compared with healthy teeth. Materials and Method This study was approved by the Research Ethics Committee of the São Jose dos Campos School of Dentistry - UNESP (Protocol No. 082/2004-PH/CEP). Twenty patients between the ages of 18 and 50 Introduction Dental caries is a multifactorial disease, requiring a susceptible host, a cariogenic microbiota and an acidogenic substrate, which must be present in the mouth for a sufficient length of time and interact under critical conditions (1). Microbiological techniques to detect cariogenic microorganisms enable the early detection of individuals with a high risk of caries. The microbiological factors that have been studied are mainly concerned with the number of streptococcus mutans group and lactobacillus in dental biofilm or saliva (1). Because the streptococcus mutans group is capable of adhering to the surface of the dental 80 IJCD • AUGUST, 2011 • 2(4) © 2011 Int. Journal of Contemporary Dentistry RESEARCH