Association of age and sex of patients undergoing class 2 amalgam restoration in mandibular premolars

Aishwarya S1, Pradeep S*2, Suresh V3 1Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha university, Chennai77, Tamil Nadu, India 2Department of Conservative Dentistry and Endodontics, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Saveetha university, Chennai-77, Tamil Nadu, India 3Department of Prosthodontics, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences (SIMATS), Chennai-77, Tamil Nadu, India


INTRODUCTION
Class 2 restoration is de ined as the restoration done in a cavity that is present on the proximal surfaces of premolars and molars (GV Black). The most versatile restorative materials in the ield of dentistry are dental amalgam which constitutes 75% of all restorative materials used by dental practitioners. Due to its excellent load-bearing capacity and low costs, it is still the top priority for many dentists (Bharti et al., 2010). The major advantage of amalgam restorations is resistance to fracture and wear tolerance. In Spite of the presence of other direct restorative material, silver amalgam is still claimed to be more commonly used in posterior restorations due to its ability to resist masticating forces and obtain adequate interdental contacts in proximo occlusal cavities (Mathew et al., 2006).
Whenever posterior proximal caries is present, the amalgam is the irst and foremost material used for the conservative management of proximal caries. Amalgam is considered to be an excellent restorative material in producing inished and polished surface of the tooth structure and also it is evident that it has plaque resistant properties and it is indicated only in cases where adequate tooth structure is present (Gilmore and Lund, 1973). Nominal removal of sound tooth structure requires conservative cavity preparations for amalgam restorations and to maintain the strength of the tooth (Mondelli, 1998).
The fortune of class 2 amalgam restoration on the signi icance of the cavity design, the extent of caries on the proximal aspect. In the longitudinal clinical trials, the positive outcome of amalgam restoration is found to be equal or greater than composite resin restorations (Smales et al., 1990;Mjör and Jokstad, 1993;Mair, 1998). However in cross-sectional retrospective studies, based on restorations placed generally follow, the constancy of amalgam restoration is two times as much as composite restoration (Jokstad et al., 1994;Mjör, 1997;Mjör et al., 2000). Placement of the base, its adequate thickness depends on the depth of the cavity. The type of base used, liner, or varnish is determined by remaining Dentin Thickness (RDT). This helps to prevent damage to dentopulpal tissue (Dawson et al., 2015).
In a study by Bernardo et al. (2007), the composite restorations have 3.5 times higher failure rates compared to amalgam restoration due to secondary caries. Collins et al. (1998) reported that composite restorations fail at a rate two to three times higher than that of amalgam restorations (5,8%) after 8 years of observation. The potential bene it of using dental amalgam restoration is that they are strong and long-lasting, so they are less likely to break than some other types of illing. It is the least expensive type of illing material (Pereira, 2016). In the long run, the result of dental amalgam restoration will be good provided, if the cavity preparation and marginal seal are proper and intact. The median survival time for amalgam was reported twice when compared to composite resin (Mjör et al., 2000). Patient choice, since it is of less cost, it will be an affordable choice of restoration to all categories of patients. In this study, we intend to analyze the number of persons who underwent class II amalgam restorations in mandibular premolars.

Study setting
This retrospective study is done under the university setup, conducted in Saveetha Dental College. Class 2 amalgam restored patients were included for this study. Approval was obtained from the institutional committee [IEC], 2 examiners were involved in the study.

Sample Collection
The details of the 86,000 patient records were reviewed and analyzed, out of which 160 patients who had undergone class 2 amalgam restoration in mandibular premolars between June 2019 to March 2020 were included in this study. Cross veri ication of data for error was done by the presence of additional reviewers and by photographic evaluation. Simple random sampling was done to minimize sampling bias. It was generalized to the South Indian population.

Data Collection/Tabulation
The records of all the patients who underwent Class 2 amalgam restoration in mandibular premolars were collected from the initial to last in the chronological order. The data veri ication was done based on age and sex surfaces (MO, DO, MOD). The data was methodically entered in the excel sheet and was imported to SPSS. Incomplete or censored data were excluded from the study.

Analysis
IBM SPSS 23 software was used for data analysis independent variables including age, gender, and dependent variable include surfaces (MO, DO, MOD). Descriptive and inferential statistics were used. Descriptive statistics include the frequency of distribution of age, sex, and surface, while inferential test includes the chi-square test.

RESULTS AND DISCUSSION
Out of 160 patients, 66 of them were males and 94 patients were females. On analyzing the age group: 18-30 yrs (21.3%), 31-40 yrs (24.4%), 41-50 years (28.7%) and age above 50 years (25.6%) underwent class II amalgam restorations in a mandibular molar, patient over the age group of 40 years had more class II amalgam restorations. 28.7% of patients who belonged to age between 41-50 years and 25.6% patients who were greater than 50 years, these groups of patients had undergone more number of class 2 amalgam restorations (Table 1).
On analyzing the surfaces of restorations involved in mandibular irst and second premolars. In the mandibular irst premolar, the surface of restorations found to be in MO and DO, whereas in the mandibular second premolar all three surfaces were restored namely: MO, MOD and DO. It is evident that there is no statistically signi icant difference seen between teeth to the surfaces restored, the p-value was 0.373 in chi-square test (p>0.05) (Figure 1). On observing the number of surfaces involved in males and females, males were recorded with all the three surfaces (MO, DO, MOD) and females with two sur-faces (MO, DO). The relation between gender, surface cross-tabulation, we can contemplate that pvalue is 0.038 and which is statistically signi icant as p-value is <0.05, which is represented in (Figure 2).
In Figure 1, X-axis denotes the teeth and the Y-axis denotes the number of Class II amalgam restorations. Disto occlusal restorations (Green) were predominantly done in both the teeth when compared to Mesio occlusal restorations (Blue). However, Chisquare test p-value = .373, statistically no signi icant difference seen (p>0.05) In Figure 2, X-axis represents the gender and Y-axis represents the number of Class II amalgam restorations. Female patients had more Disto occlusal (Green) and Mesio occlusal (Blue) compared to male patients. Chi-square test p-value = .038, Statistically signi icant difference seen (p < 0.05) implying female patients had more class II amalgam restorations.
In this study, we can contemplate that there is a signi icant association between gender and surface distribution in mandibular premolar p (<0.05). Also, it is observed in both age groups and gender, the disto occlusal restoration is more commonly done. The study was done by Shashank et al., where he stated that MOD cavity preparations showed the highest fracture resistance value compared to MO, DO, box cavities. Ghaderi and Mardani (2015) have stated that the clinical success rate of class 2 compomers outweighs the amalgam restoration in the irst primary molars (Kavvadia, 2004).
The amalgam restorations are still in clinical practice due to its high tensile strength, its resistance to masticatory stress in posterior teeth. Studies of Soncini et al. (2007) have suggested the longevity of amalgam is higher as compomers are more repeatedly replaced owing to secondary caries and composition requires seven times as many repairs as did amalgam restoration.
The various microbiological studies have revealed the growth and presence of streptococcus mutants in the margins of the composite restoration. Their existence had been attributed due to the degradation of the hybrid layer in the composite restora-tion over the period of time due to the polymerisation contraction leading to an increased rate of secondary caries formation in composite resin restoration compared to the amalgam restoration (Leinfelder, 2000;Ziskind et al., 2007).
In an opposing note, replacement of composite restoration is frequently associated with pain and sensitivity, which is less likely observed in amalgam restoration (Advokaat, 1990;Naito, 2008). Various authors have reported the survival rates of amalgam; the mean survival time is 22.5 years, while modern amalgam can be manipulated such that the restoration can stay for 12 to 15 years of durability. 78% of amalgam restorations survive over ive years, 67% over ten years and 48% quite ifteen years (Kolker et al., 2005;Soares and Cavalheiro, 2010;Smales and Hawthorne, 1997). A 20 year old study done by Robinson has reported that the average longevity of amalgam was found to be approximately 10 years (Hickel and Manhart, 2001).
The limitations of this study include limited sample size and the time frame. The future scope of the study is to extend the data collection into a wider range of population and to analyze the frequency of amalgam restoration over other direct restorations and its survival analysis based on age and tooth surfaces.

CONCLUSION
Within the limitations, the mandibular premolars have predominantly restored surface was found to be disto-occlusal (DO), and less frequently Mesio-Occluso-Distal (MOD) surface that had undergone class 2 amalgam restoration. The amalgam, in terms of longevity, is superior to composite resin restorations. The amalgam should always be given the irst choice of preference if it does not concern esthetic appeal, especially in posterior teeth due to excel-lent load-bearing capacity and reduced incidence of marginal leakage and secondary caries formation.