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The use of dental composite is increasing owing to patient’s demand for tooth-colored restorations [1]. The properties of composite resins have improved significantly in the last few years [2]; however, inherent limitation owing to the shallow depth of cure of resin composite necessitated the utilization of an incremental technique during the placement of composites in cavities deeper than 2 mm [3, 4]. This is done to ensure that light from curing devices can reach the deeper parts of the restoration leading to an adequate degree of conversion of monomers into polymers [5]. This is very critical to the longevity of the restorations since it was reported previously that under-cured resin composites are more likely to fail, necessitating their replacement [6-8].
In order to streamline the clinical procedure of deeper cavities, new formulations were developed which allow for the filling of cavities up to 5 mm deep in a single increment. These materials are known as Bulk-Fill (BF) resin composites [9]; and have different chemistries compared to conventional resin composites [10]. BF materials tend to have special fillers with more translucency values in order to allow deeper penetration of light [11]. Also, higher light-cure irradiance values are required in order to deliver enough energy into the bottom of the cavity enabling the polymerization of the material. Even though, irradiance values between 400 and 600 mW/cm2 can be considered adequate for curing conventional resin composite [12], BF formulations require irradiance values exceeding 1,000 mW/cm2 in order to ensure an adequate degree of conversion [13]. Further, new and more sensitive photoinitiators are used to ensure adequate initiation and propagation of the polymerization reaction [9].
Understanding key differences in chemistry and application techniques between conventional and BF resin composite is very important to clinicians. Since these materials are relatively new, not all practicing dentists might be aware of these differences. Choosing the correct material, the proper application technique and the light curing device with adequate irradiance value are paramount in ensuring a successful restoration. Furthermore, proper utilization data must be known in order to provide relevant recommendations for daily practice, especially for recently graduating dentists.
Thus, the aim of the current study was to assess the knowledge and utilization of dental practitioners of bulk-fill resin composite materials. Establishing a baseline knowledge status can allow decision-makers and university professors to cope with workplace practices as well as community demand.
2. MATERIALS AND METHODS 2.1. Ethics StatementThe questionnaire and methodology for this study were approved by the Research Ethics Committee of the Faculty of Dentistry at King Abdulaziz University (Ethics approval number: 112-10-19 in April, 3rd, 2019). Further, a confidentiality disclosure was included in the introductory portion of the online questionnaire. The study was conducted between November 2019 and March 2020.
2.2. Target GroupThe target audience for the survey was dental practitioners in Saudi Arabia. The questionnaire was sent electronically via social media applications (Twitter, Instagram, Telegram, and Whatsapp) based on local databases targeting governmental universities and hospitals as well as private schools and practices. The selection was random based on sending the link over the social media outlets.
2.3. Online Questionnaire DesignThe online questionnaire was designed using Google Forms software (Google LLC, Mountain View, California, United States) and was divided into sections: 1) demographic data [8 questions], 2) knowledge about BF resin composite properties and technique [16 questions], and 3) utilization of BF resin composite in daily practice [6 questions]. After the demographic information part of the survey, two conditional questions were included in the survey at the beginning of the knowledge and utilization sections (Fig. 1). Based on answering these two questions, the participants were categorized into 3 groups: 1) participants without knowledge, 2) participants with knowledge but no utilization, or 3) participants with knowledge and utilization.
2.4. Study ParametersFor each parameter within the demographic data, each answer level was compared to others to determine trends and differences within the sample. For each question within the knowledge section, the proportion of participants with the correct answer was determined. Each correct answer was given a score, and the total knowledge scale (KS; out of 25 points) was determined for each participant to estimate the level of knowledge concerning BF resin composite. A KS ≥ 50% was considered a satisfactory knowledge level. For the utilization section, proportions of answers for each question were compared. Furthermore, the effect of demographic data on knowledge and the effect of knowledge on utilization were also investigated.
2.5. Statistical AnalysisAll Data were collected, tabulated and subjected to statistical analysis. All analyses were performed using SPSS Version 20 (SPSS Inc., Chicago, Illinois, USA). Qualitative categorical variables were described by frequencies and percentages. Data were presented, when appropriate, by the Pareto method. Quantitative variables were described by the mean and standard deviation.
Shapiro-Wilk test of normality was used to test the normality hypothesis of the knowledge scale. Z test was applied for the difference between two proportions. Chi-squared test was used for the assessment of the relation between two categorical variables. Post-hoc analysis using adjusted residuals and Bonferroni correction were used for further analysis of the effect of employment status if the chi-squared test was significant. A 0.05 significance level was used for all tests. During analysis, some answer options were grouped together in order to maintain the statistical assumptions of the test.
3. RESULTS 3.1. Demographic DataA total of 195 responses were received for the online survey; of which 12 were excluded (10 participants were interns and 2 responses had missing data; Fig. 1). Consequently, the final number of participants in this survey was 183 practitioners. Fifty-one participants did not have previous knowledge of BF composites, and 132 had some knowledge; of which 76 practitioners had used BF composite at some point. The general characteristics of the cohort are included in Table 1. Most participants were general practitioners (95%), graduated from King Abdulaziz University (57%) during the last 10 years (91%), and with less than 5 years of experience (86%).
Fig. (1). A flowchart showing the different questions of the survey and number of participants at each stage depending on the answers for the conditional questions (outlined with rectangles). Questions 1 and 17 were conditional inquiries which were used to categorize participants according to their knowledge and utilization of BF resin composites. Asterisks indicate questions with multiple answers; the rest of the questions were in multiple choice format.
Fig. (2). A bar graph showing overall proportions of participants regarding knowledge and utilization. Different letters indicate significant differences (p ≤ 0.05). Overall, only 9.84% of the participants (n = 183) had satisfactory knowledge regarding bulk-fill composites (scoring ≥ 50% on the used knowledge score).
Table 1.Summary of demographic data. Asterisks indicate statistically higher response compared to other options within the same question (p ≤ 0.05).
Category Response Percent Significance Between Responses P-Value for Z-test Gender Male 49.7 No 0.92 Female 50.3 Nationality Saudi* 97.8 Yes < 0.001 Non-Saudi 2.2 City/region Central region 9.8 Yes < 0.001 Western region* 80.9 Eastern region 4.9 Northern region 1.1 Southern region 3.3 Graduation University Taiba University 3.8 Yes < 0.001 King Saud University 4.4 King Khalid University 1.6 Um Al Qura University 2.2 Alfarabi College 4.4 King Abdulaziz University* 57.4 Ibn Sina College 9.8 Batterjee College 2.7 Imam University 1.6 Other 12 Year of Graduation Before 1980 0 Yes < 0.001 1981 - 1990 0.6 1991 - 2000 2.7 2001 - 2010 6.0 2011 – 2019* 90.7 Current Position General practitioner* 94.5 Yes < 0.001 Specialist 3.8 Consultant 1.1 Other 0.6 Years of Experience < 5* 86.3 Yes < 0.001 5 - 9 10.9 10 - 15 1.1 >15 1.1 Employer Unemployed 44.8 No 0.054 Government 31.7 Private 23.5Only 76 out of 183 (41.5%) participants have the knowledge and utilize BF composite. Fig. (2) illustrates the proportions of participants in regards to knowledge and utilization. There was no significant difference between females (18%) and males (9.9%) regarding knowledge of BF materials (p = 0.172). The knowledge scale (KS), normalized on a 100 point, with a score below 50% was considered unsatisfactory. The KS data followed a normal distribution and showed that only 18 out of 123 (9.84%) participants had a satisfactory knowledge level. KS was not influenced by gender, years of experience or employment status (p> 0.05).
Table 2 shows the proportions of answers for each question in the knowledge section of the survey along with the results of statistical tests. The data is presented both out of the total participants of the survey (n = 183; percentages might not add to 100%) and out of the participants who responded yes to Q1 (n = 132; percentages will add up to 100%). Lectures were the main source of information (Fig. 3), SDR was the most commonly reported BF material by participants, and core build-up was the most frequent application reported (Fig. 4).
Considering the difference between BF and conventional composites, only a significantly low proportion (7%) chose “photoinitiators” (p< 0.001). A similarly low proportion (7%) chose “degree of conversion/depth of cure” (p< 0.001). In addition, BF materials were considered easier to use compared to conventional formulations (p< 0.001), being not suitable for anterior restorations (6%), and do not require a special cavity preparation (62%) or an incremental approach (70%).
Regarding the minimum irradiance level in mW/cm2 for light cure used for BF resin composites, 300 - 600, 601 - 900, and 901 - 1200 mW/cm2 were the ranges commonly chosen with no statistical significance between the choices. (p> 0.05; Fig. 5). For conventional composites, however, 901 - 1200, 300 - 600, and 601 - 900 were the ranges chosen with no statistically significant difference between the choices (p> 0.05).
Table 2.Statistical comparisons for each question of the knowledge section of the survey according to answers.
Question Answer (Abbreviation) Out of Total Participants
1Percentages out of the total survey participants. Percentages might not add up to 100%
2Percentages out of participants who responded yes to Q1 (participants with knowledge about bulk-fill composites). Percentages will add up to 100%.
Fig. (3). A bar graph showing data for sources mentioned by the participants for information regarding bulk-fill materials. Different letters indicate significant differences (p ≤ 0.05).
Fig. (4). A bar graph showing data for applications mentioned by the participants for bulk-fill materials. Different letters indicate significant differences (p ≤ 0.05).
Fig. (5). A bar graph showing data for minimum irradiance levels mentioned by the participants for bulk-fill materials. Different letters indicate significant differences (p ≤ 0.05).
Table 3.Statistical comparisons for each question of the utilization section of the survey according to answers.
Question Answer (Abbreviation) Out of Total Participants
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