Abstract
Purpose The purpose of this follow-up proof-of-concept study was to determine the efficacy of a revised calculus disruption solution in facilitating the removal of both supragingival and subgingival calculus in-vivo, as measured by time, difficulty, and pressure required to remove supragingival and subgingival calculus.
Methods Patients from a dental school in Minnesota were recruited to participate in a randomized, split-mouth, cross sectional proof-of-concept study comparing time, difficulty and pressure used with hand instrumentation alone compared to the use of a calculus disruption solution and hand instrumentation. Quadrants were randomized to either treatment or control group. Descriptive and inferential statistics were used to analyze the amount of time used. A paired Student’s t-test was used to analyze the primary outcome (α = 0.05). Post-treatment questionnaires were completed by the investigator and participants to score the perceived difficulty and pressure required to remove calculus.
Results Thirty participants completed the study. An average of 3.1 minutes less time was needed to remove supra and subgingival calculus in the treatment quadrants although this was not statistically significant (p=0.5757). The secondary outcomes, the investigator and participants’ perceived difficulty and pressure used for calculus removal showed either no difference, or slight improvements in the treatment quadrants. Overall, the product was well tolerated by participants.
Conclusion Quadrants treated with a calculus disruption solution, required slightly less time than control quadrants for calculus removal with hand instruments although the difference was not statistically significant. Reformulation to increase the viscosity of the solution may improve efficacy. Future studies should include a larger sample size, using multiple operators, and a double-blind study design.
INTRODUCTION
The complete removal of supragingival and subgingival calculus, the mineralized form of dental biofilm, is a key step in achieving periodontal health.1 The standard of care for calculus removal includes the use of a combination of hand and ultrasonic instrumentation techniques, and/or coronal polishing.1 Hand instrumentation can put physical strain on the clinician’s body through the use of repetitive movements and prolonged gripping, which have been suggested as a contributing factor to musculoskeletal disorders (MSDs) in dental health care personnel (DHCP).2–4 A 2018 systematic review examined MSD prevalence rates in DHCPs from 41 studies, demonstrating an average pooled MSD prevalence of 78%.3 These findings were similar to an earlier review conducted which identified a MSD prevalence in dentists and dental hygienists ranging from 64% to 93%.5 In an effort to reduce the risk of MSDs, researchers have explored a variety of interventions including more ergonomic dental operatory equipment and instruments. Increasing the diameter and decreasing the weight of scaling instruments has been shown to decrease muscle activity and pinch force pressure used during hand instrumentation.6 Other ergonomic studies found that the use of modified scaling techniques, increased self-awareness and self-assessment of ergonomics, and the use of magnification loupes can also help reduce a DHCP’s risk of MSDs.7–9 Despite equipment and ergonomic modification being commonly presented as effective ways to prevent MSDs, there is a lack of rigor and conclusive evidence establishing links between preventive interventions for MSDs, highlighting the need for further research in this area.2
Another relevant topic is the renewed attention to the infection control practices related to aerosol-generating procedures routinely conducted within dental practices during the COVID-19 pandemic. Infection control is one of the professional responsibilities of the dental hygienist.10 Aerosol-generating procedures are known to carry infectious pathogens which can be transmitted to dental patients via airborne transmission, or through contact with inanimate environmental surfaces.11 In laboratory tests, infectious microbes have been shown to persist in aerosols for many hours.11 Strategies for reducing the amount of time spent on calculus deposit removal and the need for performing aerosol-generating procedures, including ultrasonic scaling, have been studied previously.12
A calculus removal product that reduces time spent, difficulty of removal, and pressure used by DHCPs could help to reduce operator fatigue and the pinch forces that contribute to MSDs. A product designed to ease the removal of supragingival and subgingival calculus could also result in a more comfortable patient experience due to less time spent in the dental chair and the reduced pressure used for the removal of calculus. A validated product that aids in the manual removal of supragingival and subgingival calculus may reduce the number of aerosol-generating procedures being performed, and thus, could act as an alternative to the use of an ultrasonic scaler when appropriate. In a previous proof-of-concept study on a calculus disruption solution (EXP-955; 3M Oral Care Solutions Division, St. Paul, MN), ease of removal of supragingival calculus was studied.12 Supragingival calculus is more easily removed as it is visible to the clinician and attached to smooth enamel surfaces above the gingival margin. Conversely, subgingival calculus is inherently more difficult to remove due to its attachment to the porous cementum which retains calculus. Clinicians must rely on tactile exploration or a specialized dental endoscope in order to detect subgingival deposits.1 It is important to remove both supragingival and subgingival deposits as they elicit an inflammatory response in the soft tissues.1 Researchers from the first proof of concept study indicated the need for further investigations to test a calculus disruption solution on subgingival deposits.12
Feedback on the first iteration of this calculus disruptive solution was provided by the investigator and considered by the sponsor to create a revised solution (EXP-971; 3M Oral Care Solutions Division, St. Paul, MN). The new iteration of the solution went through comprehensive in-vitro testing on extracted human teeth, indicating that the revised solution may reduce the time, difficulty, and pressure used in calculus removal. Varying concentrations of solution components were explored to help define the most effective ratios during in-vitro testing. Risk assessment and biocompatibility testing was performed, and it was demonstrated that the revised solution was biologically safe for its intended use.
The purpose of this follow-up proof-of-concept study was to determine the efficacy of a revised calculus disruption solution in facilitating the removal of both supragingival and subgingival calculus in-vivo, as measured by time, difficulty, and pressure required to remove supragingival and subgingival calculus. The objectives of the study were 1) to determine if there was statistically significant difference in time spent to remove all calculus in control quadrants where hand instrumentation alone was used compared to time spent to remove calculus in treatment quadrants where the calculus disruption solution was used as an adjunct to hand instrumentation, 2) to determine if there was a difference in the difficulty to remove all calculus in control versus treatment quadrants, and 3) to determine if there was a difference in the amount of pressure used to remove all calculus in control vs treatment quadrants.
METHODS
The University of Minnesota Institutional Review Board (IRB) approved this study and assigned it IRB ID: STUDY00003723: A RCT on Efficacy of Medical-Device to Facilitate Removal of Supra/Subgingival Dental Calculus. The clinical trial was conducted at a single site and a randomized, split-mouth study design was used. The term “investigator” was used for both examiner and operator in this study. The investigator had 12 years’ experience as a clinical dental hygienist, educator, and researcher. It was not possible to blind the investigator to the treatment quadrant due to the reaction created by the prototype solution when placed on the teeth. For this reason, the investigator was able to carry out all study roles independently. The manufacturer educated the investigator on proper prototype solution storage, preparation, and application prior to study recruitment.
Sample Population
Recruitment advertisements were posted throughout the University of Minnesota School of Dentistry and 92 interested volunteers were screened by telephone. Exclusion criteria included being under the age of 18, having had a prophylaxis, scaling and root planing, or periodontal maintenance treatment in the past year, being pregnant or lactating, and requiring prophylactic antibiotics prior to routine dental treatment. Adults lacking the ability to provide informed consent, employees of the sponsor or students enrolled in a dental-related program were also excluded. Following the telephone screening, 50 participants attended in-person screening appointments and 32 were eligible for enrollment in the study. Because the proof-of-concept study was intended to provide estimates of effect size and variance for use in future studies, no statistical justification of the sample size was completed. Participants were enrolled and scheduled for the treatment appointment if they met the inclusion criteria (presenting in good health, having at least 5 teeth in each study quadrant, and a minimum score of 2 on the Oral Calculus Index - Simplified (OCI-S; Score Range 0-3)13 in each study quadrant (Table I).
Oral Calculus Index-Simplified (OCI-S) for quadrant scoring
Procedures
After completion of the telephone screening, participants who qualified for the in-person screening visit were scheduled to determine eligibility to participate. After participants signed the informed consent forms, the investigator then completed a medical and dental history, and screened for inclusion and exclusion criteria. An intra- and extra-oral examination was performed to ensure no major oral health concerns were present. Participants were enrolled and scheduled for the treatment appointment if they met the inclusion criteria and provided informed consent.
The investigator then completed a tactile evaluation of the whole mouth with an 11/12 explorer (Hu-Friedy MFG. Co., LLC Chicago, IL, USA), as well as a visual evaluation using a mouth mirror, compressed air and transillumination to determine the presence of supra and subgingival calculus deposits. The investigator then assigned one OCI-S score for each quadrant, for a total of four scores (Table I). It is important to note that the investigator did not assign scores based on individual teeth, which was the intent of the original OCI-S. Participants were enrolled if two analogous quadrants on opposing sides of the mouth were present and each quadrant had an OCI-S minimum score of 2. The investigator chose to study quadrants that were comparable in the number of teeth present, as well as OCI-S scores. This design allowed the participants to serve as their own control. Pre-treatment intraoral photographs of the study quadrants were taken with a digital camera. After enrollment and screening, participants were scheduled to return for the treatment appointment within thirty days. At each treatment appointment, the investigator reviewed the medical history, and reconfirmed inclusion and exclusion criteria. The investigator also reminded participants of the post-treatment questionnaire items prior to beginning calculus removal in an effort to ensure participants remained alert and attentive during the treatment appointment.
Block randomization was used to execute the split-mouth study design by assigning quadrants to the control and treatment group. In order to avoid inadvertently getting any calculus disruption solution in the control quadrant, the investigator always began by removing calculus in the control quadrant first, prior to applying the solution in the experimental quadrant. Several cassettes filled with new instruments including a scaler (Montana Jack; Paradise Dental Technologies Inc, Missoula, MT, USA), and curettes (11/12 and 13/14 Gracey, 13/14 Columbia, and 17/18 McCall; Hu-Friedy Co., LLC Chicago, IL, USA) were used in the study. Instruments were sharpened prior to each appointment, and as needed during treatment.
A plastic test stick was used to confirm instrument sharpness prior to the commencement of calculus removal in each quadrant. Instruments were sharpened again before the investigator began the treatment quadrant when needed. A digital timer was started prior to calculus removal in both control and treatment quadrants. Time to mix and apply the investigational solution was included in the timing of the treatment quadrant. The solution required a two-step application. The first step required mixing of two parts, which was accomplished by connecting two syringes with a syringe spacer and pushing the plungers back and forth to mix the two parts to form solution 1. The syringes were then disconnected, and a dispensing tip was added to the syringe holding the two parts which had been combined to prepare solution 1. That was then applied to the supra and subgingival calculus in treatment quadrants. The application of solution 1 was immediately followed by the application of solution 2, which did not require any mixing prior to its use. Hand instrumentation began immediately after application of the solutions. Once the investigator had confirmed that all calculus, and stain had been removed, the timer was stopped. Deposit removal was confirmed by the investigator using a tactile and visual evaluation during the hand instrumentation of each quadrant and again at completion. An 11/12 explorer (Hu- Friedy Co., LLC; Chicago, IL, USA), mouth mirror, compressed air and transillumination were used to confirm deposit removal. If any deposits remained, the investigator re-instrumented the area until complete calculus removal was confirmed. Evaluation times were included in the calculus removal time for both the control and treatment quadrants.
The investigator captured tooth-level measures of both difficultly of calculus removal as well as pressure required to remove calculus using a 3-point scale (1-Easy, 2-Moderate, 3-Hard) during instrumentation. The tooth-level measures would later be averaged at the participant-quadrant level to create single scores for each of these measures. Any residual calculus disruption solution was rinsed off prior to taking post-treatment intraoral photographs for comparison of soft and hard tissue in both quadrants. Following the intraoral photographs, each participant was asked to complete the post-treatment questionnaire. The investigator also completed a post-treatment questionnaire for each subject. At the conclusion of the session, participants were offered another appointment to complete the oral prophylaxis.
Outcome Measures and Statistical Analysis
The primary outcome studied was the time (minutes), needed to remove calculus in the control quadrant using hand instrumentation exclusively, compared to the treatment quadrant using hand instrumentation combined with the calculus disruption solution. Secondary outcomes were collected from the investigator and participant questionnaires. Variables included the difficulty, and pressure used to remove the calculus, as well as the subjective experience and viewpoints from the investigator and participant perspectives. A paired Student’s t-test was used for the primary outcome results, comparing the time to removel calculus using hand instrumentation in the control versus treatment quadrants (α=0.05). Statistical analyses for the primary outcome (time) were performed using a statistical software program (SAS 9.4; SAS Institute, Cary, NC, USA). Means and standard deviations were calculated for difficulty, and pressure used to remove the calculus. Categorical secondary variables were summarized in frequency distributions. No statistical analysis was performed on the secondary outcome variables. Given the nature of this proof-of-concept study, some post-hoc analyses were performed to explore potential relationships between participant demographics and the presence of tenacious calculus. All data was recorded on either paper case report forms (CRFs) and then manually entered into an electronic data capture (eDC) system, or they were recorded directly in the eDC system. The investigator was trained on the use of the eDC system prior to opening enrollment.
RESULTS
Thirty-two participants met the inclusion criteria and consented to participate in this study; one participant was lost to follow-up and one withdrew because they required local anesthesia. Thirty participants, ranging from 18-83 years with a mean age of 43.2 years, completed the study. Participants’ mean average years since their previous oral prophylaxis or scaling and root planing procedure was 3.6 years. Complete demographic information is shown in Table II.
Participant demographics (n=30)
The mean time for calculus removal in the control quadrant was 33.4 minutes compared to the treatment quadrant mean time of 30.3 minutes, a reduction of 3.10 minutes when using the calculus disruption solution. However, this reduction in time needed for calculus removal was not statistically significant (p=0.5757) (Table III).
Average time to remove calculus in control vs treatment quadrants
Differences were identified in the mean amount of time needed for calculus removal when maxillary quadrants were compared to mandibular quadrants. Nine participants (30%) were selected for complete calculus removal in the maxillary quadrants. Average maxillary calculus removal time in control quadrants was 24.7 minutes as compared to 33.7 minutes in the treatment quadrants representing a 9-minute increase in time spent in the maxillary treatment quadrants (p=0.3981) (Table III).
Of the 21 participants who had mandibular quadrants scaled, the average time for control quadrants was 37.1 minutes compared to 28.9 minutes in the treatment quadrants representing a time savings of 8.2 minutes in quadrants where the calculus disruption solution was used (Table III). In treatment quadrants identified with tenacious calculus, an overall time savings of 5.4 minutes was shown (p=0.4041). Maxillary treatment quadrants took longer than the maxillary control quadrants while mandibular treatment quadrants took less time than the corresponding control quadrant (Table III).
Subjective feedback from the investigator included noted obstacles that may have affected the instrumentation time including crowding, uncontrollable tongue and lips, lingual retainer, and other. The “other” category included anxious participants needing multiple breaks, an abundance of saliva and/or blood requiring frequent suctioning and/or rinsing, and participants requesting that the investigator stop to allow for rinsing and/or spitting. The investigator noted that the calculus disruption solution was “too flowable” in a majority of the participants (n=28, 93%) and described it as easily transferrable without dripping in a little more than a third of the participants (n=11, 37%). General comments and further investigator feedback are shown in Table IV.
Summary of investigator responses
Secondary outcomes included the difficulty of calculus removal, and the amount of pressure used to remove calculus as perceived by the investigator. Single scores for each of the secondary outcomes were determined by averaging the investigator ratings of each individual tooth in both the control and treatment quadrants. These average scores showed the control and treatment quadrants having the same difficulty of removal score 1.5 (between Easy and Moderate). The average pressure score for the control quadrant was 1.7, compared to the average of 1.5 in the treatment quadrants (Table V).
Average difficulty and pressure scores
Participant feedback indicated that over half (n=17, 57%) noticed a time savings in the treatment quadrant and thought that the control quadrant took longer to complete. Nearly half (n=14, 47%) stated that they could tell a difference from one side compared to the other and perceived that there was less pressure used in the control quadrant. A few participants (n=5, 16.7%) indicated a low level of discomfort with the placement of the investigational solution. Reasons for discomfort included the product dripping down the throat, worry about swallowing the product during application, and discomfort with the use of the syringe tip subgingivally. One participant reported dentinal hypersensitivity with placement of the treatment solution that was quickly resolved following the application. All other participants tolerated the solution well, and no soft tissue differences were noted when comparing before and after intraoral photographs of control and treatment quadrants. Participant feedback is shown in Table VI.
Summary of participant responses
General comments from the investigator:
● Product dripped on participant’s face and lips during application
● In areas of tenacious calculus, I did not notice a difference in difficulty of removal, even after reapplication of the product.
● Teeth on the treatment side seemed smoother after cleaning when compared to control.
● Product label was sticking to the patient’s lip, making application difficult.
● The patient needed many breaks during application as they said the product was running down the back of their throat. This increased the time taken in the treatment quadrant.
● Difficulty with application of the product due to strong lip/tongue pull.
● Product works best when the patient is able to stay open for application and calculus removal, as it stays on the teeth longer and has time to work. This participant was able to stay open the whole time, and the product worked well!
● Chemical reaction with the product can make it hard to see during application and hand instrumentation.
● Use caution when using on patients with a history of dentinal hypersensitivity.
● Patient had lots of saliva which may have rinsed the product off and contributed to the product not working as well. Reapplied product.
● Participant had trouble keeping open, so I had to reapply
DISCUSSION
A product that could soften calculus, resulting in a more efficient and comfortable experience during the removal of hard deposits could benefit both the patient and the clinician. Less time, physical effort, and repetitive motions used to remove calculus could contribute to addressing the issue of MSDs in DHCPs. Since the initial proof-of-concept study was conducted in 2020,12 there are still no other products on the market to be compared to this experimental solution. Contrary to the findings of the previous study that explored the efficacy of the first iteration of this solution on supragingival calculus only, there was no significant difference in time spent to remove calculus supragingivally and subgingivally in this study.12 Although the length of appointment scheduled for dental hygiene care, including oral prophylaxis, is patient-specific, preventive dental appointments are most commonly scheduled for 45 to 90 minutes per patient. Within the parameters of that appointment, the dental hygienist must include the standards of care of patient assessment, dental hygiene diagnosis, dental hygiene care planning, implementation, evaluation, and documentation.10 A time savings of 3.1 minutes, while not statistically significant, may hold some clinical benefit. A few minutes saved during the implementation phase of treatment could allow for time to complete other important aspects of care such as collaboration and communication with the patient, infection control, and documentation, to name a few. While this is a proof-of-concept study, a benefit-cost analysis should be considered by clinicians interested in using such a product in clinical practice. While the product may save some time during hand instrumentation, the cost, and time spent educating the patient on the product should be considered by the clinician on a patient-specific level.
Maxillary treatment quadrants may have taken longer than mandibular treatment quadrants due to the low viscosity of the product causing it to drip off the maxillary teeth, outlier participants with tenacious calculus, or because more participants who self-identified as tobacco users were included in this group. All of the participants who identified as tobacco users (n=3) were in the group selected for maxillary treatment and control quadrants. Additionally, of the tobacco users, two were identified by the investigator as having tenacious calculus. Another participant who denied tobacco use was also identified as having tenacious calculus. Post-hoc analyses revealed that there was an overall time savings of 5.4 minutes (p=0.4041) in treatment quadrants when the results of the participants identified as having tenacious calculus by the investigator were removed from the data set. This could indicate that the solution may not be as effective in tenacious calculus removal. Dated, yet relevant, studies show a statistically significant correlation between patients who smoked tobacco, and the amount of supragingival and subgingival calculus present.14,15 Tobacco smokers are also at an increased risk for more advanced periodontal disease, which can complicate nonsurgical instrumentation.1 Ideally, future iterations of the calculus removal solution would be effective in a variety of oral conditions regardless of calculus tenacity or tobacco use status.
Selected comments from the participants:
● Tasted minty like toothpaste. Label stuck to my lip when it was being applied.
● Seemed slippery on my teeth when the product was first applied. Product side feels smoother to my tongue after the cleaning.
● Felt cool on application. Side with the product used feels smoother immediately after and up until the end of the appointment.
● Felt like I had to spit more when the product was used.
● Product caused a little bit of numbness on my gums, but I liked that effect.
● Only thing that caused discomfort was the syringe tip, not the solution. It was hard for me not to swallow or wait to spit when I felt dripping.
● The side with the treatment seemed faster, and like bigger pieces were coming off.
● Packaging looks like a needle, which made me anxious and nervous at first.
● I was concerned about swallowing the product during application.
● Didn’t like that the product was runny and dripped down my throat. Should be more gel-like.
● Heard more noise during cleaning when product was not used.
● Really liked it. Much smoother/faster process when product is used.
● Product caused tooth sensitivity.
● Product made cleaning easier and faster.
Results of the secondary efficacy outcomes show either no difference, or slight perceived improvements associated where the calculus disruption solution was used. A double-blind study design should be considered for future studies using a placebo solution to create a similar experience for both investigator and participant when applied to the teeth. This could help to reduce investigator and participant bias and help to control for the time spent applying the investigational solution. A larger sample size is necessary to further explore and determine whether the differences in efficacy in the maxillary arches as compared to the mandibular arches was circumstantial. The small sample size of this proof-of-concept study may have also contributed to the heavily weighted outliers, which could have disproportionately affected the results. It is important to note that this study was not powered to determine statistical significance, but rather to explore feasibility and to inform effect size for future study power calculations. Adding an additional study team member would be beneficial to future studies in order to conduct the timing of complete calculus removal. This would blind the investigator conducting the hand instrumentation to the time spent to achieve complete calculus removal in both quadrants. Also, using additional operators who would complete calculus removal in future studies would provide a wider variety of opinions and feedback on the solution, rather than that of one individual.
As the standard of care for complete calculus removal also includes adjunctive therapies such as ultrasonic instrumentation, it may be beneficial to redesign the study protocol to include the use of ultrasonic as well as hand instruments in the treatment and control groups when appropriate. An effective calculus disruptive solution could result in a shorter period of time needed for the aerosol-generating procedures needed to achieve complete calculus removal. This could ultimately decrease the amount of infectious aerosols being produced in dental hygiene practice. With the recently renewed concern for the prevention of transmission of infectious organisms in the dental office associated with aerosol-generating procedures, a solution to aid in calculus removal may be valued by the dental hygienist and dental patients. Lastly, as no periodontal probing depths or periodontal health statuses were assessed in this study, future investigations should consider studying a calculus disruptive solution in both shallow and deep periodontal pockets as well as in participants with a range of periodontal health statuses.
CONCLUSION
Quadrants treated with a calculus disruption solution required slightly less time than control quadrants for calculus removal with hand instruments, although the difference was not statistically significant. Results of secondary outcomes from the investigator and participant questionnaires showed either no difference, or slight perceived improvements associated with use the calculus disruption solution in test quadrants. Overall, the product was well tolerated by participants. Reformulations to increase the viscosity of the solution may improve efficacy. Future studies should include a larger sample size, using multiple operators, and a double-blind study design.
Footnotes
NDHRA priority area, Client level: Occupational health care (new therapies and prevention modalities).
DISCLOSURE
Funding for this study and the prototype solution (EXP-971) was provided by 3M, Oral Care Solutions Division, St. Paul, Minnesota, USA.
- Received January 26, 2022.
- Accepted July 28, 2022.
- Copyright © 2023 The American Dental Hygienists’ Association
