Abstract
Background:
Dentinal hypersensitivity is a common disorder in dental practice, with existing treatments often offering only transient relief. Low-level laser therapy (LLLT) has emerged as a promising option owing to its prolonged pain-suppressing effects and growing patient acceptance.
Objective:
This study aimed to assess the immediate and sustained efficacy of LLLT, fluoride varnish, and desensitizing paste in treating dentinal hypersensitivity.
Materials and Methods:
A total of 120 participants were randomly assigned to three treatment groups: Group I (LLLT), Group II (fluoride varnish), and Group III (arginine calcium carbonate paste). Evaluation using the Visual Analogue Scale (VAS) and numerical rating scale (NRS) occurred immediately after the first application, at 1 week, after the second application, and at 15 days, 1 month, and 3 months. Clinical parameters, including plaque index (PI) and clinical attachment level (CAL), were assessed at baseline, 1 month, and 3 months.
Results:
Intergroup comparisons revealed a statistically significant difference at later time points (15 days, 1 month, and 3 months), with LLLT demonstrating superior efficacy in reducing dentinal hypersensitivity compared to the other two interventions. Intragroup comparisons for clinical parameters PI and CAL exhibited statistically significant differences. However, intergroup comparisons for both clinical parameters did not indicate any statistically significant differences.
Conclusion:
This study’s findings suggest that LLLT offers greater and sustained reduction in dentinal hypersensitivity over a 3-month period, outperforming sodium fluoride varnish and arginine calcium carbonate paste.
Keywords: Hypersensitivity, low-level laser therapy, pain assessment, visual analog scales
INTRODUCTION
Dentinal hypersensitivity is a common clinical problem, eliciting both physical discomfort and psychological distress in patients. Manifesting as a brief, intense pain triggered by various stimuli (e.g., thermal, evaporative, tactile, osmotic, or chemical), this condition arises from exposed dentin and cannot be classified under other dental defects or pathologies.[1]
Two primary theories (the hydrodynamic and neural theories) can be used to explain the mechanism behind dentinal hypersensitivity. These theories suggest that external stimuli induce fluid movement within dentinal tubules, leading to the stretching or compression of the pulp’s outer odontoblasts and their associated nerve terminals, resulting in pain.[2]
Numerous biomaterials and techniques have been used to manage dentin hypersensitivity, centered around either blocking dentinal tubules or chemically impeding pulpal nerves. Current regimens, administered both in-office by dentists and at-home through over-the-counter dentrifices, seek to alleviate immediate discomfort and offer enduring relief. Pioneering research endeavors focus on developing innovative materials and therapeutic strategies for addressing dentinal hypersensitivity comprehensively.[3]
Laser therapy has emerged as a preferred treatment for dentinal hypersensitivity owing to the increased acceptance by patients. In comparison to traditional desensitizing topical agents, lasers deliver faster and effective results, albeit at a higher cost.[4] Laser therapy not only partially seals dentinal tubules but also exerts analgesic effects and fosters pulp tropism. Low-level laser radiation demonstrates a wide-ranging impact on somatic pain, including hyperesthesia, quickly inducing an anesthetic effect.[5]
While previous studies highlighted the synergistic benefits of combining lasers with desensitizing agents, there is a lack of literature evidence assessing the standalone efficacy of low-level laser therapy (LLLT) versus desensitizing topical agents. Therefore, this study was performed to compare the effectiveness of LLLT, fluoride varnish, and desensitizing paste application in treating dentinal hypersensitivity.
MATERIALS AND METHODS
This clinical observational study, designed as a single-blinded investigation, focused on patients presenting with the primary complaint of dentinal hypersensitivity. The study was conducted over a period of 1 year and 6 months. The protocol was approved by the institutional ethical committee. Prior to the initiation of the study, the nature, potential risks, benefits, and objectives of the research were explained to each patient, and their informed written consent was obtained.
The study comprised 120 subjects presenting with the primary complaint of dentinal hypersensitivity. Employing randomized systematic sampling, the participants were assigned to one of three study groups:
Group I: LLLT
Group II: Sodium fluoride varnish
Group III: Arginine calcium carbonate paste.
The inclusion criteria encompassed individuals meeting the following criteria: (1) patients experiencing sensitivity attributed to mechanical, chemical, or thermal stimuli; (2) dentinal hypersensitivity manifesting in two or more teeth; and (3) the presence of dental conditions, including attrition, erosion, abrasion, and abfraction. Conversely, exclusion criteria were defined as follows: (1) individuals with dental pathologies such as caries, pulpitis, cracked enamel, and fractured teeth; (2) those with recent cervical restoration, orthodontic appliances, or periodontal surgery within the preceding 3 months; (3) pregnant or lactating women; and (4) patients currently using analgesic and anti-inflammatory medications.
After conducting oral prophylaxis for patients experiencing dentinal hypersensitivity, they were subsequently randomized into one of three study groups.
Group I (n = 40): In this cohort, patients underwent treatment with a low-level laser at 630–670 nm wavelength, delivering 100 mW/cm2 in contact mode with a 15 mW output power [Figure 1]. The laser beam was applied to dentinal surfaces in continuous mode for 160 s per tooth, using a uniform sweeping motion [Figure 2]. The participants were then recalled after 1 week.
Figure 1.
Laser armamentarium
Figure 2.
Laser application
Group II (n = 40): Individuals in this group received treatment with sodium fluoride varnish [Figure 3]. The varnish was applied with a disposable brush to the cervical region of hypersensitive teeth, following cotton roll isolation [Figure 4]. The patients were instructed to abstain from eating, drinking, or brushing immediately after varnish application and were recalled after 1 week.
Figure 3.
Sodium fluoride varnish armamentarium
Figure 4.
Sodium fluoride varnish application
Group III (n = 40): This cohort underwent treatment with arginine calcium carbonate desensitizing paste. The paste was applied in a pea-sized amount over the hypersensitive area of the tooth for 10 s [Figure 5]. The patients were advised against rinsing their mouths for 15 min after application to optimize clinical efficacy. They were then recalled after 1 week.
Figure 5.
Arginine calcium carbonate paste application
All patients underwent re-evaluation after 1 week, with subsequent re-application as needed. Follow-up reviews were conducted at 2 weeks, 1 month, and 3 months posttreatment.
The clinical parameters under evaluation encompassed the plaque index (PI), assessed at baseline, 1 month, and 3 months, and the clinical attachment level (CAL), determined by measuring the distance between the cemento-enamel junction and the base of the periodontal pocket, evaluated at baseline and 3 months [Figure 6].
Figure 6.
Determination of clinical attachment level
Assessment of dentinal hypersensitivity utilized both the Visual Analogue Scale (VAS) and the Numerical Rating Scale (NRS). On these scales, 0 indicated the absence of pain, and 10 denoted unbearable pain and discomfort experienced by the patient. To elicit hypersensitivity, the exposed radicular surface of the tooth was gently scraped by a periodontal probe or explorer (tactile stimulus) [Figure 7]. In addition, a jet of air was applied using a dental syringe at a distance of 1 cm for 5 s (evaporative stimulus) [Figure 8]. Subsequently, the patient’s response to these stimuli was recorded.
Figure 7.
Application of tactile stimuli
Figure 8.
Application of evaporative stimuli
Statistical analysis
In this study, the sample size was determined as 116, rounded up to 120 to avoid follow-up attrition. With an allocation of 40 individuals per group, maintaining a 1:1:1 ratio, the study was designed with a 95% confidence interval, 80% power, and an effect size of 0.80. The sample size calculation was performed using G*Power software, version 3.1.9.2 (Heinrich Heine University, Düsseldorf, North Rhine-Westphalia, Germany). Data analysis was carried out using IBM SPSS Statistics, version 20 (IBM Corp., Armonk, New York, USA). Various statistical methods, including descriptive statistics, paired t-tests, and repeated measures analyses of variance, were employed to comprehensively analyze the study data. For clear data presentation, bar charts and line diagrams were utilized.
RESULTS
Dentinal hypersensitivity was assessed among the three groups using the NRS, where 0 indicated the absence of pain, and 10 denoted unbearable pain and discomfort reported by the patient. Following the evaporative stimulus, at the early time points (baseline and after the first application), the mean scores for the three groups did not reveal any statistically significant differences (P = 0.91 and P = 0.30, respectively). However, at later time points (after the second application, 15 days posttreatment, 1-and 3-months posttreatment), a statistically significant difference in mean scores was observed [Table 1].
Table 1.
Intergroup comparison of numerical rating scale for evaporative and tactile stimuli
| Stimuli | Time points | Group I | Group II | Group III | P |
|---|---|---|---|---|---|
| Baseline | 6.65±1.001 | 6.70 ±1.09 | 6.75 ±1.17 | 0.91 | |
| After 1st application | 4.95 ±0.98 | 5.23±0.80 | 5.23±0.94 | 0.3 | |
| 1-week post-op | 3.78±0.76 | 4.23±0.80 | 4.15±0.83 | 0.03 | |
| Evaporative | After-2nd application | 2.83±0.74 | 3.23±0.80 | 3.15±0.83 | 0.04 |
| 15-days post-op | 1.80±0.51 | 3.13±0.80 | 2.93±0.82 | <0.001 | |
| 1-month post-op | 1.80±0.51 | 3.13±0.80 | 2.80±0.79 | <0.001 | |
| 3-months post-op | 1.91±0.51 | 3.10±0.70 | 2.75±0.74 | <0.001 | |
| Baseline | 5.53±0.96 | 5.78±1.07 | 5.80±1.11 | 0.43 | |
| After 1st application | 4.35±0.94 | 4.75±1.05 | 4.70 ±1.11 | 0.17 | |
| 1-week post-op | 3.35±0.94 | 3.75±1.05 | 3.78±1.02 | 0.11 | |
| Tactile | After-2nd application | 2.35±0.94 | 2.75±1.05 | 2.80±1.01 | 0.09 |
| 15-days post-op | 1.85±0.62 | 2.45±0.74 | 2.18±0.78 | <0.001 | |
| 1-month post-op | 1.85±0.62 | 2.45±0.74 | 2.18±0.78 | <0.001 | |
| 3-months post-op | 1.85 ±0.62 | 2.43±0.74 | 2.18±0.78 | <0.002 |
Subsequently, following the evaporative stimulus, a tactile stimulus was employed to elicit dentinal hypersensitivity, and patient responses were recorded based on the aforementioned NRS scale. At the early time points, no statistically significant differences were found when comparing mean scores between the three groups (P = 0.43, P = 0.17, P = 0.11, and P = 0.09, respectively). However, a statistically significant difference in mean scores emerged between the three groups at the later time points [Table 1].
When comparing the VAS scores among the three groups using both evaporative and tactile stimuli, no statistically significant differences were observed at baseline, after the first application, 1-week posttreatment, and after the second application: (P = 0.89, P = 0.33, P = 0.06, and P = 0.11, respectively) and (P = 0.43, P = 0.17, P = 0.11, and P = 0.09, respectively). However, the mean scores between the three groups exhibited a statistically significant difference at later time points, following both evaporative and tactile stimuli [Table 2].
Table 2.
Intergroup comparison of visual analog scale for evaporative and tactile stimuli
| Stimuli | Time points | Group I | Group II | Group III | P |
|---|---|---|---|---|---|
| Baseline | 6.65±1.001 | 6.75±1.17 | 6.75±1.17 | 0.89 | |
| After 1st application | 4.95±0.98 | 5.22±0.84 | 5.22±0.94 | 0.33 | |
| 1-week post-op | 3.77±0.76 | 4.15±0.83 | 4.15±0.83 | 0.06 | |
| Evaporative | After-2nd application | 2.82±0.74 | 3.15±0.83 | 3.15±0.83 | 0.11 |
| 15-days post-op | 1.80±0.51 | 2.92±0.82 | 2.92±0.82 | <0.001 | |
| 1-month post-op | 1.80±0.51 | 2.80±0.79 | 2.80±0.79 | <0.001 | |
| 3-months post-op | 1.80±0.51 | 2.80±0.79 | 2.80±0.79 | <0.001 | |
| baseline | 5.52 ±0.96 | 5.70±1.11 | 5.80±1.11 | 0.43 | |
| after 1st application | 4.35±0.94 | 4.60±1.02 | 4.70±1.11 | 0.17 | |
| 1-week post-op | 3.35±0.94 | 3.50±1.01 | 3.77±1.02 | 0.11 | |
| Tactile | After-2nd application | 2.35±0.94 | 2.50±0.78 | 2.80±1.01 | 0.09 |
| 15-days post-op | 1.85±0.62 | 2.07±1.08 | 2.17±0.78 | <0.01 | |
| 1-month post-op | 1.85±0.62 | 2.07±0.78 | 2.17±0.78 | <0.01 | |
| 3-months post-op | 1.85±0.62 | 2.07±0.78 | 2.17±0.78 | <0.01 |
In this study, we assessed two clinical parameters, i.e., the PI and CAL. The PI was evaluated and compared across the three groups at baseline, 1 month, and 3 months. The mean scores for Group I (3.16 ± 0.83, 2.76 ± 0.88, and 2.51 ± 0.61, respectively), Group II (2.76 ± 0.88, 1.60 ± 0.62, and 2.25 ± 0.72, respectively), and Group III (2.51 ± 0.61, 1.37 ± 0.40, and 1.87 ± 0.31, respectively) demonstrated no statistically significant differences at these time points [Table 3]. In addition, the CAL was scrutinized and compared among the three groups at baseline and 3 months postoperation. The mean scores at baseline and 3 months for Group I (2.03 ± 0.80 and 1.30 ± 0.46, respectively), Group II (2.00 ± 0.78 and 1.28 ± 0.45, respectively), and Group III (2.00 ± 0.81 and 1.33 ± 0.47, respectively) displayed no statistically significant differences [Table 3].
Table 3.
Intergroup comparison of clinical parameters plaque index and clinical attachment level
| Clinical parameters | Time points | Group I | Group II | Group III | P |
|---|---|---|---|---|---|
| baseline | 3.16±0.83 | 2.76±0.88 | 2.51±0.61 | 0.07 | |
| Plaque index | 1-month post-op | 2.07±0.72 | 1.60±0.62 | 1.37±0.40 | 0.06 |
| 3-months post-op | 2.51±0.76 | 2.25±0.72 | 1.87±0.31 | 0.06 | |
| Clinical attachment level | Baseline | 2.03±0.80 | 2.00±0.78 | 2.00±0.81 | 0.09 |
| 3-months post-op | 1.30±0.46 | 1.28±0.45 | 1.33±0.47 | 0.89 |
The intragroup analysis involved comparing mean sensitivity scores at different time points within each group, revealing noteworthy variations. In Group I, sensitivity exhibited a progressive decrease from a baseline of 6.65 ± 1.001 to 4.95 ± 0.986 after the initial application, followed by a further reduction to 3.78 ± 0.768 after 1 week, 2.83 ± 0.747 after the second application, and eventually stabilizing at 1.80 ± 0.516 after 15 days, 1 month, and 3 months. Similarly, Group II experienced a decline in sensitivity from 6.70 ± 1.091 at baseline to 5.23 ± 0.800 after initial application, subsequently dropping to 4.23 ± 0.800 after 1 week, 3.23 ± 0.800 after the second application, and ultimately reaching 3.10 ± 0.709 after 3 months. Group III demonstrated a comparable pattern, with sensitivity decreasing from 6.75 ± 1.171 at baseline to 5.23 ± 0.947 after the first application, further decreasing to 4.15 ± 0.834 after 1 week, 3.15 ± 0.834 after the second application, and stabilizing at 2.75 ± 0.742 after 3 months. Statistical analysis revealed a significant difference in mean scores within each group at the specified time points (P < 0.001) [Table 4].
Table 4.
Intragroup comparison of numerical rating scale for evaporative and tactile stimuli
| Evaporative stimuli | ||||||||
|---|---|---|---|---|---|---|---|---|
|
| ||||||||
| Group | Baseline | After 1st application | 1 week post-up | After 2nd application | 15 days post-op | 1-month post-op | 3-month post-op | P |
| I | 6.65±1.00 | 4.95±0.98 | 3.78±0.76 | 2.83±0.74 | 1.80±0.51 | 1.80±0.51 | 1.80±0.51 | |
| II | 6.70±1.09 | 5.23±0.80 | 4.23±0.80 | 3.23±0.80 | 3.13±0.68 | 3.13±0.68 | 3.10±0.70 | |
| III | 6.75±1.17 | 5.23±0.94 | 4.15±0.83 | 3.15±0.83 | 2.93±0.82 | 2.80±0.79 | 2.75±0.74 | <0.001 |
|
| ||||||||
| Tactile stimuli | ||||||||
|
| ||||||||
| I | 5.53±0.96 | 4.35±0.94 | 3.35±0.94 | 2.35±0.94 | 1.85±0.62 | 1.85±0.62 | 1.85±0.62 | |
| II | 5.78±1.07 | 4.75±1.05 | 3.75±1.05 | 2.75±1.05 | 2.45±0.74 | 2.45±0.74 | 2.43±0.74 | |
| III | 5.80±1.11 | 4.70±1.11 | 3.78±1.02 | 2.80±1.01 | 2.18±0.78 | 2.18±0.78 | 2.18±0.78 | <0.001 |
Intragroup comparison of mean scores, following the application of a tactile stimulus, revealed a notable trend. In Group I, sensitivity decreased from a baseline of 5.53 ± 0.960 to 4.35 ± 0.949 after the initial application. This reduction continued, reaching 3.35 ± 0.949 after 1 week, 2.35 ± 0.949 after the second application, and stabilizing at 1.85 ± 0.622 after 15 days, 1 month, and 3 months. Similarly, in Group II, sensitivity declined from 5.78 ± 1.074 at baseline to 4.75 ± 1.056 after the first application. This decline persisted, registering at 3.75 ± 1.056 after 1 week, 2.75 ± 1.056 after the second application, and ultimately reaching 2.43 ± 0.747 after 3 months. In Group III, sensitivity decreased from 5.80 ± 1.114 at baseline to 4.70 ± 1.114 after the first application. This reduction continued to 3.78 ± 1.025 after 1 week, 2.80 ± 1.018 after the second application, and stabilized at 2.18 ± 0.781 after 15 days, 1 month, and 3 months. The difference in the mean scores within Groups I, II, and III at the mentioned time point was found to be statistically significant (P < 0.001) [Table 4].
We conducted an intragroup analysis of mean scores assessed using the VAS. In Group I, sensitivity decreased from a baseline score of 6.65 ± 1.00 to 4.95 ± 0.98 after the initial application. Subsequently, it further decreased to 3.77 ± 0.76 after 1 week, 2.82 ± 0.74 after the second application, 1.80 ± 0.51 after 15 days, and remained at 1.80 ± 0.51 after both 1 and 3 months. In Group II, sensitivity decreased from 6.75 ± 1.17 at baseline to 5.22 ± 0.94 after the first application, followed by a reduction to 4.15 ± 0.83 after 1 week, 3.15 ± 0.83 after the second application, 2.92 ± 0.82 after 15 days, and stabilized at 2.80 ± 0.79 after both 1 and 3 months. Group III exhibited a similar pattern, with sensitivity decreasing from 6.75 ± 1.17 at baseline to 5.22 ± 0.94 after the first application, followed by reduction to 4.15 ± 0.83 after 1 week, 3.15 ± 0.83 after the second application, 2.92 ± 0.82 after 15 days, and stabilizing at 2.80 ± 0.79 after both 1 and 3 months. The observed differences in mean scores within Groups I, II, and III at the specified time points were statistically significant (P < 0.001) [Table 5].
Table 5.
Intragroup comparison of visual analog scale for evaporative and tactile stimuli
| Evaporative stimuli | ||||||||
|---|---|---|---|---|---|---|---|---|
|
| ||||||||
| Group | Baseline | After 1st application | 1 week post-up | After 2nd application | 15 days post-op | 1-month post-op | 3-month post-op | P |
| I | 6.65±1.00 | 4.95±0.98 | 3.77±0.76 | 2.82±0.74 | 1.80±0.51 | 1.80±0.51 | 1.80±0.51 | |
| II | 6.75 ±1.17 | 5.22±0.94 | 4.15±0.83 | 3.15±0.83 | 2.92±0.82 | 2.80±0.79 | 2.80±0.79 | |
| III | 6.75±1.17 | 5.22±0.94 | 4.15±0.83 | 3.15±0.83 | 2.92±0.82 | 2.80±0.79 | 2.80±0.79 | <0.001 |
|
| ||||||||
| Tactile stimuli | ||||||||
|
| ||||||||
| I | 5.52±0.96 | 4.35±0.94 | 3.35±0.94 | 2.34±0.94 | 1.85±0.62 | 1.85±0.62 | 1.85±0.62 | |
| II | 5.70±1.11 | 4.60±1.02 | 3.50±1.01 | 2.50±0.78 | 2.07±0.78 | 2.07±0.78 | 2.07±0.78 | |
| III | 5.80±1.11 | 4.70±1.11 | 3.77±1.02 | 2.80±1.01 | 2.17±0.78 | 2.17±0.78 | 2.17±0.78 | <0.001 |
We conducted an intragroup analysis of mean scores assessed by the VAS following tactile stimulus. In Group I, sensitivity decreased from a baseline score of 5.52 ± 0.96 to 4.35 ± 0.94 after the initial application. Subsequently, it further decreased to 3.35 ± 0.94 after 1 week, 2.34 ± 0.94 after the second application, 1.85 ± 0.62 after 15 days, and remained at 1.85 ± 0.62 after both 1 and 3 months. In Group II, sensitivity decreased from 5.70 ± 1.11 at baseline to 4.60 ± 1.02 after the first application, followed by a reduction to 3.50 ± 1.01 after 1 week, 2.50 ± 0.78 after the second application, 2.07 ± 0.78 after 15 days, and stabilized at 2.07 ± 0.78 after both 1 and 3 months. Group III exhibited a similar pattern, with sensitivity decreasing from 5.80 ± 1.11 at baseline to 4.70 ± 1.11 after the first application, followed by a reduction to 3.77 ± 1.02 after 1 week, 2.80 ± 1.01 after the second application, 2.17 ± 0.78 after 15 days, and stabilizing at 2.17 ± 0.78 after both 1 and 3 months. The observed differences in mean scores within Groups I, II, and III at the specified time points were statistically significant (P < 0.001) [Table 5].
A thorough examination of PI and CAL within each group was conducted. In Group I, the PI exhibited a notable decrease from 3.16 ± 0.83 at baseline to 2.07 ± 0.72 1-month posttreatment, followed by a subsequent increase to 2.51 ± 0.76 at 3 months posttreatment. In Group II, a reduction in PI was observed from 2.76 ± 0.88 at baseline to 1.60 ± 0.62 1-month posttreatment, with a subsequent increase to 2.25 ± 0.72 at 3 months. Group III experienced a decrease in PI from 2.51 ± 0.61–1.37 ± 0.40 1-month posttreatment, followed by an increase to 1.87 ± 0.31 at 3 months. Statistical analysis revealed a significant difference in mean scores within each group at the specified time points (P < 0.001) [Table 6].
Table 6.
Intragroup comparison of plaque index and clinical attachment level
| Plaque index | ||||
|---|---|---|---|---|
|
| ||||
| Group | Baseline | 1-month post-op | 3-month post-op | P |
| I | 3.16±0.83 | 2.07±0.72 | 2.51±0.76 | |
| II | 2.76±0.88 | 1.60±0.62 | 2.25±0.72 | <0.001 |
| III | 2.51±0.61 | 1.37±0.40 | 1.87±0.31 | |
|
| ||||
| Clinical attachment level | ||||
|
| ||||
| Group | Baseline | 3-month post-op | P | |
| I | 2.00±0.78 | 1.33±0.47 | ||
| II | 1.30±0.46 | 1.28±0.45 | <0.001 | |
| III | 2.00±0.81 | 2.03±0.80 | ||
Upon evaluating the CAL, noteworthy trends emerged within each group. In Group I, the CAL exhibited a reduction from 2.00 ± 0.78 at baseline to 1.33 ± 0.47 at 3 months posttreatment. In Group II, a subtle decrease was observed from 1.30 ± 0.46 to 1.28 ± 0.45. Conversely, in Group III, a marginal increase in CAL was noted, increasing from 2.00 ± 0.81 at baseline to 2.03 ± 0.80 at 3 months posttreatment. Statistical analysis underscored the significance of these changes, with the mean scores within each group at the specified time points being found to be statistically significant (P < 0.001) [Table 6].
DISCUSSION
Dentinal hypersensitivity is a prevalent clinical problem, marked by an intensified reaction to external stimuli applied to the exposed dentin. It manifests as brief, acute pain triggered by stimuli such as temperature changes, evaporation, touch, osmotic shifts, or chemical exposure.[2] Remarkably, this discomfort cannot be attributed to any other dental defect or pathology. Despite dentinal hypersensitivity being recognized and studied for more than a century, the precise etiological factors contributing to its occurrence remain elusive.
Over the years, numerous factors have been postulated as potential contributors to dentinal hypersensitivity. Types of tooth wear (including attrition, erosion, abrasion, and abfraction), periodontal conditions (such as gingival recession and developmental anomalies), and external factors (such as age and vigorous brushing) are believed to facilitate the apical migration of the gingival margin. This process exposes dentin and, over time, results in the development of dentinal hypersensitivity.[6]
Various theories have been proposed to explain the mechanisms behind dentinal hypersensitivity. Among them, the hydrodynamic theory has garnered significant support and acceptance. According to this theory, dentinal hypersensitivity arises when stimuli applied to dentin displace the fluid within the dentinal tubules, either inward or outward, triggering the activation of resident baroreceptors.[7] Viewing dentinal hypersensitivity through the lens of this theory suggests that an optimal treatment approach would involve interventions capable of diminishing fluid flow within the dentinal tubules or possessing the potential to impede pulpal nerve responses.
In addressing dentinal hypersensitivity, many treatment strategies have been proposed, each yielding varying degrees of success. Desensitizing and analgesic agents have emerged as prominent choices, categorized as either at-home or in-office therapies based on their mode of administration. At-home options include toothpastes, mouthwashes, and chewing gums designed for desensitization. Conversely, in-office solutions involve the application of gels, solutions, varnishes, resin sealers, glass ionomers, and dentin adhesives to treat hypersensitivity.[3] Moreover, recently, the introduction of lasers has sparked significant interest among clinicians and researchers as a potential treatment avenue for dentinal hypersensitivity.
Within the wide range of available treatment options, this study aimed to assess and compare the efficacy of sodium fluoride varnish, arginine calcium carbonate paste, and LLLT in managing dentinal hypersensitivity.
Sodium fluoride varnish primarily operates by occluding or narrowing dentinal tubules to reduce dentinal hypersensitivity. Notably, its advantages include immediate and straightforward application.[8] However, this treatment has a limitation owing to the elimination of the generated precipitate through activities such as tooth brushing, saliva exposure, and chemical factors such as meals, acidic beverages, and dental biofilm-created acids. Consequently, the sustained efficacy of sodium fluoride may gradually diminish.[9] Another challenge is the small size of the crystals, necessitating repeated applications of fluoride varnish to maintain its therapeutic effect.
Kleinberg[10] has outlined the mechanism of arginine calcium carbonate paste as follows. Positively charged arginine is attracted to the negatively charged dentin surface, facilitating the deep penetration of calcium carbonate into the dentin. The presence of arginine and calcium carbonate within dentin tubules creates an alkaline environment, promoting the deposition and occlusion of endogenous calcium and phosphate ions. A distinctive advantage of arginine calcium carbonate paste is in the natural presence of its two key components (arginine and calcium) in saliva. This combination works synergistically to accelerate the innate occlusive processes. The paste deposits a mineral resembling dentin, rich in calcium and phosphate, both within the dentin tubules and as a protective layer on the dentin surface. This proarginin desensitizing dentifrice is the recommended agent for prompt relief from dentin hypersensitivity.
The emergence of lasers in dentistry has resulted in transformative breakthroughs, especially in addressing dentinal hypersensitivity, where promising outcomes have been observed. While the utilization of lasers has demonstrated significant advantages, some studies have underscored a notable drawback – specifically, the generation of heat, which has the potential to cause pulpal damage and necrosis.[11] However, low-power lasers, unlike high-power lasers, do not generate heat; instead, they activate the normal cellular functions. This activation occurs through a change in the electrical potential of the cell membrane, triggering the Na+/K+ ATPase pumps, enhancing adenosine triphosphate synthesis, and conferring analgesic, potentially anti-inflammatory, and biomodulation benefits to the cells.[12] Consequently, this process successfully alleviates pain associated with dentinal hypersensitivity. Owing to its long-lasting action compared to other desensitizing agents, LLLT is regarded as a promising option for treating dentinal hypersensitivity.
The aim of this study was to assess the immediate and sustained efficacy of LLLT, fluoride varnish, and desensitizing paste after re-application in the treatment of dentinal hypersensitivity. A total of 120 patients, presenting with hypersensitivity as their primary concern, were selected based on evaluations involving evaporative and tactile stimuli. These stimuli were chosen for their objectivity and widespread use in assessing therapeutic substances in dentine hypersensitivity research. After applying the stimuli, patient responses were recorded using both the NRS and VAS. There are several methods for assessing pain, including various instruments and scales. However, the most commonly used scales in clinical research and pain surveys are the VAS, NRS, verbal rating scale (VRS), and facial pain scale.[13] In this study, we opted to use the VAS and NRS because they are more sensitive than the VRS. The patients were randomly assigned to three groups, each comprising forty individuals. Group I received LLLT, Group II received sodium fluoride varnish, and Group III received arginine calcium carbonate desensitizing paste. Dentinal hypersensitivity scores were recorded immediately after application and subsequently at intervals of 1 week, after the second application, at 15 days, 1 month, and 3 months posttreatment.
Both intergroup and intragroup comparisons were conducted to identify trends in the evaluation of the three treatment modalities. Following the application of evaporative and tactile stimuli, intergroup comparisons among the three groups demonstrated a consistent pattern when assessed using both the NRS and VAS. Specifically, the mean scores exhibited no statistically significant differences at early time points (immediately after application, 1 week after application, and after the second application). However, a statistically significant difference emerged when comparing mean scores between the groups at later time points (15 days, 1 month, and 3 months). Intergroup comparisons between the three groups revealed that the mean scores exhibited a gradual and statistically significant decrease in the laser therapy group. In addition, the arginine calcium carbonate group demonstrated a reduction in mean scores compared to the sodium fluoride group. This trend aligns with the findings of a randomized clinical trial conducted by Uraz et al.[14] in 2013, wherein in-office treatment with arginine calcium carbonate paste led to a significant reduction in sensitivity compared to sodium fluoride gel. Notably, this reduction persisted during the 28-day follow-up period.
Intragroup comparisons within each of the three treatment groups were conducted, revealing statistically significant differences in responses to evaporative and tactile stimuli recorded on both the NRS and VAS. This pattern persisted from the baseline assessment through the 3-month follow-up period. These intragroup findings align with the results of a study by Praveen et al.[15] conducted in 2018. Their randomized, controlled, double-blinded clinical study concluded that both topical desensitizer and LLLT were effective in reducing dentinal hypersensitivity. Of note, the study suggested that LLLT demonstrated a comparatively higher effectiveness at the various time intervals studied.
Beyond the primary etiological concern, various factors can exert influence on dentinal hypersensitivity. Therefore, our study encompassed the assessment of the PI at baseline, 1 month, and 3 months, alongside measurements of the CAL at baseline and 3 months. The results demonstrated a noteworthy enhancement in both the PI and CAL during the follow-up period. In terms of the PI, intragroup comparisons revealed a statistically significant difference when the mean scores were compared at baseline, 1 month, and 3 months within each of the three groups (P < 0.001). Conversely, intergroup comparisons indicated no statistically significant difference in mean PI scores among Groups I, II, and III at baseline, 1 month, and 3 months (P = 0.07, P = 0.06, and P = 0.06, respectively).
Regarding the CAL, intragroup comparisons unveiled a statistically significant difference when the mean scores within the three groups were compared at baseline and after 3 months (P < 0.001). In contrast, intergroup comparisons indicated no statistical significance when the mean CAL scores were compared among Groups I, II, and III at baseline and after 3 months (P = 0.07, P = 0.06, and P = 0.06, respectively).
It is important to acknowledge the limitations of our study, including a relatively small sample size and a short duration. Evaluating the efficacy of a treatment modality, particularly for conditions such as dentinal hypersensitivity, necessitates a comprehensive understanding of its sustained effectiveness over time. The 3-month duration may be insufficient in providing a definitive conclusion on the enduring potential of a specific treatment modality.
CONCLUSION
Within the limitations of this study, the following conclusions can be made:
This study demonstrated the superiority of LLLT in managing dentinal hypersensitivity when compared to sodium fluoride varnish and arginine calcium carbonate paste, especially over a 3-month period
Over the years, a major roadblock in the management of dentinal hypersensitivity was the fact that the available treatments often offered only transient relief. This study showed that LLLT offers enduring efficacy, which is particularly evident at later time points compared to other desensitizing agents. This positions LLLT as a promising long-term treatment modality for dentinal hypersensitivity.
Further longitudinal studies and randomized clinical trials with large sample size should be conducted to evaluate and compare the efficacy of low-level laser, sodium fluoride varnish, and arginine calcium carbonate paste in treating dentinal hypersensitivity.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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