Toothpastes containing potassium nitrate alone versus potassium nitrate combined with aluminum lactate in reducing dentin hypersensitivity: a randomized controlled trial

Abstract

Objective

Dentin hypersensitivity (DH) is a common clinical condition characterized by transient, sharp pain arising from exposed dentinal tubules in response to external stimuli. The aim of this study was to evaluate and compare the efficacy of two toothpaste formulations: one containing 5% potassium nitrate alone and another combining 5% potassium nitrate with 2.18% aluminum lactate.

Materials and methods

This was a parallel-group, randomized, double-blind, negative-control trial with 127 participants. Participants were randomly assigned to three groups (two test and one placebo). The Dentin Sensitivity Index (DSI) was assessed under tactile and air stimulation at baseline, immediately after brushing, and at 2 weeks, 4 weeks, 4 weeks plus 24 h, and 8 weeks.

Results

Compared with baseline, both test groups showed statistically significant reductions in DSI for both tactile and air stimulation at all time points immediately after use. From 2 weeks onward, the DSI of both test groups was significantly lower than that of the placebo group at all evaluated time points. Furthermore, the toothpaste containing 5% potassium nitrate combined with 2.18% aluminum lactate exhibited a greater effect than the potassium nitrate alone at specific time points: 4 weeks for air stimulation, 4 weeks plus 24 h for tactile stimulation, and 8 weeks for both types of stimulation.

Conclusions

Both toothpaste formulations—5% potassium nitrate alone and 5% potassium nitrate combined with 2.18% aluminum lactate—demonstrated significant efficacy in reducing dentin hypersensitivity, with the combination showing greater improvement at several time points.

Clinical trial registration

Trial registration: ISRCTN80733222.

Introduction

Dentin hypersensitivity (DH) is a common clinical condition characterized by transient, sharp pain arising from exposed dentinal tubules in response to external stimuli, such as thermal, evaporative, tactile, electrical, osmotic, or chemical factors. [1] This pain is explained by the hydrodynamic theory, which posits that gingival recession or loss of enamel/cementum exposes dentinal tubules, allowing external stimuli to induce rapid fluid movement within the tubules. This fluid shift activates pulpal nerve endings, resulting in sharp pain. [2, 3] Although typically short-lived, DH can cause considerable discomfort and adversely impact patients’ quality of life, interfering with eating, drinking, and oral hygiene maintenance. [4–6]

The reported prevalence of DH varies widely across regions and studies, with lifetime incidence rates ranging from 3% to 98%. [7] DH is most commonly reported in adults, with a peak prevalence between 30 and 40 years of age and a slight predilection for females over males. [7, 8] A national survey in China found that 32.1% of individuals aged 20–69 years were affected by DH. [9]

Management of DH typically involves professional dental clinic treatment and the use of desensitizing toothpaste. Toothpastes containing active ingredients for relieving hypersensitivity are convenient, cost-effective, and widely accessible to patients. [1, 10] These formulations primarily act through two mechanisms: (1) chemical desensitization of nerve responses and (2) physical occlusion of dentinal tubules. [2, 11] Accordingly, desensitizing agents can be broadly categorized based on their modes of action. [2] Potassium nitrate, which reduces DH by desensitizing pulpal nerves, has garnered considerable attention for its proven efficacy. [12–15] In contrast, aluminum lactate alleviates DH through a physical mechanism that promotes dentinal tubule occlusion. [16–18] It interacts with phosphate ions in saliva to form aluminum phosphate, which deposits on the surface of dentinal tubules, narrowing or occluding them. This process occurs even at neutral pH and is enhanced by the presence of phosphate ions, thereby reducing DH. [16–18] Although strontium salts are commonly used in Western countries, aluminum lactate is preferred in Asia due to its safety and regulatory acceptance, making it a practical choice for desensitizing toothpaste. [16]

Despite the widespread availability of desensitizing toothpastes, head‑to‑head evidence directly comparing formulations—particularly potassium nitrate alone versus its combination with aluminum lactate—remains limited. Previous clinical trials, including our randomized controlled study in Korea [19], have demonstrated the efficacy of the combination of potassium nitrate and aluminum lactate compared with placebo. However, whether this combination and potassium nitrate alone are similarly effective in Chinese populations has not been fully established. The aim of this study was to evaluate and compare their efficacy in Chinese participants, addressing practical questions such as the time course of effect (immediate vs. sustained) and stimulus‑specific responses (e.g., tactile vs. evaporative), to provide actionable guidance for clinicians. This study was conducted as a feasibility-oriented clinical investigation to generate population-specific evidence in Chinese participants, rather than to assume inherent biological differences between populations. Prior randomized controlled trials (RCTs) [11] and reviews [20] highlight both the promise of combination approaches and the heterogeneity of methods and endpoints, underscoring the need for standardized, comparative trials.

Given the widespread use of desensitizing toothpastes and the limited directly comparative evidence, this study aimed to address key gaps in the literature. Specifically, we evaluated and compared the immediate and sustained efficacy of toothpastes containing 5% potassium nitrate alone versus 5% potassium nitrate combined with 2.18% aluminum lactate for dentin hypersensitivity, with responses assessed under both tactile and air-blast stimuli across multiple time points. The null hypothesis of this study was that there would be no difference in dentin hypersensitivity reduction among the tested toothpaste formulations.

Materials and methods

The clinical trial was conducted in accordance with the Chinese standard for evaluating the efficacy of desensitizing toothpastes (WS/T 326.4-2010). According to these guidelines, efficacy must be demonstrated using two types of stimuli—tactile and air-blast—and is defined as a statistically significant reduction in sensitivity indices compared with the placebo group, with at least one index showing an improvement of 15% or more from baseline. The following procedures were implemented in compliance with WS/T 326.4-2010 requirements.

This randomized, double-blind, parallel, negative-control clinical trial was designed to evaluate the long-term efficacy of toothpastes (containing 5% potassium nitrate alone or combined with 2.18% aluminum lactate) at baseline, immediate, 2, 4, and 8 weeks time points, and to assess the persistence of effect by comparing baseline and 4 weeks responses as well as outcomes at 4 weeks plus 24 h, against a placebo toothpaste. The primary outcome was the difference in effectiveness among the three toothpaste types in reducing DH in response to tactile and air stimulation at these time points. This clinical trial was approved by the Ethics Committee of the Affiliated Stomatological Hospital of Chongqing Medical University (ethical review number 2022 Ethics Review (042)). This study was registered in a clinical trial registry (ISRCTN80733222).

Participants

Details of the trial were explained to 127 healthy adults residing in China, who provided written informed consent and met the following criteria:

Inclusion criteria

Participants were eligible if they:

1. Were aged 18–65 years and in good general health;

2. Could attend all scheduled examinations during the 8-week study period;

3. Were not pregnant or breastfeeding (for female participants);

4. Had at least one dentin-sensitive tooth with cervical or gingival recession, sensitive to tactile stimulation at 10–50 g or responding to air stimulation with a score ≥ 2;

5. Had no history of allergy to toothpastes, oral care products, or their ingredients;

6. Were willing to sign an informed consent form.

Exclusion criteria

Participants were excluded if they:

1. Had severe systemic or chronic diseases;

2. Had severe dental, periodontal, or mucosal diseases;

3. Had a history of allergy to the test products;

4. Had advanced periodontal disease or had undergone periodontal treatment within the past year;

5. Had tooth mobility of grade 1 or higher in DH-affected teeth;

6. Had teeth with extensive restorations, suspected chronic pulpitis, dental caries, enamel cracks, or teeth serving as abutments for removable prostheses;

7. Were taking anticonvulsants, antihistamines, antidepressants, sedatives, tranquilizers, or anti-inflammatory drugs;

8. Had participated in desensitizing toothpaste studies within the past 3 months, regularly used desensitizing toothpastes, or were currently enrolled in other clinical trials.

Randomization and grouping

After the baseline examination, eligible healthy adult volunteers were enrolled. Participants were then assigned using stratified randomization with parallel assignment. Stratification was based on the maximum baseline Schiff sensitivity score of the two selected test teeth, ensuring balance in baseline sensitivity severity across groups, as this factor strongly influences post-treatment outcomes. Within each stratum, participants were randomly allocated in equal numbers to the test toothpaste groups or the placebo group, further stratified by sex.

Test products

All toothpastes were prepared by Lion Corporation (Tokyo, Japan). To ensure blinding and minimize bias, all the products were carefully matched in appearance, flavor, and packaging. Participants in Test Group 1 used toothpaste containing 5% potassium nitrate alone; those in Test Group 2 used toothpaste containing 5% potassium nitrate combined with 2.18% aluminum lactate; and participants in the placebo group used toothpaste with the same base formulation as the test products, consisting of commonly used ingredients in standard toothpastes, but without potassium nitrate or aluminum lactate. Owing to proprietary considerations, the full formulation details of the tested toothpastes are not disclosed. However, all formulations were based on commonly used ingredients in conventional dentifrices, and the active components are described above.

Methodology

Examination

Assessments were conducted at seven time points: screening phase, baseline, immediately after brushing, 2 weeks, 4 weeks, 4 weeks plus 24 h, and 8 weeks.

All participants were instructed to refrain from using any oral hygiene products for 4 h before the initial screening examination and to avoid eating and drinking for 2 h prior to the examination. Intraoral examinations included Dentin Sensitivity Index (DSI) assessments via tactile and air stimulation.

After the initial examination, participants underwent a 2-week washout period, during which they were provided with a washout toothpaste (identical to the placebo) and a commercially available manual toothbrush (Systema Regular Toothbrush; Lion Corporation, China). They were instructed to brush their teeth twice daily (once in the morning and once in the evening) for 2 min, using an amount of toothpaste equivalent to the length of the brush head (approximately 1 g), and to record the start time of each brushing session. Post-brushing rinsing behavior was not strictly controlled, as the study design aimed to reflect real-world usage conditions.

Following the washout period, a baseline examination was performed, and participants were assigned to one of the three groups based on the results. Prior to this examination, participants refrained from using oral hygiene products for 4 h and from eating and drinking for 2 h.

Participants were provided with an 8-week supply of toothpaste corresponding to their assigned group (test or placebo). For the immediate effects assessment, the assigned toothpaste was applied to the participants’ teeth, and DSI was evaluated 60 s later. Participants brushed their teeth with the assigned toothpaste and toothbrushes for 8 weeks, following the same method as during the washout period. Evaluations at 2, 4, and 8 weeks were conducted to assess both immediate effects and benefits of continued use.

Additionally, all participants used the washout toothpaste, which had the same formulation as the placebo product (without potassium nitrate or aluminum lactate), for 1 day after the 4 weeks’ examination, and their DSI was re-evaluated 24 h later (i.e., 4 weeks plus 24 h). A comparison between the evaluations at 4 weeks and 4 weeks plus 24 h evaluations was designed to assess the lasting effect of the toothpaste. This additional time point was included to evaluate the persistence of the desensitizing effect after temporary discontinuation, reflecting real-world usage conditions.

DSI assessment

DSI was evaluated according to the industry standard for assessing the efficacy of desensitizing toothpastes in China (WS/T 326.4-2010), using two test methods: tactile and air stimulus assessments. Details of these procedures are described below.

- Tactile stimulus assessment: A Yeaple electronic pressure probe [21] (Model 200 A Electronic Force-Sensing Probe; Jojen Technologies LLC, Monroe, NY, USA) was used to quantitatively measure the force (g) applied to the dentin surface. The probe was applied to the dentin area of the sensitive tooth, starting at 10 g and increasing in 10-g increments until the participant reported discomfort, at which point the pressure was recorded.

- Air stimulus assessment: A dental unit air gun was used to apply a 1-s air stimulus from 1 cm away from the dentin surface of the sensitive tooth, and the participant’s response was observed. During this assessment, the air compressor pressure was set to 60 ± 5 p.s.i, and the air-blast temperature was maintained at 19–21 °C. Cotton rolls were used to isolate adjacent teeth to improve measurement accuracy. Scores were evaluated using the Schiff cold air sensitivity scale, based on the participant’s reaction: 0 = no response from the tooth or participant; 1 =  response without a request to discontinue the stimulus; 2 = response accompanied by a request to stop or move the stimulus; 3 = painful reaction with an immediate request to halt the stimulus. [22]

Sample size estimation

The primary outcome was the difference in mean DSI change for each stimulus from baseline to the end of the follow-up period. Based on previous studies, the expected baseline mean DSI for air stimulation was 2.1 ± 0.8 in both test and placebo groups. The expected mean DSI at follow-up was 1.20 ± 0.7 in the test group and 1.60 ± 0.8 in the placebo group, with mean changes from baseline of 0.90 ± 0.6 and 0.50 ± 0.50, respectively. Using an unpaired t-test, assuming an α-error of 0.05 and an expected dropout rate of 15%, a minimum of 35 participants per group were required to achieve 80% statistical power.

The study was adequately powered ( > 80%) to demonstrate the superiority of the test toothpastes over the placebo for DSI, assuming a mean difference of 1.8 between the two groups immediately after application, and a common standard deviation of 13 (based on previous studies). Approximately 108 participants (36 per group) were required for this. To account for an anticipated dropout rate of up to 15% before completing the 8-week study, approximately 42 participants per group (126 total) were planned for randomization.

Statistical analysis

Data were analyzed using SPSS Statistics (Version 22.0; IBM Corp., Armonk, NY, USA). Baseline characteristics of participants were analyzed using descriptive statistics for continuous variables and χ² tests for categorical variables. All statistical analyses were two-sided, with a significance level (α) set at 0.05; p values < 0.05 were considered statistically significant. Differences among groups at each time point were compared using one-way ANOVA followed by Tukey-Kramer post hoc tests. Within-group comparisons across time points, including baseline, were performed using repeated measures ANOVA. χ² tests were used to analyze categorical variables.

Results

Participant demographics and baseline data

After the baseline examination, 127 eligible participants were enrolled based on the inclusion and exclusion criteria, 120 of whom completed the entire 8-week study. Seven participants dropped out, and their data were excluded from statistical analysis. Reasons for withdrawal were unrelated to the study products, and no adverse events attributed to the test toothpastes were observed in any participants.

Basic participant information is shown in Table 1. No statistically significant differences in the mean age or sex distribution were observed between the placebo and test groups.

Table 1.

Participant demographics

Groups	Placebo group	Test Group 1	Test Group 2	Total	p value
Sex					> 0.05
Female	22 (55%)	20 (50%)	22 (55%)	64 (53%)
Male	18 (45%)	20 (50%)	18 (45%)	56 (47%)
Total	40	40	40	120
Age					> 0.05
Mean	49.5 ± 8.6	49.7 ± 10.6	49.8 ± 10.2	49.6 ± 9.8
Minimum	28	26	22	22
Maximum	63	68	66	68

Baseline DSI status

Statistical analysis revealed no significant differences in mean baseline DSI among the three groups (Table 2). Fig. 1.

Table 2.

DSI for All Groups at Baseline

DSI†	Placebo group	Test Group 1	Test Group 2	p value
Tactile Stimulus (Probing Pressure (g))	12.63 ± 6.32	12.75 ± 2.76	12.50 ± 2.53	> 0.05
Air Stimulus (Schiff Index)	2.31 ± 0.31	2.39 ± 0.37	2.33 ± 0.37	> 0.05

†DSI Dentin Sensitivity Index

Fig. 1. Participant flow through the study.

Simplified flow diagram of participant allocation and follow-up in this feasibility-oriented randomized clinical study.

Immediate effects and benefits of continued use

DSI for each stimulus in all groups at baseline, immediately after brushing, 2 weeks, 4 weeks, and 8 weeks are shown in Table 3 and Fig. 2. In addition, the mean changes in DSI from baseline for each test group are presented in Table 4.

Table 3.

DSI of tactile and air stimulus for all groups at baseline, immediately after brushing, 2 Weeks, 4 Weeks, 8 Weeks

DSI†	Groups	Baseline	Immediately After Brushing	2 Weeks	4 Weeks	8 Weeks
Tactile Stimulus (Probing Pressure (g))	Placebo group	12.63 ± 6.32	13.13 ± 2.93	15.63 ± 4.26	17.75 ± 4.23	19.88 ± 4.46
	Test Group 1	12.75 ± 2.76	17.38 ± 3.75 **	19.75 ± 5.06 **	22.88 ± 3.18 **	26.88 ± 4.48 **
	Test Group 2	12.50 ± 2.53	19.13 ± 5.65 **	20.13 ± 5.61 **	24.88 ± 5.60 **	30.13 ± 4.16 **
Air Stimulus (Schiff Index)	Placebo group	2.31 ± 0.31	1.98 ± 0.53	2.08 ± 0.37	1.99 ± 0.24	1.85 ± 0.30
	Test Group 1	2.39 ± 0.37	1.96 ± 0.47 **	1.88 ± 0.33 **	1.75 ± 0.28 **	1.56 ± 0.44 **
	Test Group 2	2.33 ± 0.37	1.95 ± 0.34 **	1.79 ± 0.35 **	1.58 ± 0.40 **	1.31 ± 0.45 **

**: Statistically significant difference from baseline (p < 0.01).

†DSI Dentin Sensitivity Index

Fig. 2. Dentin Sensitivity Index of all groups during the 8-week study period.

a Tactile stimulus and (b) air stimulus assessed at baseline, immediately after brushing, 2 weeks, 4 weeks, and 8 weeks.

Table 4.

Percentage changes in DSI for tactile and air stimuli from baseline in each test group at immediately after brushing, 2 Weeks, 4 Weeks, 8 Weeks

DSI†	Groups	Immediately After Brushing	2 Weeks	4 Weeks	8 Weeks
Tactile Stimulus	Test Group 1	36.31%	54.90%	79.45%	110.82%
	Test Group 2	53.04%	61.04%	99.04%	141.04%
Air Stimulus	Test Group 1	17.99%	21.34%	26.78%	34.73%
	Test Group 2	16.31%	23.18%	32.19%	43.78%

†DSI Dentin Sensitivity Index

Tactile stimulus

Immediately after brushing and at 2, 4, and 8 weeks, both test groups exhibited significantly higher average probing pressures than the placebo group (p < 0.01). Furthermore, Test Group 2 showed a significantly higher average probing pressure than Test Group 1 at 8 weeks (p < 0.01). At all measurement points, the percentage changes from baseline in DSI for tactile stimulus in each test group exceeded 15%.

Air stimulus

At 2, 4, and 8 weeks, both test groups had significantly lower mean Schiff indices than the placebo group (p < 0.05). Immediately after brushing, both test groups showed lower mean Schiff indices than the placebo group, but the differences were not statistically significant. Additionally, Test Group 2 exhibited a significantly lower mean Schiff index than Test Group 1 at 4 and 8 weeks (p < 0.05). Across all time points, DSI for air stimulus showed percentage changes from baseline exceeding 15% in each test group.

Anti-dentin hypersensitivity lasting effect test

DSI for each stimulus in all groups at baseline, 4 weeks, and 4 weeks plus 24 h are shown in Table 5 and Fig. 3. In addition, the mean changes in DSI from baseline for each test group are presented in Table 6.

Table 5.

DSI of Tactile and Air Stimulus for All Groups at Baseline, 4 Weeks, 4 Weeks plus 24 h.

DSI†	Groups	Baseline	4 Weeks	4 Weeks plus 24 h
Tactile Stimulus (Probing Pressure (g))	Placebo group	12.63 ± 6.32	17.75 ± 4.23	19.13 ± 4.22
	Test Group 1	12.75 ± 2.76	22.88 ± 3.18 **	24.63 ± 3.82 **
	Test Group 2	12.50 ± 2.53	24.88 ± 5.60 **	27.63 ± 5.14 **
Air Stimulus (Schiff Index)	Placebo group	2.31 ± 0.31	1.99 ± 0.24	1.88 ± 0.32
	Test Group 1	2.39 ± 0.37	1.75 ± 0.28 **	1.58 ± 0.21 **
	Test Group 2	2.33 ± 0.37	1.58 ± 0.40 **	1.52 ± 0.41 **

**: Statistically significant difference from baseline (p < 0.01).

†DSI Dentin Sensitivity Index

Fig. 3. Dentin Sensitivity Index of all groups in the lasting-effect evaluation.

a Tactile stimulus and (b) air stimulus assessed at baseline, 4 weeks, and 4 weeks plus 24 hours.

Table 6.

Percentage Changes in DSI for Tactile and Air Stimuli from Baseline in Each Test Group at 4 Weeks, 4 Weeks plus 24 h.

DSI†	Groups	4 Weeks	4 Weeks plus 24 h
Tactile Stimulus	Test Group 1	79.45%	93.18%
	Test Group 2	99.04%	121.04%
Air Stimulus	Test Group 1	26.78%	33.89%
	Test Group 2	32.19%	34.76%

†DSI Dentin Sensitivity Index

Tactile stimulus

At 4 weeks and 4 weeks plus 24 h, both test groups had significantly higher mean probing pressures than the placebo group (p < 0.001). Test Group 2 exhibited a significantly higher mean probing pressure than Test Group 1 at 4weeks plus 24 h (p < 0.01). The percentage changes from baseline in average probing pressure were 15% or more for both test groups at 4 weeks and 4 weeks plus 24 h.

Air stimulus

At 4 weeks and 4 weeks plus 24 , both test groups showed significantly lower mean Schiff indices than the placebo group (p < 0.001). Furthermore, at 4 weeks, Test Group 2 had a significantly lower mean Schiff index than Test Group 1 (p < 0.01). At all measurement points, the percentage changes from baseline in mean Schiff index exceeded 15% in both test groups.

Discussion

This study demonstrated that both toothpaste formulations significantly reduced dentin hypersensitivity compared with placebo, with the combination of potassium nitrate and aluminum lactate showing greater efficacy at several time points.

The immediate desensitizing effect was observed only for tactile stimulation. From 2 weeks onward, both test toothpastes demonstrated significant desensitizing effects compared with the placebo for both DSI measures. After 4 weeks of use, the combination toothpaste began to show greater efficacy than the potassium nitrate-only formulation—first for air stimulation at 4 weeks, and for both tactile and air stimuli at 8 weeks, with statistically significant differences. Furthermore, after 4 weeks of continuous use, the desensitizing effect persisted for at least 24 hours even when the placebo toothpaste was used, and for tactile stimulation, the combination toothpaste maintained superior effectiveness compared with 5% potassium nitrate alone formulation. At all time points, both test groups exhibited improvements exceeding 15% from baseline for both DSI measures, meeting the effectiveness criteria defined by the Chinese standard: WS/T 326.4-2010.

The immediate improvement in tactile sensitivity after a single application may be attributable to the rapid action of potassium nitrate in modulating nerve excitability, leading to a temporary reduction in pain perception. In contrast, tubule occlusion is generally considered a slower mechanism that contributes to sustained desensitizing effects with continued use. Potassium nitrate is widely recognized to reduce dentin hypersensitivity by depolarizing nerve endings and inhibiting pain transmission. [16, 23] Tubule occlusion is a well-established mechanism for reducing dentin hypersensitivity by limiting fluid movement within dentinal tubules. [24, 25] These distinct mechanisms likely contributed to the superior efficacy of the combination formulation. Clinical trials on dentin hypersensitivity exhibit variability in study design, endpoints, and statistical approaches, which can influence the interpretation of results. [11] Previous microscopic and morphological studies, including scanning electron microscopy (SEM) observations, have demonstrated that desensitizing agents can induce partial or complete occlusion of dentinal tubules by forming surface deposits or precipitates. [24, 25] Such occlusion reduces dentin permeability and limits fluid movement within the tubules, which is considered a key mechanism underlying the reduction of dentin hypersensitivity. In particular, agents that promote mineral deposition or protein precipitation have been shown to create a protective layer over exposed dentin surfaces, contributing to both immediate and sustained effects. These structural modifications may explain the enhanced and longer-lasting efficacy observed in the combination formulation in the present study.

Differences in evaluation methods may have influenced these results. The Schiff index records a single immediate response to high-intensity air-blast stimulation, which may underestimate efficacy under maximal stimulus conditions. [13] In contrast, the Yeaple probe gradually applies pressure and measures pain thresholds, making it more sensitive to subtle changes in tactile sensitivity. Given that patients encounter various stimuli in daily life—such as cold, sweet, acidic, and mechanical triggers—multiple complementary evaluation methods are necessary to ensure a clinically meaningful assessment. [11] This approach is also consistent with the Chinese standard: WS/T 326.4-2010, which recommends using at least two types of stimuli for evaluation.

This study evaluated the immediate and sustained effects of toothpastes containing potassium nitrate alone or in combination with aluminum lactate, using multiple stimuli and assessment methods in accordance with the Chinese standard: WS/T 326.4-2010. The findings align with existing literature and provide a more comprehensive understanding of the temporal dynamics and clinical relevance of dual-action formulations.

The superior efficacy of the 5% potassium nitrate combined with 2.18% aluminum lactate combination is clinically significant. Aluminum lactate is a practical ingredient for daily-use toothpaste due to its cost-effectiveness, chemical stability, and ease of formulation, making it a promising option for future product development.

Additionally, the study was conducted among urban adults in China, where root surface exposure is commonly associated with factors such as aging, periodontal disease, and brushing pressure, as noted in national oral health policies. Although the evaluation was not limited to anterior teeth, demonstrating efficacy across different tooth types provides practical insights into the formulation’s applicability in this population.

The immediate effect on tactile sensitivity suggests that the combination of potassium nitrate and aluminum lactate may help reduce pain during tooth brushing, thereby supporting continued self-care. The sustained effect on air-blast sensitivity may alleviate pain during eating and drinking, enhancing the practical value of the toothpaste formulation in everyday life. Overall, this combination appears to offer both rapid onset and prolonged efficacy, suggesting it may be a promising dual-action option for managing DH. From a formulation perspective, future research should prioritize enhancing ingredient bioactivity—through optimization of particle size, pH, and base interactions—and investigating the complementary effects of combined ingredients.

This study had several limitations. First, although immediate effects were evaluated, pain during actual tooth brushing was not directly measured, limiting ecological validity. Second, age-related differences in sensitivity and treatment response were not analyzed despite the possibility that older individuals may experience DH due to enamel cracks or gingival recession. Third, the follow-up period was limited to 8 weeks, so long-term durability was not verified. Natural tubule occlusion may occur over weeks to months and varies among individuals, with the risk of re-exposure to acidic intake or mechanical stimuli. Finally, the study population was restricted to urban adults in China, and regional factors may affect the generalizability of the findings.

This study should be interpreted as a feasibility-oriented randomized clinical investigation conducted under national guideline conditions (WS/T 326.4-2010). While alternative statistical approaches, such as analysis of covariance (ANCOVA) and full CONSORT reporting, may strengthen future studies, the present design reflects regulatory and practical conditions for evaluating desensitizing toothpastes in China.

Conclusions

Both toothpaste—5% potassium nitrate alone and 5% potassium nitrate combined with 2.18% aluminum lactate—effectively reduced dentin hypersensitivity, with the combination formulation demonstrating superior efficacy at multiple time points. These findings support the clinical utility of dual-action desensitizing toothpaste and provide evidence to guide practitioners in selecting the most effective formulations. Future studies should include age-stratified analyses and long-term trials under real-world conditions. Additionally, tailoring formulations and evaluation protocols to address stimuli more commonly experienced by younger individuals (e.g., acidic beverages, orthodontic appliances) may further improve clinical outcomes.

Author contributions

Conceptualization: GI, NS, YF, ZZ; Methodology: DH, ZZ; Formal analysis: KI, CA, DH, ZZ; Investigation: ZZ; Resources: TS, NK, RZ, DL, Data Curation: ZZ; Writing – original draft: KI, CA; Writing – Review & Editing: KI, CA, NS, YF, KS, DL, DH; Visualization: KI, CA; Supervision: NK, DL; Project administration: ZZ, DH.

Funding

This study received no specific grants from public, commercial, or nonprofit funding agencies.

Data availability

No datasets were generated or analyzed in the current study.

Competing interests

KI, TS, CA, GI, NS, YF, KS and NK are employees of Lion corporation. RZ and DL work for Lion Innovation Center (Shanghai) Co., Ltd. DH and ZZ received research grants from Lion Corporation.