ABSTRACT
Introduction:
Teeth whitening is one of the most frequently requested cosmetic dental procedures. However, concerns about the long-term impact of various whitening methods on enamel microhardness and patient satisfaction remain. This study aimed to evaluate the effects of three commonly used whitening techniques—professional in-office bleaching, at-home bleaching, and over-the-counter (OTC) products—on enamel microhardness and patient satisfaction over time.
Methods:
A total of 90 participants were divided into three groups: 30 received in-office bleaching, 30 performed at-home bleaching, and 30 used OTC whitening products. Enamel microhardness was measured before and after treatment using a Vickers microhardness tester. Patient satisfaction was assessed via a standardized questionnaire at two intervals: immediately post-treatment and three months later.
Results:
Significant differences were found between the groups regarding enamel microhardness, with in-office bleaching causing the greatest reduction (P < 0.05). At-home bleaching showed a moderate decrease, while OTC products had the least impact on microhardness. In contrast, patient satisfaction was highest in the in-office bleaching group, followed by at-home and OTC groups.
Conclusion:
Although in-office bleaching led to a significant reduction in enamel microhardness, it was associated with the highest patient satisfaction. This highlights the need for clinicians to balance efficacy and enamel preservation when recommending whitening treatments.
KEYWORDS: Enamel microhardness, in-office bleaching, over-the-counter whitening, patient satisfaction, teeth whitening
INTRODUCTION
Tooth discoloration is a major aesthetic concern for many individuals, driving the demand for various teeth-whitening products and procedures. The advent of over-the-counter (OTC) products, at-home bleaching kits, and professional in-office whitening has provided patients with multiple options to achieve their desired results. However, there is ongoing debate regarding the long-term effects of these techniques on enamel microhardness and overall patient satisfaction.[1,2]
Enamel microhardness is a crucial factor in dental health, as it influences the tooth’s resistance to wear, decay, and damage. Studies have shown that the use of bleaching agents, particularly those with high hydrogen peroxide concentrations, can reduce enamel microhardness.[3] However, patient satisfaction is often determined by the speed and efficacy of the whitening process, with professional treatments yielding more immediate and noticeable results.[4] This study aims to compare the effects of in-office bleaching, at-home bleaching, and OTC whitening on enamel microhardness and patient satisfaction, with a focus on long-term outcomes.
METHODS
Study design
This prospective, randomized clinical study involved 90 participants aged 18-45, with no prior history of tooth whitening or enamel disorders. The participants were randomly divided into three equal groups:
In-office bleaching (n = 30): Participants received professional treatment using 35% hydrogen peroxide activated by a light source.[5]
At-home bleaching (n = 30): Participants used a 10% carbamide peroxide gel in custom trays for 14 consecutive days.[6]
OTC whitening (n = 30): Participants used an OTC whitening kit containing 6% hydrogen peroxide strips.[7]
Enamel microhardness measurement
Baseline enamel microhardness was measured using a Vickers microhardness tester. The same measurements were repeated 24 h after completing the whitening regimen and again three months later. The mean value of three indentations on each tooth was recorded.
Patient satisfaction assessment
Patient satisfaction was assessed using a standardized questionnaire that evaluated immediate post-treatment satisfaction and long-term satisfaction after three months. The questionnaire included questions about perceived whitening efficacy, sensitivity, and willingness to recommend the treatment to others.
Statistical analysis
Data were analyzed using analysis of variance (ANOVA) for comparisons of enamel microhardness between the three groups, and post hoc Tukey’s tests were applied where significant differences were found. A paired t-test was used to compare baseline and post-treatment microhardness values within each group. A P value of < 0.05 was considered statistically significant.
RESULTS
Enamel microhardness
The baseline enamel microhardness was comparable across all groups (P > 0.05). However, significant reductions in enamel microhardness were observed after treatment in all groups. The in-office bleaching group showed the greatest reduction, with an average decrease of 18% from baseline (P < 0.01). The at-home bleaching group exhibited a 12% reduction, while the OTC group had the smallest change at 6% [Table 1].
Table 1.
Changes in enamel microhardness across groups
| Group | Baseline microhardness (HV) | Post-treatment (HV) | Three months (HV) |
|---|---|---|---|
| In-office bleaching | 360 | 295 | 300 |
| At-home bleaching | 355 | 310 | 315 |
| OTC whitening | 350 | 330 | 340 |
HV=hardness Vickers, OTC=over-the-counter
Patient satisfaction
Patient satisfaction scores varied significantly between groups (P < 0.05). The in-office bleaching group had the highest satisfaction score immediately post-treatment (mean score: 4.8/5), while the OTC group had the lowest score (mean score: 3.5/5). Interestingly, at the three-month follow-up, satisfaction scores declined in all groups, but the in-office bleaching group maintained the highest satisfaction [Table 2].
Table 2.
Patient satisfaction scores across groups
| Group | Immediate satisfaction score | Three-month satisfaction score |
|---|---|---|
| In-office bleaching | 4.8/5 | 4.6/5 |
| At-home bleaching | 4.2/5 | 3.9/5 |
| OTC whitening | 3.5/5 | 3.3/5 |
OTC=over-the-counter
DISCUSSION
The present study provides a comparative analysis of the long-term effects of three widely used teeth whitening techniques on enamel microhardness and patient satisfaction. Consistent with previous research, in-office bleaching led to a significant reduction in enamel microhardness.[1,5] This can be attributed to the high concentration of hydrogen peroxide (35%) and the use of light or laser activation, which can accelerate the oxidative reaction but also increase enamel demineralization.[4] However, the at-home bleaching group showed a moderate reduction in enamel hardness, likely due to the lower concentration of carbamide peroxide (10%) and the extended application time, which allows for less aggressive whitening.[3]
OTC products, while convenient and widely available, caused the least reduction in enamel hardness. This is likely due to the significantly lower concentration of whitening agents (6% hydrogen peroxide), making them less effective but also less damaging to the enamel.[6] These findings are consistent with earlier studies that highlighted the balance between whitening efficacy and enamel safety.[2,7]
Despite the variations in enamel microhardness, patient satisfaction remained highest with in-office treatments. This could be attributed to the immediate and noticeable results that patients seek when opting for professional whitening.[5] At-home and OTC products, while causing less reduction in enamel hardness, were associated with lower satisfaction scores, possibly due to the slower and less dramatic whitening effects.[8] Over time, satisfaction scores in all groups decreased, but in-office bleaching still led to the highest overall satisfaction even after three months.[9]
These findings underscore the importance of educating patients about the potential trade-offs between efficacy and enamel preservation when choosing a whitening technique. Clinicians should consider individual patient needs, such as the desire for rapid results versus the need to preserve enamel health, when recommending a treatment.[10,11]
CONCLUSION
In-office bleaching, while providing the most dramatic whitening results and the highest patient satisfaction, also caused the greatest reduction in enamel microhardness. At-home bleaching offered a moderate balance between efficacy and enamel preservation, while OTC products were the least damaging to enamel but also the least effective. Clinicians must weigh these factors when advising patients on long-term whitening options.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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