Effect of photobiomodulation with low-level laser therapy combined with potassium nitrate on controlling post-bleaching tooth sensitivity: clinical, randomized, controlled, double-blind, and split-mouth study

Role of induced nitric oxide synthases in orofacial nociception/discomfort after dental tooth bleaching with hydrogen peroxide

OBJECTIVE

To evaluate the role of induced nitric oxide synthase (iNOS) in nociception/orofacial discomfort in rats submitted to tooth whitening with hydrogen peroxide (H₂O₂).

DESIGN

Wistar rats were divided into three groups (n = 24/group): a sham group not submitted to whitening treatment, a saline group submitted to whitening treatment, and a test group submitted to whitening treatment and blockade of iNOS with aminoguanidine 50 mg/kg/day. After 24 and 48 h, and 7 days, the animals were euthanized to collect trigeminal ganglia and maxillae to histomorphometric analysis (size of neuronal bodies and percentage of pulp area filled by vessels) and behavior/nociception (Grimace scales, scratching and biting counting, weight loss and nociception assay). ANOVA-1- or - 2-way tests were used (p < 0.05, GraphPadPrism 5.0).

RESULTS

The aminoguanidine-treated group showed a reduction in nociceptive threshold in the masseteric region (p < 0.001), Grimace scale scores (p < 0.001), number of scratching (p = 0.011) and body mass loss (p = 0.007). After 24 and 48 h of tooth bleaching, the saline group showed a significant increase in the mean area of the blood vessels (p = 0.020) and iNOS immunostaining in odontoblasts (p = 0.002) and non-odontoblasts cells (p = 0.025). Aminoguanidine reversed both increases. Tooth bleaching reduced the mean area of neuronal bodies, and aminoguanidine significantly reversed it (p = 0.019), but an increase in GFAP immunostaining in neuronal bodies did not reduce after seven-days or after aminoguanidine treatment (p = 0.003).

CONCLUSION

iNOS blockage by aminoguanidine plays an important role in nociception and orofacial discomfort by control of inflammation in dental pulp after tooth bleaching with hydrogen peroxide (H₂O₂) 35%.

The effect of photobiomodulation therapy associated with casein phosphopeptide-amorphous calcium phosphate fluoride paste on the treatment of posthome whitening tooth sensitivity and color change: A randomized clinical trial

OBJECTIVE

This study assessed whether combining photobiomodulation therapy (PBMT) with casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) paste can effectively reduce post-home whitening tooth sensitivity (TS) without compromising shade change.

METHODS

Fifty participants were selected and assigned to one of four groups: (1) PLACEBO group-received a placebo paste and PBMT simulation; (2) PBMT group-received a placebo paste + PBMT; (3) CPP-ACPF group-received CPP-ACPF paste and PBMT simulation; (4) CPP-ACPF + PBMT group-received both CPP-ACPF paste and PBMT. The participants used whitening trays containing 22% carbamide peroxide for 2 h a day for 21 days. TS was measured daily using a visual analog scale, while shade change was assessed using a spectrophotometer: before bleaching treatment (T0), after the first (T1), second (T2), and third (T3) weeks of treatment, and 30 days (T4) after completing the whitening treatment.

RESULTS

Intragroup analysis revealed that the PLACEBO group had the highest increase in sensitivity during the whitening treatment. The CPP-ACPF and PBMT groups showed no significant difference tooth whitening (TW) between weeks regarding aesthetic change. The CPP-ACPF and PBMT group exhibited a significant reduction in TS between the first and third and between the second and third weeks TW, but not between the first and second. Conversely, the PLACEBO group showed a higher sensitivity than the other groups (p < .05). The CPP-ACPF and PBMT groups did not differ from each other. Furthermore, the CPP-ACPF and PBMT group showed a greater decrease in sensitivity than the PLACEBO group at T1, T2, and T3 (p < .01), and was significantly differed from CPP-ACPF and PBMT groups only at T2 and T3. All groups confirmed TW effectiveness. Student's and paired t-test did not reveal any significant difference between groups (p > .05).

CONCLUSION

Therefore, PBMT associated with CPP-ACPF paste can reduce TS without compromising the efficacy of TW.

Use of infrared photobiomodulation with low-level laser therapy for reduction of bleaching-induced tooth sensitivity after in-office bleaching: a double-blind, randomized controlled trial

The purpose of this study is to evaluate the use of infrared photobiomodulation with low-level laser therapy (PBM) to reduce bleaching-induced tooth sensitivity (TS) after in-office bleaching. Eighty-three participants were randomized in blocks into two groups. In the experimental group, the patients received an application after each session of in-office bleaching (35% hydrogen peroxide, 1 × 50 min; 2 sessions with 1-week interval), while the laser application was simulated in the control group. The PBM system was operated in continuous mode, using 3 J of energy. A dose of 100 J/cm2 was applied for 30 s with 808 nm (100 mW of power) in the middle third of the crown. The risk and intensity of TS were recorded immediately after bleaching, 1 h, 24 h, and 48 h after each bleaching session, with a visual scale analog (0-10) and a five-point numerical scale (0-4). The color was recorded at the beginning, weekly, and 1 month after the end of the bleaching (VITA Classical, VITA Bleachedguide, and digital spectrophotometer). The risk of TS was 98% (95% CI 88 to 99%) for the laser group and 95% (95% CI 83 to 99%) for the control (RR = 1.03; 95% CI 0.94 to 1.12; p = 1.0). Similarly, no difference in the intensity of TS was detected for both pain scales (p > 0.65). Improvement in color change, regardless of the group, was observed (p > 0.15). The application of an PBM did not reduce the risk and intensity of TS when applied after the procedure using the parameters recommended by the manufacturer.Trial registration number and date of registration: RBR-4HCVSG-04/06/2019.

The effect of photobiomodulation using low-level laser therapy on tooth sensitivity after dental bleaching: a systematic review

The authors aimed to conduct a systematic review to assess data from the current literature on the effectiveness of low-level laser therapy (LLLT) in preventing tooth sensitivity (TS) after tooth whitening (DB). PRISMA guidelines for systematic reviews were followed. Clinical trials evaluating the treatment of LLLT in patients with sensitivity after tooth whitening were selected. A full bibliographic search was performed on May 4, 2021, in the following databases: Embase, MEDLINE via PubMed, SciELO, VHL Regional Portal, Web of Science, Gray Literature, Scopus, ClinicalTrials.gov and Cochrane Library. This study followed Cochrane's recommendations for analyzing risk of bias. A total of 1054 studies were found (255 studies were excluded because they were duplicates and 785 because of titles and abstracts). Only 14 articles were selected for analysis, of which eight were excluded because they had one or more exclusion criteria, resulting in six articles included in this systematic review, the vast majority being classified as low risk of bias. The studies reviewed indicated that LLLT showed promise in preventing TS after TB. However, evidence is limited and more clinical trials with low risk of bias are needed to reach a definitive conclusion on the action of LLLT in pain control after TB.

Post-Operative Sensitivity and Color Change Due to In-Office Bleaching With the Prior Use of Different Desensitizing Agents: A Systematic Review

Bleaching agents can cause certain surface alterations on the enamel, such as depressions, surface porosity, and surface irregularities; this makes the dentin more susceptible to post-operative tooth sensitivity (PoS). In addition, the presence of flawed or leaky restorations, gingival recession, or defects in the cementoenamel junction can also cause severe tooth sensitivity post tooth bleaching.Hence, the current study aimed to perform a systematic review to determine the efficacy of various desensitizing agents (DA) in managing post-operative tooth sensitivity and color alteration when applied before in-office bleaching procedures. Randomized clinical trials were searched to conduct an SR where the post-operative tooth sensitivity was evaluated after in-office bleaching with various desensitizing agents used before the procedure. Post-operative pain assessment was measured using the Visual Analogue Scale (VAS). Outcomes were evaluated up to an hour and 24 hours post the procedure. Out of 163 articles, only 13 titles were selected that met the eligibility criteria. Eight hundred and forty-one adult patients with vital pulp status were included. The participants receiving prior desensitizing agent applications reported significantly lower pain scores in the VAS reports. The most significant reduction of post-operative sensitivity was observed in the immediate (up to an hour) and 24 hours after the in-office bleaching. The popular desensitizing agent that could manage post-operative tooth sensitivity (TS) is 5% potassium nitrate and 2% sodium fluoride used before the in-office bleaching procedure. 

LED photobiomodulation effect on the bleaching-induced sensitivity with hydrogen peroxide 35%-a controlled randomized clinical trial

OBJECTIVES

The aim of this study was to evaluate the effect of a protocol of photobiomodulation (PBM) with light-emitting diodes (LED) on the clinical risk of bleaching-induced sensitivity.

MATERIALS AND METHODS

Sixty-four volunteers were selected and randomly divided in two groups, placebo (PG) and LED (LG). The LG received PBM irradiation and tooth bleaching, while the PG received tooth bleaching and simulation of the irradiation. The occurrence of painful sensitivity was recorded during the dental bleaching; immediately after bleaching; and 24, 48, and 72 h after tooth bleaching. At the same measurement times, data were collected on the intensity of sensitivity (VAS and NRS scale) and teeth affected by bleaching-induced sensitivity. A questionnaire sought to measure how the painful sensitivity influenced basic daily activities. Tooth color measures were performed using subjective and objective methods.

RESULTS

LED irradiation decreased the occurrence of sensitivity at all studied evaluation times as well as its intensity, with the exception of the 72-h data when both groups presented no difference. Teeth affected by bleaching-induced sensitivity were significantly greater in the PG. Color measurements presented no differences between the groups in the recently after and later measures.

CONCLUSIONS

PBM with LED decreases sensitivity risk and sensibility intensity during and after office bleaching and causes no influence on the shade degree of whitening achieved. The decrease in tooth sensitivity provided more comfort and less suffering while drinking.

CLINICAL RELEVANCE

LED irradiation is a promising intervention in the control of bleaching-induced sensitivity.

TRIAL REGISTRATION

RBR-7hpfwj. Sensitivity intensity measured by the VAS scale (0-10) in the first whitening session (Graphic A) and second whitening session (Graphic B). Significance level set at ≤ 5%. *Mann-Whiteney U test. Columns followed by the same letter are significant different (ap < 0.001; bp < 0.001; cp < 0.001; dp =0.013; ep < 0.001; fp < 0.001; gp < 0.001; hp = 0.002).

Effectiveness of sodium fluoride varnish and/or diode laser in decreasing post-bleaching hypersensitivity: A comparative study

Background

Professional tooth whitening has gained popularity in the past several years. The most commonly active chemical agent used in bleaching is hydrogen peroxide (HP). HP is a low molecular weight unstable material that easily diffuses into the tooth structure, causing oxidative reactions with a consequent whitening effect. After bleaching, tooth sensitivity and gingival irritation are anticipated.

Aim

This study aimed to compare the effectiveness of remineralization and/or diode laser therapies in reducing tooth sensitivity after bleaching.

Methodology

Thirty-nine participants from Umm Al-Qura University, dental clinics, Makkah, SA. They were divided into three equal groups according to the desensitizing technique used. All participants were subjected to bleaching by 40% opalescence boost HP. Subsequently, 13 participants received 5% sodium fluoride varnish (5% NaF), 13 participants received low-level laser therapy (LLLT), and 13 participants received a combination of both desensitizing techniques. Each participant represented self-control, where tooth sensitivity was measured before and after bleaching. The cold test was used to measure tooth sensitivity before bleaching, immediately after bleaching and after application of the proposed desensitizing technique. Then, a visual analogue scale (VAS) was used for re-assessment.

Results

The desensitizing methods exhibited a notable reduction in tooth sensitivity post-bleaching with no significant difference among the following therapies (p = 0.544).

Conclusion

All the employed desensitizing methods reduced post-bleaching sensitivity, with no significant differences among them. Thus, using one technique individually is enough for effort, time and cost savings.

Topical application of a desensitizing agent containing potassium nitrate before dental bleaching: a systematic review and meta-analysis

OBJECTIVES

To conduct a systematic review and meta-analysis to evaluate the risk and intensity of tooth sensitivity (TS) after topical application of desensitizers containing potassium nitrate before dental bleaching.

METHODS

We searched PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library, and SIGLE. We also surveyed gray literature without restrictions. We meta-analyzed the data using the random-effects model to compare potassium nitrate and placebo in terms of risk and intensity of TS and color change (∆SGU or ∆E). The quality of the evidence was rated using the GRADE approach. The risk of bias (RoB) of the included studies was analyzed using the Cochrane RoB tool.

RESULTS

After the database screening, 24 articles remained. A significant 12% lower risk for the groups where desensitizing agents were applied (p = 0.02), with a risk ratio of 0.88 (95% CI 0.78 to 0.98). About the intensity of TS, a significant average mean difference of - 0.77 units of VAS units (95%CI - 1.34 to - 0.19; p = 0.01) in favor of the desensitizer group. In the NRS scale, a significant average mean difference of - 0.36 (95% CI - 0.61 to - 0.12; p value = 0.004) in favor of the desensitizer group. No significant difference was observed in color change (p > 0.28) in ∆SGU and ∆E.

CONCLUSIONS

Although a significant reduction in the risk and intensity of TS was observed in groups treated with a potassium nitrate at some point during the bleaching, the clinical significance of this reduction is subtle and clinically questionable. Color change is not affected by the use of agents.

CLINICAL RELEVANCE

The reduction in the risk and intensity of TS with the topical application of potassium nitrate-based desensitizing agents in dental bleaching is subtle and maybe clinically questionable.

Combination of strontium chloride and photobiomodulation in the control of tooth sensitivity post-bleaching: A split-mouth randomized clinical trial

Objective

This split-mouth randomized controlled clinical trial assessed the effect of 10% strontium chloride in combination with photobiomodulation (PBM) for the control of tooth sensitivity (TS) post-bleaching.

Methods

The upper/lower, right and left quadrants of fifty volunteers were randomized and allocated to four groups (n = 25): PLACEBO—placebo gel + simulation of PBM; Placebo + PBM; STRONTIUM—10% strontium chloride + simulation of PBM; and PBM + STRONTIUM—10% strontium chloride + PBM. All groups received tooth bleaching treatment with 35% hydrogen peroxide. For the PBM treatment, the laser tip was positioned in the apical and cervical regions of the teeth bleached in the respective hemi-arch. The laser system was operated in continuous mode, using 1.7 J of energy. A dose of 60 J/cm² was applied to each point for 16 seconds under 808 nm near-infrared light (100mW of power), with a point area of 0.028 cm². TS was assessed during a 21-day follow-up, using the modified visual analogue scale.

Results

In the intragroup assessment, the Friedman test indicated that PBM + STRONTIUM promoted the greatest reduction in TS after the second week of treatment (p ≤ 0.05). The Wilcoxon-Mann-Whitney test indicated that the groups Placebo + PBM, STRONTIUM, and STRONTIUM + PBM did not differ statistically (p ≥ 0.05) in the first and third weeks of treatment The group PLACEBO exhibited the greatest TS in the first three days after each bleaching session.

Conclusion

The combination of 10% strontium chloride with PBM was effective in reducing post-bleaching TS; however, the combination of 10% strontium chloride with PBM was effective in reducing post-bleaching TS; however, it did not differ from the individual use of Placebo + PBM or STRONTIUM groups assessed after 21 days of follow-up.

The combined use of systemic analgesic/anti-inflammatory drugs and a bioactive topical desensitizer for reduced in-office bleaching sensitivity without jeopardizing the hydrogen peroxide efficacy: a randomized, triple blinded, split-mouth clinical trial

OBJECTIVE

To evaluate the effect of combined systemic administration of paracetamol 500 mg/codeine phosphate 30 mg (PACO) and postoperative topical application of a bioactive desensitizer on in-office bleaching sensitivity and tooth color change.

MATERIALS AND METHODS

A randomized, triple-blind, split-mouth clinical trial was conducted. Forty volunteers ingested PACO (n = 20) or placebo (PLA) (n = 20). Their left/right hemiarches received topical application of a bioactive desensitizer [Nano-P™(NP)] and prophylactic paste (PAS), generating four treatment approaches: PACO/NP, PACO/PAS, PLA/NP, and PLA/PAS. Two bleaching sessions (35% hydrogen peroxide) were performed, and the PAS/NP were applied after the procedure. Sensitivity was obtained since the first bleaching session up to 7 days post-bleaching. The color change was evaluated using CIEDE2000 and whiteness index parameters up to 7 days post-bleaching. Data were analyzed using one- and two-way ANOVA/Tukey post hoc tests (p < 0.05).

RESULTS

The PLA/PAS showed a sensitivity average of at least two times higher than the PACO/NP. The treatment approaches promoted statistically similar bleaching patterns (p > 0.05).

CONCLUSION

The combined approach of systemic administration of PACO and postoperative topical application of NP reduced the level of in-office bleaching sensitivity without jeopardizing hydrogen peroxide efficacy.

CLINICAL RELEVANCE

Professionals can adopt the combined approach of systemic administration of analgesic/anti-inflammatory drugs and topical application of a bioactive desensitizer for decreased bleaching sensitivity caused by 35% hydrogen peroxide in-office.

A Spectrophotometric Study on Light Attenuation Properties of Dental Bleaching Gels: Potential Relevance to Irradiation Parameters

Background: During in-office bleaching, appropriate light sources are applied in order to enhance the activity of the bleaching gels applied onto teeth. For this method to be effective, a high absorption of light within the gel is necessary. Variation in the light attenuation capability of the gel, the duration of application and light activation can contribute towards safety hazards associated with this procedure. Methods: In this study, seven different gels and hydrogen peroxide have been evaluated for their optical properties by means of spectrophotometry (440–1000 nm). The transmitted light spectrum was used to estimate the intensity loss for each gel. The mean intensity decreases observed were statistically analysed using an analysis of variance (ANOVA). Results: The five more-pigmented gels tested indicated a very similar intensity loss of around 80%, whereas the remaining two gels showed significantly less attenuation (predominantly, p < 10⁻⁶). Conclusions: Throughout the spectrum of wavelengths examined, and according to the underlying studies evaluated, five of the gels assessed demonstrated an attenuation high enough to possibly avoid overheating of the underlying enamel dentine and pulp. An evaluation of appropriate irradiation parameters is proposed.

Effect of Prior Application of Desensitizing Agent on the Teeth Submitted to In-Office Bleaching

This study aimed to quantify the penetration of hydrogen peroxide, color change evaluation, surface morphology, and composition after application of desensitizing agents before in-office bleaching. Fifty premolars were sectioned, an acetate buffer was placed in the pulp chamber and divided into five groups (n=10). In the positive control group, only the in-office bleaching gel was used, and in the negative control group, no treatment was used. Three different desensitizing agents were applied: Desensibilize KF2%® group; Mi Paste® group, and Desensibilize Nano-P® group. The bleaching procedure was carried out with 35% HP. The absorbance of the resulting solution was determined in a spectrophotometer. Color change was assessed by using a digital spectrophotometer. Four additional premolars were assigned to the same groups above for analysis under scanning electron microscope, as well as to evaluate the elemental composition with X-ray dispersive energy spectrometry. Data were subjected to ANOVA and Tukey's test (α=0.05). All products reduced the penetration of HP in the pulp chamber. Mi Paste and Nano P were the products that yielded the lowest HP penetration, which was similar to the negative control group (p<0.001). No significant difference was detected in color change (p<0.001). Concerning enamel morphology, the groups that were analyzed after bleaching were observed a greater deposition of desensitizing agents on the surface. The use of desensitizing agents before tooth bleaching seems to be an alternative to reduce adverse effects of the tooth.

Alencar C, de Paula BLF, de A. Jassé FF, Araújo JLN, Silva CM. Photobiomodulation vs. Placebo on Post-Bleaching Sensitivity and Color Change: A Split-Mouth Clinical Study

Objective:

This study aimed to investigate the efficiency of Photobiomodulation (PBM) with low-level LASER therapy compared to placebo in post-bleaching sensitivity and color change during a three-week office bleaching treatment.

Methods:

A split-mouth model was used to evaluate 21 subjects. The right and left hemi-archs were randomized to one of two groups: GP (placebo): simulated LASER application followed by tooth bleaching with 35% hydrogen peroxide; and GL: treated with PBM followed by tooth bleaching with 35% hydrogen peroxide. A four-degree modified Visual Analog Scale (VAS) was used to assess tooth sensitivity after the application of an evaporative stimulus (stimulated pain). In addition, a daily questionnaire was used to measure unstimulated pain. The color change was measured using a spectrophotometer. The Friedman and Wilcoxon tests were used to analyze data sensitivity. Color results were statistically analyzed using Analysis Of Variance (ANOVA) followed by the Tukey post-hoc test.

Results:

There was no significant difference between GP and GL for stimulated pain evaluation (p> 0.05). However, there was a significant difference between the groups for unstimulated pain evaluation (p≤ 0.05). In addition, ΔE data did not reveal any significant difference in tooth color between groups at any time (p> 0.05).

Conclusion:

PBM prevented post-bleaching sensitivity compared to placebo, based on the daily pain assessment questionnaires. PBM did not compromise the quality of bleaching treatments.

Influence of low-level laser therapy on inflammation, collagen fiber maturation, and tertiary dentin deposition in the pulp of bleached teeth

OBJECTIVES

We evaluated the effects of low-level laser therapy (LLLT) using an infrared laser (IRL) and a red laser (RL) on the pulp of molar teeth in rats after dental bleaching to assess inflammation, collagen fiber maturation, and tertiary dentin formation.

MATERIALS AND METHODS

Eighty Wistar rats (Rattus norvegicus, albinus) were randomly divided into eight groups with 10 hemimaxillae in each of the following: control; bleached (Ble, 35% hydrogen peroxide [H₂O₂]); Ble-1IRL and Ble-1RL (one IRL [808 nm, 30 s, 3 J] or RL [660 nm, 15 s, 1.5 J] application immediately after H₂O₂); Ble-3IRL and Ble-3RL (three [immediately, 24 h, and 48 h] IRL or RL applications after H₂O₂); and 3IRL and 3RL (three IRL or RL applications without bleaching). The rats were euthanized after 2 and 30 days for histological evaluation of inflammation (hematoxylin-eosin) and maturation of collagen fibers (picrosirius red). Additionally, the dentin deposition in the specimens obtained at 30 days was quantified via microtomography of the pulp chamber volume. Statistical analyses were performed (P < 0.05).

RESULTS

Initially, severe damages to the pulp were observed in the Ble and Ble-1RL groups. Ble-1IRL and Ble-3RL groups showed lower inflammation. The bleached groups had a greater amount of mature collagen fibers than the control group. The Ble-3IRL group had a greater number of immature fibers than the Ble group. At 30 days, there was an absence of inflammation and equal proportion of mature and immature collagen fibers. All bleached groups showed a reduction in the volume of the pulp chamber.

CONCLUSION

Three consecutive applications of RL and one IRL application can minimize damage to the pulp of bleached teeth, whereas three IRL applications can minimize pulp fibrosis. However, LLLT did not prevent deposition of tertiary dentin.

CLINICAL RELEVANCE

This study describes LLLT protocols capable of minimizing inflammation and maturation of collagen fibers in pulp tissue after dental bleaching. However, the protocols proved insufficient for reducing the formation of tertiary dentin in bleached teeth.

Photobiomodulation in Endodontic, Restorative, and Prosthetic Dentistry: A Review of the Literature

Objective: To provide a review of the literature about the photobiomodulation therapy (PBMT) dental treatment protocols in endodontic, restorative, and prosthetic dentistry based on validated clinical studies published so far. More specifically, this study was carried out to carefully review therapeutic protocol of PBMT in clinical studies and their conclusions. Background data: The importance of using low-power lasers and photobiomodulation (PBM) is increasing in dentistry mainly due to their painless and noninvasive function. However, lack of sufficient clinical studies has led to unclear results regarding PBMT in dentistry, and also lack of an available precise protocol for clinicians. Moreover, scarcity of clinical studies in this area has made conduction of a precise systematic review study difficult. Methods: In our study, published clinical studies up to April 2019 were reviewed from library sources, Google Scholar, PubMed and Medline, Elsevier, Embase, Cochrane, Scopus, and Web of science (ISI). Inclusion criteria included those presented in clinical trials and case report/case series, language (English), and studies available in full text. Exclusion criterion was in vitro studies. Results: In general, findings of clinical studies have shown that PBMT can have a significant role in reducing postoperative dental pain, increasing depth of anesthesia, improving tooth hypersensitivity, reducing inflammation of the tissue, and helping wound healing. Conclusions: A review of clinical studies showed that the use of alternative or adjunctive PBMT is of great importance in controlling postoperative pain after endodontic treatments. In addition, evidence suggests that different parameters of light can be efficient in the treatment of tooth hypersensitivity. Nevertheless, lack of sufficient clinical studies and reliable results do not allow introducing a precise treatment protocol.