The influence of desensitizing dentifrices on pain induced by in-office bleaching

The purpose of this study was to evaluate whether the use of desensitizing dentifrices used 15 days prior to and after in-office tooth bleaching could eliminate or reduce tooth sensitivity. After institutional review board approval and informed consent, 45 subjects were selected and divided into 3 groups according to the dentifrice selected: Colgate Total (CT), Colgate Sensitive Pro-Relief (CS) or Sensodyne ProNamel (SP). The subjects used toothpaste and a toothbrush provided to them for 15 days prior to bleaching. They were then submitted to two in-office bleaching sessions (Whiteness HP Blue Calcium). Their tooth sensitivity was assessed using the Visual Analog Scale (VAS) for a week after each session. Their tooth shade alteration was measured with a Vitapan Classical shade guide to determine if the dentifrices could influence the effectiveness of the bleaching agent. The data were submitted to Wilcoxon, Kruskal-Wallis and Mann-Whitney tests (α = 0.05). The use of desensitizing dentifrices did not affect the bleaching efficacy. In regard to tooth sensitivity, there was a statistically significant difference between the results of the Control Group and Group T2 after the first session (p = 0.048). There was no statistically significant difference in the results for the other groups after the first session. In regard to the second session, there was no statistically significant difference in the results for all the groups. The use of a desensitizing dentifrice containing nitrate potassium reduced tooth sensitivity during the bleaching regimen. Dentifrices containing arginine and calcium carbonate did not reduce tooth sensitivity. Color change was not influenced by the dentifrices used. Descriptors: Tooth Bleaching; Dentin Sensitivity; Toothpastes. Introduction Tooth color is defined as a combination of intrinsic and extrinsic staining. The main intrinsic causes of discoloration are aging and pulp necrosis, whereas the most common extrinsic causes are coffee, tea, red wine, and tobacco.1-3 Vital teeth whitening is a solution for discolored teeth, because of its conservative approach and high success rate.1,4-6 It has been theorized that the tooth bleaching mechanism is based on hydrogen peroxide (H2O2) penetration through the tooth structure due to its low molecular weight. Free radicals, such as perhydroxyl (HO2), are able to oxidize chromophores and break them down into less complex molecules that reflect more light.5,7-9 Declaration of Interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript. Submitted: Feb 19, 2013 Accepted for publication: Jul 31, 2013 Last revision: Aug 20, 2013 http://dx.doi.org/10.1590/S1806-83242013000600012 The influence of desensitizing dentifrices on pain induced by in-office bleaching 518 Braz Oral Res., (São Paulo) 2013 Nov-Dec;27(6):517-23 Whitening products of high hydrogen-peroxide concentration usually offer the best results in a short period of time, associated with mild and transient collateral effects,1-4,8,10-12 such as tooth sensitivity and gingival irritation.8,13 Brännström’s hydrodynamic theory is the most accepted explanation for tooth sensitivity and posits that it is caused by fluid movement inside the dentinal tubules.1 Recently, it has been hypothesized that sensitivity after bleaching differs from tooth sensitivity to cold and tactile stimuli, which are usually associated with root dentin exposure.14 Sensitivity after whitening probably occurs as a consequence of the functional properties of a chemosensitive ion channel called TRPA1 (transient receptor potential cation channel with ankyrin domain-type 1). This ion channel is associated with the pain caused by oxidants, including hydrogen peroxide. Since the afferent fibers of primary dental pulp contain TRPA1, it is possible that direct TRPA1 activation of nerve fibers is involved in the pain caused by tooth bleaching.14 The mechanisms responsible for tooth sensitivity after bleaching have not been fully elucidated; however, some inflammatory mediators may play an important role.1,15 These effects have commonly been reported in association with bleaching techniques and different peroxide concentrations, although inoffice whitening products cause greater sensitivity than at-home bleaching gels.8 Several approaches to reducing sensitivity after dental bleaching have been suggested. The use of fluoride2,4,16 and treatment with nonsteroidal antiinflammatory drugs (NSAIDs) lead to a significant reduction in post-operative sensitivity.1 Anti-sensitivity dentifrices are another option for reducing the adverse effects of bleaching agents.17 These products act by: 1. reduction in the excitability of nerve fibers present in the pulp, and 2. obliteration of dentinal tubules.18 A reduction in the excitability of nerve fibers could occur due to the diffusion of potassium salt through the enamel and dentine. These salts can reach the nerve terminations, affect nerve impulse transmission2,10,19 and result in a reduction or deletion of pain.20 The obliteration of dentinal tubules after using strontium chloride results in a reduction in dentin permeability and blocks the hydrodynamic mechanism.20 Several years ago, products containing fluoride and potassium nitrate were launched on the market as desensitizers for professional use, dentifrices, or even associated with bleaching gels.10 More recently, products containing calcium carbonate and arginine have been marketed with the intent of providing a barrier and preventing fluid movement inside the dentinal tubules, aiming at reducing tooth sensitivity. Considering that sensitivity is the main adverse effect of tooth whitening and that information on the effects of dentifrices as desensitizing agents is scarce, the aim of this study was to evaluate the efficiency of different desensitizing agents (potassium nitrate and arginine / calcium carbonate), contained in two dentifrices, in reducing tooth sensitivity in patients submitted to an in-office bleaching protocol. In addition, the influence on tooth color was evaluated. Methodology This research was approved by the Ethics Committee on Human Research of the Universidade Federal de Santa Catarina UFSC (process number 1171 FR: 390769). All patients were selected according to inclusion and exclusion criteria (Table 1).1,3,4,21-23 Day 1 Tooth sensitivity was verified using a syringe with air spray positioned 2 millimeters from the buccal surfaces of the upper anterior teeth for 2 seconds. Patients who reported tooth sensitivity were excluded from the research.8 The patients who fulfilled all the prerequisites were given details of the bleaching procedure and were included in the research. Selected patients were randomly divided into three groups (n = 15), each of which was assigned a dentifrice (Table 2). Each patient received a soft toothbrush (Top Plus, Condor S / A, São Bento do Sul, Brazil) and a Thiesen CH, Rodrigues Filho R, Prates LHM, Sartori N 519 Braz Oral Res., (São Paulo) 2013 Nov-Dec;27(6):517-23 scale is well-known and used as an instrument to measure a characteristic or an attitude, and is based on continuous values that cannot be measured objectively. During this period the patients continued to use the toothpaste assigned to their group. Day 22 Seven days after the first bleaching session, the patients returned for a second session, which involved the same procedures. The sensitivity continued to be noted by the patients. Day 29 One week after the second bleaching session, the “sensitivity diary” was returned by the patients and a new color evaluation was performed. The whitening procedure may lead to dehydration of the teeth, and consequently induce a false, lighter aspect immediately after the end of the session.26 For this reason, an interval of one week was considered necessupply of the toothpaste type assigned to the group. There were no labels or other types of identification on the toothpaste tubes, only a code for later analysis; both the patient and the operator were blinded. The toothbrush and toothpaste were used by the patients for 15 days before the first bleaching session.2 Day 15 Fifteen days after the patients began using the assigned toothpaste, each patient received a prophylaxis in a prophylactic paste without oil (Prophylactic paste Villevie, Dentalville of Brazil Ltda., Joinville, Brazil) for the removal of extrinsic stains. The tooth color of the upper right canine was evaluated by two operators, and, in the case of disagreement, a third individual was called. The Vitapan Classical guide (Vita Zahnfabrik RauterGmbH H. & Co, BädSackingen, Germany) was organized according to a scale of values numbered 1–16.3,4,24,25 The first in-office bleaching session was performed in the maxillary arch.3,24 A resin barrier (Top Dam, FGM, Joinville, Brazil) and a lingual / lip retractor (Arcflex, FGM, Joinville, Brazil) were used. The whitening gel (35% HP Whiteness HP Blue Calcium, FGM, Joinville, Brazil) was applied on the buccal surfaces of the right second premolar through to the left second premolar, and left for 40 minutes. Each patient received a “sensitivity diary” to keep daily notes on tooth sensitivity for a period of one week, using an analogue visual scale that ranged from 0 to 10 (0 = no sensitivity / 10 = maximum sensitivity). This Inclusion Exclusion • Presence of all six maxillary teeth equal or darker than shade D2 in the Vita Classical Guide in the value order • Candidates must be willing to sign a consent form • Candidates must be at least 18 and less than 30 years of age • Absence of any kind of dental pain • Candidates must be able to return • Candidates must be non-smokers • Absence of cervical lesion and root exposure • Candidates with good oral health • Absence of dental hypersensitivity to cold and/or heat • Presence of restoration in the six anterior teeth, involving the labial surface o

Success and survival rates of mandibular overdentures supported by two or four implants: a systematic review abstract: This systematic review evaluated the influence played by the number of implants on the results of rehabilitation treatment with mandibular overdentures on 2 or 4 implants.The literature search was conducted using PubMed, Embase and Cochrane databases.Specific terms were used in performing a search from January 1980 to January 2013.The search strategy was applied by two reviewers who extracted the data and compared the results.Discrepancies were resolved by discussion.Great heterogeneity was seen among the selected studies, in regard to survival rates, prosthesis failure and function rates.A medium degree of quality and methodological consistency was found in one study, and no studies showed a high degree.When considering the prosthesis success rate for 2 implants, there was a variation of 23% to 100%.However, when considering the survival rate, the result was 92% to 100%.For 4 implants, prosthesis survival rates showed less variation, i.e., 97.7% to 100%.Ball attachments were the most common type of abutment for 2 implants; however, there was a higher prevalence of bar abutments for 4 implants.Rehabilitations with 2 implants showed more complications and required more maintenance according to the connection type.Given the limitations of this review, mandibular overdentures with 4 implants showed better results with respect to survival and success rates, especially those with a bar connection.Further studies comparing these two treatment types are necessary to improve the scientific evidence in this area.

introduction
The use of implant-retained dentures has been an alternative for treating the edentulous mandible, since it allows fixation of the prosthesis to the edentulous ridge. 1 This has encouraged dental professionals to display and perform prostheses, such as overdentures retained by implants, as an option to solve the problem of edentulous patients.Treating patients by implant placement is a popular option for restoring function and esthetics, 2 and for improving oral function, masticatory efficiency and individual satisfaction. 3claration of interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript.
Braz Oral Res., (São Paulo) 2014;28(1):1-7 There is still some debate regarding the number of implants required to properly support dentures.Studies have shown good results for oral rehabilitation with implant-retained prostheses; however, overdentures with 2 and 4 implants must be compared in the long term, with respect to clinical characteristics, patient satisfaction and ease of care. 4n addition to the success rate of osseointegrated implants supporting dental prostheses, the prosthesis itself should also be taken into consideration when determining the overall success of the rehabilitation treatment. 5Thus, the goal of this systematic review was to demonstrate the variations in success or survival rates of overdentures when 2 or 4 implants are used to treat the edentulous jaw.

methodology Search strategy
The search was conducted by 2 reviewers, independently, using electronic databases (Pubmed/ Medline, Embase, Cochrane), and was limited to clinical trials reporting the success of mandibular overdentures on 2 or 4 implants.A broad search was undertaken from January 1980 to January 2013 to identify the studies by title and abstract.The terms "overdenture," "implant-retained," "implant-supported," "success," "dental prosthesis," "complete mandibular denture" and "prosthetic outcome" were combined using "and" or "or," and a total of 967 studies were identified for initial screening.
The titles and abstracts of all reports identified through the electronic searches were assessed by 2 reviewers, and both the inclusion criteria (publications in English, follow-up of at least one year, mandibular overdentures, success rates, survival rates, failure rates or prosthesis function rate of overdentures on two or four implants, and ball and/or bar attachments) and the exclusion criteria (laboratory studies, case reports, and cross-sectional data) were applied.The literature search yielded a total of 967 citations, 951 of which were excluded because they did not meet the inclusion criteria.Any disagreement between the reviewers in the search process was resolved either by reaching a consensus or by including the reference for subsequent review.Hand-searching of the selected journals, as well as searching the references of the selected studies was also performed at this point to include any paper not found in the electronic search.Finally, full-text copies of the remaining 16 studies (Tables 1 and 2) were obtained for a more detailed evaluation.The reasons for excluding another 5 studies are listed in Table 3.
The final studies that were included after passing the second phase of the review process were classi- selected for analysis [7][8][9][10][11][12][13][14][15][16][17] (Figure 1).Methodological issues such as sample size, follow-up, attachment system, quality of assessment and results for implants and prostheses were described (Tables 1 and  2).Studies with unclear methodological issues, such as reports with a different number of implants, were excluded [18][19][20][21][22] (Table 3).This systematic review included randomized controlled trials, 16 non-randomized controlled trials, [9][10][11][12] prospective studies 7,8,13,15,17 and retrospective studies. 14Randomized clinical trials (RCT) present a better evaluation of treatment results when adequate methods are used.However, since RCTs were fied according to the quality assessment of pre-established characteristics, in order to document the methodological strength of each paper. 6The variables investigated in the quality assessment are listed in Table 4.The sample size was considered adequate when the sample size calculation was presented.Measurement methods were considered valid when a measurement error test was presented.Each study was classified based on the following scores: • low (0-5 points), • medium (6-8 points) or • high (9-10 points).

Authors (year) Exclusion criteria
Adell et al. 18 (1990) A mean of 6 implants was used Johns et al. 19 (1992) Hutton et al. 10 (1995) Jemt et al. 21(1996) A maximum of 4 implants were placed but only 2 were connected to the abutments.However, one of the sleepers was activated at some point of the treatment.Thus, 3 implants were evaluated Fartash et al. 22 (1996) Individual assessment of success rate for 2 or 4 implants was not reported uncommon for the topic researched, the clinical guidance provided to dental clinicians would be limited if this review were based solely on RCTs.Thus, it was decided that other study designs of overdentures retained by 2 or 4 implants should be included.Only one study 10 showed a medium degree of quality and methodological consistency (Table 1); most showed a low degree, and none showed a high degree.The sample size, statistical analysis and confounding factors were the most significant flaws.
The main results evaluated in the studies with overdentures (OD) focused on the influence of the number of implants on OD success.Several data were evaluated, including implant success and survival rates, prosthesis failure and functional rates.4][15][16][17] One study 8 showed results for both 2 and 4 implants.In regard to the attachment system, the ball attachment was the most commonly used system for 2 implants, and bars, for 4 implants.The prosthesis survival rates for 2 implants ranged from 92% 10 to 100%. 12However, when the protocol described by Payne et al. 23 was used to define success rate based on different criteria (success, survival, unknown, loss, retreatment by relining or replacement), the rate ranged from 23% 9 to 100%. 12For other authors, 8,13,14,16,17 individual criteria were used to define the outcomes.As can be observed, these individual criteria are reflected in the results.Authors who used the criteria successfully were stricter and sought to follow predetermined evaluation criteria.In contrast, those who used survival rates, considered only the prostheses that remained in use, despite the fact that complications may have occurred.
High survival rates were observed in the studies with four implants.The results were based on personal evaluation and criteria established by the authors regarding prosthesis function 8,13,[15][16][17] or failures. 14

Discussion
The parameters for prosthetic success showed great variability among the studies as a result of different methodologies and criteria.This becomes a challenge for significant synthesis and comparison of results.The authors used the terms success and survival as two independent characteristics.Success was defined as rehabilitation that remained unchanged, not requiring any intervention during the entire observation period, and that proceeded under ideal conditions.Survival was defined as the rehabilitation remaining in situ with or without modification and clinical management over the observation period, 24 even when repairs were made.Thus special attention had to be given when comparing the results of each parameter.
The different results were a consequence of different sample sizes, follow-up periods, attachment systems and complications.An adequate evaluation should take into consideration all of these aspects to show the prosthetic success in general, and any conclusions should be addressed carefully before applying them to dental practice.
Considering that randomized, controlled clinical trials present excellent quality, further evaluation should be conducted based on this type of study, to compare appropriate sample sizes with 2 and 4 implants and different attachment systems.It is important to highlight that any unexpected complications requiring clinical intervention should be classified as treatment complications and described in the clinical trials (prospective and retrospective), seeing that a trend was observed to report only positive results.
There were wide-ranging results for overdentures retained by 2 implants based on pre-established criteria. 23The only study with a 100% success rate was a short-term follow-up, 12 and, most probably, the evaluation period was not long enough to show any complications.Although some authors suggested that failures usually occur during the first year and decrease over time, [9][10][11]25 medium-and long-term follow-ups are recommended to assess prosthesis performance, 8 in order to determine the real trend.
A minimum of 2 and up to 4 implants are required for rehabilitation with overdentures. 26Some authors concluded that 2 implants are enough and presented this option as a low-cost alternative. 4,126][17] In two other studies, 8,14 the long-term follow-up results may justify these rates.Four implants provide better stability, and avoid both movement and excessive loading, which may compromise osseointegration. 14he attachment system plays an active role in prosthesis success rates, reflected in prosthetic maintenance and complications.Ball attachments revealed complications, such as being time-consuming and incurring costs related to wearing and loosening of matrix and patrix components that had to be changed.0][11] This kind of attachment is used basically with two implants.In contrast, the bar attachment showed better results for rehabilitation with two and four implants.Some studies suggested that implants splinted with bars are a favorable alternative to minimize rotational movement and provide vertical load transfer, 14,16 and to avoid implant micromovement and prosthetic repairs. 28Bearing this in mind, it is important that these complications be recorded when analyzing prosthesis maintenance during follow-ups.
Walton 10 evaluated the success rate based on preestablished criteria 21 to assess any difference in prosthetic maintenance between ball and bar attachments.After a 3-year follow-up, the bar-clip system exhibited a statistically significant difference in its success rate.The ball attachment required 5 times more repair than the bar system, thus lowering its success rate to 23%.
Other factors are also important in analyzing the results, such as maintenance period, types of complications and failure, time and type of repair, complexity of procedures, and prosthesis design.Although it is difficult to predict the complications, these factors should be considered during treatment planning and be informed to the patient, since they will influence treatment success.
Not only is the success of implants and prosthesis at issue, but the occurrence of complications that must be considered in evaluating the treatment.Biological failures, costs and patient satisfaction regarding function and esthetics should also be included in the final results.
Few studies showed that mandibular overdentures retained by 4 implants are an adequate alternative for an edentulous mandible, based on better success rates and prostheses survival, especially with the bar attachment system.conclusion Given the limitations of this review, mandibular overdentures with 4 implants showed better results with respect to survival and success rates, especially those with a bar connection.Further studies comparing these two treatment types are necessary to improve the scientific evidence in this area.With this in mind, long-term, randomized and appropriately designed clinical studies are recommended.

table 1 -
Results of studies with two implants.

table 2 -
Results of studies with four implants.

table 3 -
Studies excluded and reason why.

table 4 -
Characteristics and scores used for quality analysis of selected papers.