Laser therapy for dentinal hypersensitivity
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess the efficacy of in‐office employed lasers versus other therapeutic approaches, placebo laser, placebo agents or no treatment for relieving pain of dentinal hypersensitivity.
Background
Dentinal hypersensitivity (also called dentine hypersensitivity, hyperdentine, hypersensitive dentine, hypersensitive tooth or tooth hypersensitivity) is characterised by short, sharp pain from exposed dentine that occurs in response to external stimuli such as cold, heat, osmotic, tactile or chemicals (Holland 1997), and cannot be explained by any other form of dental defect or pathology (Kimura 2000). It is one of the most painful and least predictably treated chronic conditions in dentistry (Kumar 2005), which may cause considerable patient discomfort (Bartold 2006). The sufferers tend to have substantially decreased oral health‐related quality of life (OHRQoL) in comparison with the general population (Bekes 2009).
Dentinal hypersensitivity is not a single entity but a common symptom of various dental diseases. Enamel loss and dentine exposure, due to physiological abrasion of enamel or gingival recession, may cause dentinal hypersensitivity. Hargreaves and colleagues pointed out that the cervical region of incisors and premolars opposite to the dominant hand tends to be the most affected areas, suggesting that toothbrush abrasion may be an etiologic factor (Hargreaves 2002). Recently, some iatrogenic factors such as periodontal procedures and tooth whitening techniques have been reported to provoke dentinal hypersensitivity (Addy 2002; Litonjua 2003; Bamise 2008).
The prevalence of dentinal hypersensitivity ranges from 8% to 74% among the adult population (Addy 2000; Markowitz 2007; Porto 2009), and even as high as 98% among people with periodontal diseases (Orchardson 2006). The peak prevalence has been variously reported as occurring between the second and fifth decades of life (Al‐Sabbagh 2009).
Description of the condition
Efficacious management of dentinal hypersensitivity depends upon proper diagnosis in terms of the severity and location of the pain, and elimination of the predisposing factors and causes (CABDH 2003; Porto 2009). To date, numerous clinical interventions have been reported to have a positive effect in reducing dentinal hypersensitivity; these include cavity varnishes, corticosteroids, calcium compounds, oxalates, resins and adhesives, gingival augmentation and laser therapy (Addy 2002; Corona 2003; Stabholz 2004; Al‐Sabbagh 2009). A Cochrane review on efficacy of potassium containing toothpastes for the management of dentinal hypersensitivity indicated that there was little reliable evidence to support efficacy of these products (Poulsen 2006). Recently, some Chinese authors reported that local use of alcoholic extract of propolis might be effective in treatment of dentinal hypersensitivity (He 2009;Feng 2010), but this evidence should be verified further by more well‐designed clinical trials.
Description of the intervention
Laser (light amplification by stimulated emission of radiation) is an intense beam of coherent monochromatic light (or other electromagnetic radiation) generated by particular devices. Lasers have a wide range of clinical applications in dentistry and were first used for treatment of dentinal hypersensitivity in 1985 (Matsumoto 1985). To date, several types of lasers have been employed, which could be classified into two categories: low output power lasers (helium‐neon and gallium/aluminium/arsenide [diode]) and middle output power lasers (Nd:YAG and carbon dioxide [CO2]) (Kimura 2000). Clinical application of lasers in combination with chemical agents (e.g. fluoride) has also been reported as an effective therapeutic approach for controlling dentinal hypersensitivity (Kumar 2005; Ritter 2006).
Several studies have shown that lasers may be more effective compared to other treatments in reducing dentinal hypersensitivity (Kimura 2000; Porto 2009; Sicilia 2009; Yilmaz 2011); however, some researchers argue that they have no significant superiority over placebo (Lier 2002). Moreover, laser therapy has been reported to be less effective in treating severe cases (Al‐Sabbagh 2009). Some adverse effects, such as thermal effects on dental pulp, should not be neglected when lasers are used as a cure for dentinal hypersensitivity (Kimura 2000;Stabholz 2004).
How the intervention might work
Several theories have been proposed to explain the mechanism of dentinal hypersensitivity. The most accepted one is the hydrodynamic theory, assuming that the outward fluid movement within the dentinal tubules followed by external stimuli results in neural discharge and subsequently causes a painful sensation (Addy 1990). Scanning electron microscope (SEM) photographs suggest that lasers have the ability to vaporise, fuse, melt, or seal dentinal tubules probably by means of recrystallization of the mineral component of dentine.
The other theory indicates that Nd:YAG laser could block the depolarisation of A delta and C fibres and suppresses generation and/or transmission of the impulse and thus contributes to the direct nerve analgesia (Stabholz 2004). In addition, the combination of Nd:YAG laser and sodium fluoride varnish is reported to have better efficacy in reducing the number of dentinal tubules (Lan 1999; Kumar 2005).
Why it is important to do this review
Laser therapy has been widely used for dentinal hypersensitivity, and a considerable number of randomised controlled trials (RCTs) have been conducted to explore the effect of different types of lasers in comparison with placebo laser or other treatment methods (Lier 2002; Birang 2007; Ipci 2009; Kara 2009; Sicilia 2009). Recently, a meta‐analysis (He 2010) and a systematic review (Sgolastra 2011) have been conducted, but the former was limited to Chinese literature and the latter was confined to those RCTs only comparing lasers with placebo lasers. Therefore a Cochrane systematic review is important to summarise the evidence regarding the effectiveness of lasers in treating dentinal hypersensitivity, and to explore influencing factors such as type and/or intensity of the lasers, severity of the condition, tooth type and other associated parameters.
Objectives
To assess the efficacy of in‐office employed lasers versus other therapeutic approaches, placebo laser, placebo agents or no treatment for relieving pain of dentinal hypersensitivity.
Methods
Criteria for considering studies for this review
Types of studies
Randomised controlled trials (RCTs) in which in‐office laser therapies were compared to other therapeutic approaches, placebo or no treatment will be included.
RCTs with split‐mouth design, in which the interventions were randomly assigned to either side of the mouth and the outcomes were blindly assessed, will be included. Randomised cross‐over studies with adequate wash‐out period will also be included.
Types of participants
Patients aged above 18 years presenting with self‐reported tooth hypersensitivity confirmed in clinical evaluation will be considered.
Types of interventions
The test intervention will be any types of in‐office lasers having been employed in relieving pain of dentinal hypersensitivity, such as Nd:YAG, CO2, He‐Ne or GaAlAs (diode) lasers, with different radiation parameters. The control intervention will be other parallel treatment alternatives, such as placebo lasers, placebo agents, dentine sealing agents, fluoride varnishes, etc, or no treatment. The at‐home therapeutic approaches will not be considered in this review.
Types of outcome measures
Primary outcomes
1. Change in intensity of pain using quantitative pain scale (e.g. visual analogue scale) when tested through tactile, thermal or air blast stimuli.
2. Longevity of the effect (e.g. 3‐month effectiveness).
Secondary outcomes
1. Adverse outcomes: any unexpected or unpredicted events related to the intervention, especially the serious adverse events leading to discontinuation of treatment.
2. The association between the effects mentioned above and type, wavelengths, energy doses, usage and course of the lasers.
Search methods for identification of studies
For the identification of studies included or considered for this review, detailed search strategies will be developed for each database searched. These will be based on the search strategy developed for MEDLINE but revised appropriately for each database to take account of differences in controlled vocabulary and syntax rules. The search strategy for MEDLINE via OVID is presented in Appendix 3.
Electronic searches
The following electronic databases will be searched.
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Cochrane Oral Health Group's Trials Register (to date; see Appendix 1)
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The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, current issue) (see Appendix 2)
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MEDLINE via OVID (1950 to present) (see Appendix 3)
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EMBASE via OVID (1980 to present) (see Appendix 4)
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CINAHL via EBSCO (1980 to present) (see Appendix 5)
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LILACS via BIREME Virtual Health Library (1982 to present) (see Appendix 6)
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OpenSIGLE (1990 to 2005) (see Appendix 7)
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China National Knowledge Infrastructure (CNKI) (1979 to present)
Searching other resources
The reference lists of all articles retrieved by the search will be checked to identify additional relevant trials. All available conference proceedings through electronic abstracting services such as IADR.com, ZETOC, and Web of Science will be searched for relevant RCTs. Researchers in the field will be contacted to identify unpublished studies, and the International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov will be searched for ongoing trials:
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IADR.com (to date) (see Appendix 8)
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ZETOC (1993 to present) (see Appendix 9)
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Web of Science Conference Proceedings (1990 to present) (see Appendix 10)
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ICTRP (to date) (see Appendix 11)
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ClinicalTrials.gov (to date) (see Appendix 12)
The following journals will be handsearched.
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Lasers in Medical Science (January 2001 to July 2011)
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Photomedicine and Laser Surgery (January 2001 to July 2011)
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Periodontology (January 2001 to July 2011)
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Journal of Oral Laser Application (January 2001 to July 2011)
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West China Journal of Stomatology (January 2001 to July 2011)
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Chinese Journal of Stomatology (January 2001 to July 2011)
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Journal of Practical Stomatology (January 2001 to July 2011)
There will be no restrictions on language. Non‐English language papers will be translated.
Data collection and analysis
Selection of studies
Two review authors will assess the titles and the abstracts of studies identified in the searches independently and in duplicate. Full copies of all relevant and potentially relevant trials, those appearing to meet the inclusion criteria, or for which there may be insufficient data in the title and abstract to make a clear decision, shall be obtained. The full text papers will be assessed independently and in duplicate, and any disagreement on the eligibility of trials shall be resolved through discussion and consensus. All potentially relevant studies that failed to meet the eligibility criteria will be excluded and the reasons for their exclusion noted in the 'Characteristics of excluded studies' section of the review. Studies considered suitable for inclusion will be described in the 'Characteristics of included studies' section.
Data extraction and management
Two review authors will extract data from the included studies independently and in duplicate.
Assessment of risk of bias in included studies
Two review authors will assess the included studies following the domain‐based evaluation described in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (Higgins 2011). Any disagreements between the review authors discussed and resolved.
It is a two‐part tool addressing the following domains.
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Sequence generation
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Allocation concealment
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Blinding (of participants, personnel and outcome assessors)
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Incomplete outcome data
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Selective outcome reporting
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Other sources of bias
Each domain in the tool includes one or more specific entries in a ‘Risk of bias’ table. Within each entry, the first part of the tool describes what was reported to have happened in the study, in sufficient detail to support a judgement about the risk of bias. The second part of the tool assigns a judgement relating to the risk of bias for that entry. This is achieved by assigning a judgement of ‘Low risk’ of bias, ‘High risk’ of bias, or ‘Unclear risk’ of bias.
After taking into account any additional information provided by the authors of the trials, studies will be grouped into the following categories.
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Low risk of bias (plausible bias unlikely to seriously alter the results) for all key domains.
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Unclear risk of bias (plausible bias that raises some doubt about the results) if one or more key domains were assessed as unclear.
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High risk of bias (plausible bias that seriously weakens confidence in the results) if one or more key domains were assessed to be at high risk of bias.
A risk of bias table will be completed for each included study and the results will also be presented graphically.
Measures of treatment effect
We will compare specific types of lasers employed in dentistry (e.g. Nd:YAG, CO2, He‐Ne or GaAlAs (diode) lasers, with different radiation parameters) for treatment of hypersensitivity with other in‐office treatment alternatives (i.e. dentine sealing agents, fluoride varnishes, etc), placebo or no treatment. When outcomes are dichotomous (e.g. presence of pain) we will use risk ratios and when outcomes are continuous (e.g. intensity of pain) we will use the mean difference, with respective 95% confidence intervals.
Unit of analysis issues
If outcomes are reported both at baseline and at follow‐up or at trial endpoints, we will extract both the mean change from baseline and the standard deviation of this mean for each treatment group, as well as the same for endpoint data.
If count data are reported in trials, we will extract the total number of events in each group. We will also record the total number of participants in each group. If this information is not available, we will attempt to extract alternative summary statistics such as rate ratios and confidence intervals, if available. If count data are presented as dichotomous outcomes, we will extract the number of participants in each intervention group and the number of participants in each intervention group who experienced at least one event.
If outcomes from cross‐over trials are considered (where neither carryover nor treatment effects are a problem) then analysis of a continuous two‐intervention cross‐over trial will be through a paired t test, provided the mean and standard deviation (or standard error) between the experimental and control groups are provided (Higgins 2011).
Data from split‐mouth studies will be combined with those of parallel studies.
Dealing with missing data
The original trial investigators will be contacted to request missing data if possible.
Assessment of heterogeneity
We will assess clinical heterogeneity using the I2 statistic, where values over 50% indicate substantial to considerable heterogeneity (Higgins 2011).
Assessment of reporting biases
We will address publication bias using a funnel plot if we have at least 10 included studies.
Data synthesis
We will pool data using a fixed‐effect model if there is no significant heterogeneity (I2 ≤ 50%) or if there are less than four studies in an analysis. If there is significant heterogeneity (I2 > 50%) or if there are more than four studies in an analysis then we will pool data using a random‐effects model.
In case of cross‐over data, all measurements (means, standard deviation or standard error) from the experimental and control interventions will be taken and analysed as in a parallel group trial.
The data from split‐mouth studies will also be involved in meta‐analysis.
Subgroup analysis and investigation of heterogeneity
If sufficient data are available, a subgroup analysis will be conducted based on the type of lasers.
Sensitivity analysis
We will conduct sensitivity analyses to investigate the robustness of the results for the primary outcomes by evaluating outcomes in trials with low risk of bias versus those with high risk or unclear risk of bias. We will also undertake sensitivity analyses if trials report dropout rates of 10% or greater, to ascertain differences in outcomes of intention‐to‐treat (ITT) analysis and analysis of completers.
