Non-pharmacological interventions for reducing mental distress in patients undergoing dental procedures: Systematic review and meta-analysis

Abstract

Objectives

This meta-analysis investigates the efficacy of non-pharmacological interventions in adults undergoing dental procedures under regional or general anesthesia compared to standard care alone or an attention control group on the reduction of mental distress, pain, and analgesic use.

Data sources

To identify relevant papers a comprehensive literature search was carried out in MEDLINE, CENTRAL, Web of Science, and PsycINFO (last search August 2017). Additionally, lists of references of relevant articles and previous reviews were checked. ProQuest Dissertations and Theses Full Text Database was screened to identify any unpublished material.

Study selection

A total of 29 eligible randomized controlled trials were included, comprising a total of 2.886 patients. Included trials investigated the effects of hypnosis, enhanced information, relaxation, music, or cognitive-behavioral approaches including distraction.

Results

Random effects meta-analyses revealed significant positive treatment effects on the reduction of mental distress (g = 0.58, CI 95% [0.39; 0.76]). Effects on pain relief (g = 0.00, CI 95% [−0.28; 0.28]) and the reduction of analgesic use (g = 0.26, CI 95% [−0.22; 0.73]) were not significant. Because effects on mental distress were substantially heterogeneous, subgroup analyses were run yielding significantly larger effects for studies with low risk of bias compared to studies with high or unclear risk of selection and attrition bias. No significant differences appeared between various types of non-pharmacological interventions.

Conclusions

In summary, benefits of non-pharmacological interventions on reducing mental distress were demonstrated with largest effects being shown for hypnosis. However, further high quality trials are needed to strengthen the promising evidence.

Clinical significance

This systematic review and meta-analysis indicated that non-pharmacological interventions may be beneficial for reducing mental distress in patients undergoing dental procedures and could thus be considered as valuable adjunct to standard care.

Introduction

Even though dental treatment is largely painless under local or general anesthesia by now, it is commonly perceived as an uncomfortable, threatening, and confusing situation. Hence, many patients experience fear or anxiety not only during invasive procedures. Sights, sounds, and smells associated with the dental clinic, injections, dental instruments, perceived lack of control and predictability, and (anticipated) pain result in patients’ mental distress [ ].

While many people experience anxiety and fear of going to a dental practitioner ranging from very mild to more severe manifestations, only a relatively small percentage of dental patients will have a clinically diagnosed condition of a specific (dental) phobia (e.g., according to the International Statistical Classification of Diseases and Related Health Problems 10th Revision [ICD-10]). Up to every fourth adult is reporting dental fears, whereas the point prevalence of clinically relevant dental phobia is estimated to be about 4% [ ]. Contemporary models hypothesize a continuum of situation-specific fear or anxiety experiences related to dental care, including those being considered as “normal,” those that contain only infrequent and insignificant fear/anxiety behaviors, and those that include more frequent or impairing fear/anxiety behaviors with complete avoidance of dental care [ ]. The most common way to measure dental anxiety is by using the Dental Anxiety Scale (DAS) [ ]. This questionnaire captures the possible continuum of dental anxiety also allowing for the identification of highly anxious patients.

Research suggests that the general dental practitioner is capable of treating adults with mild or moderate forms of dental anxiety effectively, while treatment of severe dental anxiety or even dental phobia often requires more specialist interventions, e.g., psychotherapy [ ]. In recent years, numerous non-pharmacological approaches have been developed to improve the handling of anxious patients during as well as before dental treatments [ ]. Primarily, those interventions aim at reducing mental distress in patients before and during dental procedures. Related indirect effects of reduced mental distress might be the reduction of pain and the facilitation of recovery after therapy since mental distress is known to impair post-operative treatment success of surgical, endodontic, or other dental procedures [ ].

Hence, non-pharmacological interventions could be considered as an adjunct to standard care and to “first-line treatment” such as pharmacological strategies such as pre-medication, sedation, or analgesia. There are several different approaches that can be used in the dental clinic or surgery in order to assist anxious patients. Existing techniques can be categorized into enhanced information, cognitive-behavioral interventions, hypnosis, relaxation procedures or music interventions [ ]. Enhanced information draws on the patient’s cognitive level to transmit sensory and/or procedural information before, during and after dental procedure. Cognitive-behavioral strategies focus on the reduction of dental anxiety through, e.g., distraction, sensory focusing, positive reinforcement, cognitive restructuring, or systematic desensitization. Relaxation techniques are described as teaching or instructing patients in, e.g., progressive muscle relaxation, guided imaginary, breath control, or autogenic training aim to induce relaxation and comfort [ ]. Hypnosis has a longstanding tradition in use during medical procedures. It is suggested to work mainly through two mechanisms: reducing distress and targeting patient expectancies with suggestions for positive outcomes [ ]. Music interventions have been used in different medical fields to meet patients’ psychological, physical, social and spiritual needs. Inherent elements of music are known to influence physiological and psycho-emotional responses in patients, e.g., arousing memory and association, stimulating imagery, evoking emotions, and promoting relaxation and distraction [ ].

Existing meta-analyses included only trials conducted before 2001 [ ] or focused exclusively on the efficacy of psychological treatments (cognitive-behavioral therapy and behavioral therapy) for severe levels of dental anxiety or dental phobia [ ]. Hence, the aim of the present systematic review and meta-analysis is to give a comprehensive overview of non-pharmacological interventions for patients with mild, moderate and severe levels of anxiety (excluding dental phobia) that are implementable in general dental practice before or during dental procedures. Moreover, we aim to quantify the efficacy of these approaches to reduce mental distress in patients undergoing dental procedures in comparison to standard care alone or to attention control groups.

Methods

Objectives, inclusion criteria, and methods have been pre-specified in a review protocol (registered in PROSPERO; June 28, 2016; www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42016041661 ).

Identification and selection of studies (PICOS)

Patients

Adult patients (18 years and older) undergoing dental procedures usually provided under general and regional anesthesia. Studies with children and adolescents were excluded.

Interventions

Any non-pharmacological intervention which is implemented before or during dental procedures in general dental practice.

Comparators

Eligible control groups were “treatment as usual” (defined as the standard dental care policy of the dental practice) and “attention control” groups (defined as providing the same amount of time and attention to the patients just as in the intervention group but without applying a specific therapeutic technique).

Outcomes

The included trials reported on at least one of the following outcomes measured via self- and/or observer reports: mental distress (i.e., anxiety, mood; primary outcome), pain, and medication (i.e., analgesic use; secondary outcomes).

Study design

We included randomized controlled trials (RCTs) only.

Search methods

We carried out electronic searches in the databases MEDLINE, CENTRAL, Web of Science, and PsycINFO (last search August 2017). The MEDLINE search strategy is shown in Supplementary Table 1. We adapted the strategy for Web of Science, Central and PsycINFO. Additionally, we checked lists of references of relevant articles and previous reviews. We further screened ProQuest Dissertations and Theses Full Text Database to identify any unpublished material. One author (SB) screened titles and abstracts of database records and retrieved full texts for eligibility assessment.

Data extraction and management

The following data were extracted from the included studies by using a pilot-tested data extraction form: characteristics of patients, intervention, control group, outcomes, bibliographic information, and effect size related data. Two raters (SB, JR) independently extracted the data; inter-rater disagreement was resolved through consensus. Study authors were contacted in case of missing information. If information on effect sizes was missing and could not be retrieved, data was approximated using different estimation methods (e.g., we estimated statistics from graphs without numerical data, set an effect size to zero if non-significant results were mentioned without reporting statistical parameters).

Assessing the risk of bias in included studies

We assessed risk of bias in the included studies by common markers of internal validity from the Cochrane Risk of Bias Tool [ ]. The risk of selection bias (sequence generation, allocation sequence concealment), the risk of reporting bias (selective outcome reporting), and the risk of performance bias (blinding of dentist and medical personnel) were assessed at study level, and the risk of detection bias (blinding of outcome assessors) as well as attrition bias (handling incomplete outcome data) at outcome level, respectively. Blinding of outcome assessors was assessed only for observer-reported outcomes, not for self-reported. Risk of bias assessment was conducted by two independent, previously trained raters (LH, JR). Disagreements were resolved through consensus with a third author (SK).

Summary measures

We calculated bias-corrected standardized mean differences (Hedges’ g) [ ]. An effect size of 0.5 thus indicates that the mean of the intervention group is half a standard deviation larger than the mean of the control group. The magnitude of Hedges’ g was interpreted within the same ranges as Cohen’s d, regarding 0.20, 0.50, and 0.80 as small, medium, and large effect sizes, respectively [ ]. For dichotomous outcomes, Log Odds Ratios were calculated and converted to Hedges’ g in order to pool across different effect size formats [ ]. If available, intention-to-treat data were used to calculate effect sizes.

Data synthesis

Comprehensive Meta-Analysis (CMA; Version 3.0; Biostat Inc.) was used to perform data analyses. Outcome data were meta-analyzed using a random-effects approach. The generic inverse variance method was applied with heterogeneity estimated using the DerSimonian-Laird method [ ]. Statistical heterogeneity between trials was assessed with χ 2 heterogeneity tests (Cochrane’s Q) and I 2 statistic [ ]. I 2 describes the percentage of the variability in effect estimates that is due to heterogeneity rather than chance, with values from 0 to 40% indicating no important heterogeneity, 30% to 60% moderate, 50% to 90% substantial, and 75% to 100% considerable heterogeneity, respectively [ ].

For multiple comparisons within a study we computed a combined effect defined as the mean effect size in that study with a variance adjusted by a correlation of 0.50 among the comparisons. If comparisons within one study were considered for different categories in the subgroup analyses (e.g., TAU and attention control), results of both comparisons were included as separate estimates [ ]. If multiple outcomes were reported within one outcome domain (e.g. two measures of anxiety), effect sizes were aggregated within domains for each unit of analysis and correlations between outcomes were set at 0.50 [ ].

Risk of bias across studies

We visually inspected funnel plots and run the Egger test [ ] to test for publication bias. Additionally, we used Duval and Tweedie’s trim and fill procedure to obtain an adjusted estimate of the treatment effect after the publication bias had been taken into account and to indicate how many missing trials have been imputed to correct for publication bias [ ].

Additional analyses

We conducted sensitivity analyses in order to test the robustness of findings, examining if meta-analytic results change when excluding outliers or approximated effect sizes. We further run exploratory subgroup analyses to explain statistical heterogeneity [ ].

Methods

Objectives, inclusion criteria, and methods have been pre-specified in a review protocol (registered in PROSPERO; June 28, 2016; www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42016041661 ).

Identification and selection of studies (PICOS)

Patients

Adult patients (18 years and older) undergoing dental procedures usually provided under general and regional anesthesia. Studies with children and adolescents were excluded.

Interventions

Any non-pharmacological intervention which is implemented before or during dental procedures in general dental practice.

Comparators

Eligible control groups were “treatment as usual” (defined as the standard dental care policy of the dental practice) and “attention control” groups (defined as providing the same amount of time and attention to the patients just as in the intervention group but without applying a specific therapeutic technique).

Outcomes

The included trials reported on at least one of the following outcomes measured via self- and/or observer reports: mental distress (i.e., anxiety, mood; primary outcome), pain, and medication (i.e., analgesic use; secondary outcomes).

Study design

We included randomized controlled trials (RCTs) only.

Search methods

We carried out electronic searches in the databases MEDLINE, CENTRAL, Web of Science, and PsycINFO (last search August 2017). The MEDLINE search strategy is shown in Supplementary Table 1. We adapted the strategy for Web of Science, Central and PsycINFO. Additionally, we checked lists of references of relevant articles and previous reviews. We further screened ProQuest Dissertations and Theses Full Text Database to identify any unpublished material. One author (SB) screened titles and abstracts of database records and retrieved full texts for eligibility assessment.

Data extraction and management

The following data were extracted from the included studies by using a pilot-tested data extraction form: characteristics of patients, intervention, control group, outcomes, bibliographic information, and effect size related data. Two raters (SB, JR) independently extracted the data; inter-rater disagreement was resolved through consensus. Study authors were contacted in case of missing information. If information on effect sizes was missing and could not be retrieved, data was approximated using different estimation methods (e.g., we estimated statistics from graphs without numerical data, set an effect size to zero if non-significant results were mentioned without reporting statistical parameters).

Assessing the risk of bias in included studies

We assessed risk of bias in the included studies by common markers of internal validity from the Cochrane Risk of Bias Tool [ ]. The risk of selection bias (sequence generation, allocation sequence concealment), the risk of reporting bias (selective outcome reporting), and the risk of performance bias (blinding of dentist and medical personnel) were assessed at study level, and the risk of detection bias (blinding of outcome assessors) as well as attrition bias (handling incomplete outcome data) at outcome level, respectively. Blinding of outcome assessors was assessed only for observer-reported outcomes, not for self-reported. Risk of bias assessment was conducted by two independent, previously trained raters (LH, JR). Disagreements were resolved through consensus with a third author (SK).

Summary measures

We calculated bias-corrected standardized mean differences (Hedges’ g) [ ]. An effect size of 0.5 thus indicates that the mean of the intervention group is half a standard deviation larger than the mean of the control group. The magnitude of Hedges’ g was interpreted within the same ranges as Cohen’s d, regarding 0.20, 0.50, and 0.80 as small, medium, and large effect sizes, respectively [ ]. For dichotomous outcomes, Log Odds Ratios were calculated and converted to Hedges’ g in order to pool across different effect size formats [ ]. If available, intention-to-treat data were used to calculate effect sizes.

Data synthesis

Comprehensive Meta-Analysis (CMA; Version 3.0; Biostat Inc.) was used to perform data analyses. Outcome data were meta-analyzed using a random-effects approach. The generic inverse variance method was applied with heterogeneity estimated using the DerSimonian-Laird method [ ]. Statistical heterogeneity between trials was assessed with χ 2 heterogeneity tests (Cochrane’s Q) and I 2 statistic [ ]. I 2 describes the percentage of the variability in effect estimates that is due to heterogeneity rather than chance, with values from 0 to 40% indicating no important heterogeneity, 30% to 60% moderate, 50% to 90% substantial, and 75% to 100% considerable heterogeneity, respectively [ ].

For multiple comparisons within a study we computed a combined effect defined as the mean effect size in that study with a variance adjusted by a correlation of 0.50 among the comparisons. If comparisons within one study were considered for different categories in the subgroup analyses (e.g., TAU and attention control), results of both comparisons were included as separate estimates [ ]. If multiple outcomes were reported within one outcome domain (e.g. two measures of anxiety), effect sizes were aggregated within domains for each unit of analysis and correlations between outcomes were set at 0.50 [ ].

Risk of bias across studies

We visually inspected funnel plots and run the Egger test [ ] to test for publication bias. Additionally, we used Duval and Tweedie’s trim and fill procedure to obtain an adjusted estimate of the treatment effect after the publication bias had been taken into account and to indicate how many missing trials have been imputed to correct for publication bias [ ].

Additional analyses

We conducted sensitivity analyses in order to test the robustness of findings, examining if meta-analytic results change when excluding outliers or approximated effect sizes. We further run exploratory subgroup analyses to explain statistical heterogeneity [ ].

Results

Study selection

We screened a total of 3.424 records and finally included N = 29 RCTs in the meta-analysis. Fig. 1 contains the flow chart of the study selection process.

Fig. 1
Flowchart of identification, screening, and assessing studies for inclusion eligibility.

Study characteristics

All included studies were published in English between 1979 and 2017 ( Table 1 ). Among the primary studies, 14 were from USA, three from China/Taiwan, two each from Germany, Korea, and Turkey, and one each from Spain, Sweden, United Kingdom, Saudi Arabia, Malaysia, and the Netherlands, respectively.

Table 1
Characteristics of the included studies.
Study Patients’ level of anxiety # Dental procedure Description of non-pharmacological intervention n Description of control group n Outcomes
Biggs 2003 [ ] DAS M = 7.9
high: 9.6%
dental procedure (1) relaxation: deep diaphragmatic breathing, 10–30 min* before procedure 88 TAU 90 Mental distress (anxiety)
(2) cognitive intervention: focused attention on a neutral part of body, 10–30 min before procedure 94
Choi 2015 [ ] DAS M = 10.8 third molar surgery enhanced information: basic information and slideshow presentation including simple illustrations, audio and visual cues, before procedure 25 TAU (incl. basic information) 26 Mental distress (anxiety)
Pain intensity
Colorado-Bonnin 2006 [ ] third molar extraction enhanced information: prior to extraction, instructions from a surgeon about the postoperative course after extraction with a written text containing postoperative instructions, before procedure 45 TAU 46 Pain intensity
Corah 1979 [ ] Class II amalgam restoration (1) relaxation: standard relaxation instructions, before and during procedure 20 TAU 20 Mental distress (discomfort self/dentist)
(2) distraction: playing a video ping pong game, before and during procedure 20
Corah 1981 [ ] Class II amalgam restoration relaxation: standard relaxation instructions, 25 min, before and during procedure 20 (1) TAU 20 Mental distress (discomfort)
(2) AttCG: listening to a story about traveling in Vermont 20
Croog 1994 [ ] periodontal surgery cognitive intervention: repeated psychological messages, designed for short-term cognitive reshaping, 8 min, before procedure 11 TAU 9 Mental distress (anxiety, distress)
Pain intensity
Medication (analgesics)
DeNitto 2012 [ ] DAS M = 5.9 endodontic treatment distraction: relaxation movie via video eyewear, 90 min, during procedure 30 TAU 30 Mental distress (anxiety)
Eitner 2011 [ ] dental-implant surgery hypnosis: audio pillow with hypnosis text and relaxation music, 66 min, during procedure 44 AttCG: audio pillow without hypnosis 38 Mental distress (anxiety)
Enqvist 1997 [ ] third molar extraction hypnosis: daily listening a hypnosis tape containing a hypnotic relaxation induction, 20 min, 6–8 days before procedure 33 TAU 36 Mental distress (anxiety)
Medication (analgesics)
Gan 2017 [ ] DAS M = 12.5 restorative treatment combined psychological intervention: psychoeduaction + relaxation + modeling technique: 45 min, before procedure 15 TAU 15 Mental distress (anxiety)
Gazal 2016 [ ] tooth removal enhanced information: video-tape with information demonstration of ideal painless procedure, before procedure 29 TAU 29 Mental distress (anxiety)
Getka 1992 [ ] DAS M = 15.1
high: 100%
Class 1 or Class 2 carious lesion (1) behavioral intervention: 50 min, 6 sessions, before procedure 10 TAU 10 Mental distress (anxiety)
Pain intensity (pain experienced)
(2) cognitive-behavioral intervention: 50min, 6 sessions, before procedure 11
Ghoneim 2000 [ ] STAI-S M = 31.9 third molar surgery hypnosis: daily listening a hypnosis-tape, 20 min, 6–8 days before procedure (see Enqvist 1997) 30 TAU 30 Mental distress (anxiety)
Pain intensity
Medication (analgesics, number of vicodin/ibuprofen tablets)
Johnson 1992 [ ] DAS M = 11.5 tooth removal (1) enhanced information: listen to an audio tape recording of general surgical information, 6 min, before procedure 25 TAU 25 Mental distress (relaxation, anxiety)
(2) relaxation: listen to a relaxation tape, before procedure 25
(3) enhanced information + relaxation: audio tape + relaxation information, before procedure 25
Katcher 1984 [ ] oral surgery (elective extraction) (1) distraction: contemplation of an aquarium/poster, 40 min, before procedure 8 TAU 10 Mental distress (comfort)
(2) distraction + hypnosis: contemplation of an aquarium/poster + hypnosis, before procedure 8
Kazancioglu 2015 [ ] DAS M = 11.2 third molar extraction (1) enhanced information: basic information given verbally with details of operative procedures and recovery, before procedure 95 TAU 103 Mental distress (anxiety)
Pain intensity
(2) enhanced information: basic information and a movie of a man undergoing third molar surgery, 5 min, before procedure 102
Kazancioglu 2017 [ ] dental implant surgery (1) enhanced information: basic information given verbally with details of operative procedures and recovery, before procedure 20 TAU 20 Mental distress (anxiety)
Pain intensity
(2) enhanced information: basic information and a video including a patient undergoing the dental procedure (2 min), before procedure 20
Kim 2011 [ ] DAS M = 13.3 third molar extraction music: favorite songs selected by the patient presented via headset, 23 min, during procedure 106 TAU 113 Mental distress (anxiety)
Pain intensity
Lahmann 2008 [ ] STAI-S M = 41.9
high: 17.2%
restorative treatment, only filling (1) relaxation: brief (functional) relaxation, during procedure 29 TAU 30 Mental distress (anxiety)
(2) music: during procedure 28
Lai 2008 [ ] STAI-S M = 50.2
high: 100%
root canal treatment music: selected sedative (piano) music presented via headphones, 60 min, during procedure 22 AttCG: headphones without music 22 Mental distress (anxiety)
Litt 1993 [ ] third molar extraction (1) relaxation: monitoring the extent of relaxation by means of a galvanic skin response apparatus, 60 min, before procedure 19 TAU 17 Mental distress
(2) relaxation + self-efficacy enhancement, 60 min, before procedure 19
Litt 1995 [ ] third molar extraction (1) relaxation (see Litt 1993), 20 min, before procedure 46 TAU (incl. oral premed) 46 Mental distress
(2) cognitive-behavioral intervention: relaxation + self-efficacy enhancement + needle desensitization, 20 min, before procedure 45
Logan 1995 [ ] endodontic treatment (1) cognitive intervention: sensory focusing (instructing to pay attention to the physical sensations in the mouth), 1 min, before procedure 83 TAU 83 Pain intensity
(2) enhanced information: procedural information (brief explanation and description of endodontic treatment), 2 min, before procedure 83
(3) cognitive intervention + enhanced information: combination of (1) and (2), 3 min, before procedure 82
Ng 2004 [ ] oral surgery (1) enhanced information: details of the dental procedures, before procedure 48 TAU (incl. basic information) 48 Mental distress (anxiety)
(2) enhanced information: details of the expected recovery, before procedure 48
(3) enhanced information: combination of (1) and (2), before procedure 48
Robertson 1991 [ ] DAS M = 10.7 emergency oral surgery, extraction behavioral treatment program: videotape with information about dental fear and behavioral interventions effective in its reduction, 25 min, before procedure 20 TAU 20 Mental distress (anxiety)
Pain intensity
Ross 1981 [ ] third molar extraction hypnosis: hypnosis tape with suggestions for bleeding and edema control, before procedure 9 AttCG: tape with information about third molars 9 Medication (analgesics)
Tanja-Dijkstra 2017 [ ] DAS M = 13.0 tooth filling and/or extraction (1) virtual reality distraction: urban environment to be actively explored by thumbstick controller, during procedure 22 TAU 28 Mental distress
Pain intensity
(2) virtual reality distraction: coastal environment to be actively explored by thumbstick controller, during procedure 20
Van Wijk 2008 [ ] third molar extraction enhanced information: detailed information about third molar removal in a separate consultation with a surgeon, before procedure 21 TAU 29 Mental distress (anxiety)
Pain intensity
Yi-Yueh 2014 [ ] root canal treatment (1) music: Chinese music presented via loudspeaker 60 TAU 30 Mental distress (anxiety)
Pain intensity
(2) music: Western classic music (Mozart K.448) presented via loudspeaker 60
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Jun 17, 2018 | Posted by in General Dentistry | Comments Off on Non-pharmacological interventions for reducing mental distress in patients undergoing dental procedures: Systematic review and meta-analysis
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