Skip to main content
NCBI home page
International Dental Journal logoLink to International Dental Journal
. 2020 Oct 28;68(2):77–83. [Article in French] doi: 10.1111/idj.12330

Third molor extractions among Australian adults: findings from the 2013 National Dental Telephone Interview Survey

Kamal Hanna 1,*, Paul Sambrook 2, Jason M Armfield 1, Lisa Jamieson 1, David S Brennan 1
PMCID: PMC9378918  PMID: 29034476

Introduction

Australia has one of the highest rates in the world of hospitalisation for third molar extractions1 which might suggest that third molars are removed prophylactically. Third molar extractions are performed by an experienced dentist or an oral surgery specialist. In Australia, the majority of dentists work in the private sector2 while the majority of oral and maxillofacial surgeons work in both private and public sectors3. Current figures indicate that 55% of Australians have ‘general treatment’ private health insurance4 which covers the surgeon’s fees for third molar surgery, while 47% of Australians have ‘hospital policy’ insurance, which covers the hospitalisation and anaesthetist’s fees for third molar surgery5. While third molar patients eligible for public dental services face a long waiting list for consultation and another waiting list for receiving third molar surgery6, privately insured third molar patients face almost no waiting list to receive third molar extraction. Although the Australian Dental Association7 does not refute or support prophylactic third molar removal, it recommends leaving the decision to patients and their dentist. Considering that clinics are often over-booked8, third molar patients might be hindered in being adequately informed9. Additionally, evidence from a US study shows that privately insured patients are more likely to adhere to their dentist’s recommendation for prophylactic third molar extraction10. Furthermore, some dentists are encouraging their patients to use their dental insurance because they have paid for it and to avoid future out-of-pocket payments11. Accordingly, it might be argued that the possession of dental insurance might be associated with a higher number of third molar extractions received.

Third molar surgery is the most common oral surgical procedure12 and might be performed for several reasons: to eliminate a local problem, such as pericoronitis; for untreatable decay; for periodontitis; association with pathology; facilitating orthodontic treatment; or prophylactically to prevent future problems10. The current evidence does not support the prophylactic removal of asymptomatic disease-free third molars13., 14., with suggestions made for more research to evaluate the impact of retention versus extraction of asymptomatic third molars on patient-reported outcomes in the short term and long term14. The lack of evidence that supports prophylactic third molar extraction results in national guidelines in countries, such as the UK15 which prohibit the prophylactic extraction of asymptomatic disease-free impacted third molars. However, in Australia, it is argued that such guidelines are economically driven and will defer the problem16. Receiving multiple third molar extractions at a very short interval might suggest their prophylactic extraction. Therefore, identifying whether single versus multiple third molar extraction is associated with self-rated oral health might provide some evidence, in the short term (less than 1 year), from a population-based study, towards the benefit/risk for prophylactic third molar extractions.

Third molar surgery might be performed across a wide spectrum of age. Some dentists recommend their young adult patients to have their third molars prophylactically removed to obtain ‘peace of mind’ from developing future infection17. In addition, it is argued that age is a risk factor for postoperative complications18 leading to a prolonged recovery19. In contrast, others argue that the occurrence of these complications is attributed to the experience of the surgeon and the use of tobacco by patients20. Although Tolstunov21 recommends the extraction of both symptomatic and asymptomatic third molars at 16–25 years of age, Santosh20 argues against the use of age as a reasonable justification for performing prophylactic third molar removal. In addition, previous studies indicate that the number of third molar extractions is significantly associated with prolonged recovery19 because of increased surgical trauma. Development of problems, such as infection before the surgery and/or postoperative complications in older age groups will have a reflection on the number of days absent from work/school because of dental problems. Therefore, further exploring the association between the age range in which third molar extractions are received and number of days absent from work/school because of dental problems will help in consolidating the current evidence and optimising third molar extraction decision-making.

The aim of this study was to identify, over the past 12 months, whether: (i) having dental insurance is associated with a higher number of third molar extractions; (ii) receiving single versus multiple third molar extractions is associated with self-rated oral health in the short term; (iii) receiving third molar extractions when 18–25 years of age versus older than 25 years of age is associated with a fewer number of days absent from work/school because of dental problems.

Methodology

Data sources and ethical approval

This study utilised data from the 2013 National Dental Telephone Interview Survey (NDTIS), which is a random representative sample of residents of Australia, 5 years of age and over, who reside in a household that has a telephone line. Data were collected from June 2013 to March 2014. Only records representing adults 18 years of age and over were included in the current analysis. The 2013 NDTIS received ethical approval from the University of Adelaide Human Research Ethics Committee (HS-2013-014). The University of Adelaide Human Research Ethics Committee adheres to the World Medical Association Declaration of Helsinki, the Australian Code for the Responsible Conduct of Research 2007 and the National Health and Medical Research Council (NHMRC) guidelines. The targeted households were posted an approach letter 10 days before the interview. The approach letter explained the purpose of the study, how the households were selected, that participation is voluntary, what participation involves and that the participants’ identity will be kept confidential. In the interview, the interviewer explained the study again to the target person to obtain verbal consent before proceeding to the questionnaire. If the target person agreed to participate, the interviewer asked them a series of questions. If the target person declined to participate, this was recorded as a refusal outcome.

Sampling method

The 2013 NDTIS sampled Australia’s residents using an overlapping dual-sample frame design, targeting residents in households that have a telephone line. The first sampling frame comprised sampling of households listed on the Electronic White Pages obtained from ‘Australia on Disc, 2012’ supplied by the United Directory System (Sydney, NSW, Australia). Records from this frame were sampled using a two-stage stratified random sampling approach, in which records were stratified according to state/territory then according to capital city or rest of the state. A specified sampling fraction was used for selecting records from each substratum. The initial telephone contact was with an adult 18 years of age or over. To account for residential households that were not listed on the Electronic White Pages, a second sampling frame was used that comprised 20,000 randomly generated mobile telephone numbers supplied by Sampleworx (Artarmon, NSW, Australia). The records selected from the mobile sampling frame were not stratified because of the lack of geolocation before establishing the initial contact. The sampling methods resulted in 6,340 responses from adults 18 years of age and over with an average response rate of 34.4%. The 2013 NDTIS data were checked for quality and weighted22.

Variables

The telephone interview asked participants to provide the number of dental extractions they had received over the past 12 months. The question why such extractions were performed was then asked, for example, wisdom teeth, orthodontic treatment, periodontal disease, etc. Data for this analysis were included if a response of ‘yes’ was provided for the question pertaining to third molar extraction only. A dichotomous variable was created for multiple third molar extractions, based on the number of third molar extractions received. Other variables included participants’ sociodemographic details (age in years, gender, total annual household income and highest level of education), dental insurance status and self-rated oral health (a global item with responses ranging from 1 for ‘poor’ to 5 for ‘excellent’). Participants were asked ‘In the last 12 months, how many days have you stayed away from work/place of study for more than half the day because of any dental problems you had?’.

Data analysis

Data analysis was conducted using the complex samples module23 in SPSS statistics for Windows v. 23.0 (Armonk, NY, USA)24. A specified sampling plan was provided by the 2013 NDTIS data custodian to account for the complex sampling design. The selected subpopulation was participants who responded ‘yes’ to ‘had third molar extraction’ in the past 12 months. Using the complex sample module, estimates of population size with standard error (SE) for these estimates were obtained. Generalised linear models were used to identify associations between: (i) dental insurance and third molar extractions; (ii) single or multiple third molar extraction with self-rated oral health (in the short term) and; (iii) age (18–25 years versus 26+ years) and days absent from school/work because of dental problems.

Results

The unweighted count for those who responded ‘yes’ to third molar extraction was 120 participants, representing a total population of 440,026.6 (SE = 53,722.7) with an estimated prevalence of 25.6% (SE = 2.7%) among those who received dental extractions over the past 12 months. Most of those who received a third molar extraction were in the 18–25 years’ age category (63.0%, SE = 5.4), with a higher proportion of these being female (56.0%, SE = 6.0%) (Table 1). A higher proportion of those reporting a third molar extraction held a tertiary qualification (73.9%, SE = 5.4%) and were living in households with a total income of ≥$60,000 annually (58.3%, SE = 6.4%). Just over half of respondents reporting third molar extractions did not have dental insurance (52.6, SE = 6.2%). Around 60% of participants had received multiple third molar extractions during the past 12 months (SE = 5.8%).

Table 1.

Subpopulation characteristics of those who received third molar extraction

Population size Unweighted count (n = 120) Estimate N% (SE)/95% CI
Estimate SE
Age group
18–25 years 277,359.3 46,194.5 63.0 (5.4)
≥26 years 162,667.3 25,271.8 37.0 (5.4)
Gender
Male 193,656.3 33,314.8 44.0 (6.0)
Female 246,370.3 40,351.3 56.0 (6.0)
Had a tertiary qualification
No 114,747.5 27,024.5 26.1 (5.4)
Yes 325,279.0 44,372.9 73.9 (5.4)
Household income
<$60,000 153,921.7 31,122.5 41.7 (6.4)
≥$60,000 215,321.4 33,631.4 58.3 (6.4)
Whether have private dental insurance
Yes 203,138.7 35,145.6 47.4 (6.2)
No 225,593.5 38,329.0 52.6 (6.2)
Single or multiple third molar extraction
Single third molar extraction 170,993.3 29,231.7 39.1 (5.8)
Multiple third molar extraction 265,811.4 43,244.1 60.9 (5.8)
Self-rated oral health
Poor 23,299.6 11,611.3 5.3 (2.6)
Fair 51,650.8 20,624.7 11.7 (4.4)
Good 111,623.2 28,988.1 25.4 (5.6)
Very good 198,538.3 33,979.6 45.1 (6.1)
Excellent 54,914.7 16,060.2 12.5 (3.5)
Total 440,026.6 53,722.7 100.0 (0.0)
Mean number of days absent 2.1 0.4 1.3–2.9
Open in a new tab

Estimate (standard error), in %, or 95% confidence interval.

Dental insurance and low education status were associated with a higher number of third molar extractions when adjusted for gender and annual household income in multivariable modelling (Table 2). Each year increase in age was associated with a lower number of third molar extractions received. After adjusting for age, gender, income, education and dental insurance status, single versus multiple third molar extraction was not associated with self-rated oral health in the short-term (Table 3).

Table 2.

Complex samples general linear regression model for the number of third molar extractions received in the past 12 months among Australian adults*

Parameter Estimate 95% Confidence interval P-value
Lower Upper
(Intercept) 2.195 1.483 2.908 <0.01
Had a tertiary qualification
No 1.217 0.546 1.888 <0.01
Yes 0.000†
Have private dental insurance
Yes 0.972 0.486 1.458 <0.01
No 0.000†
Gender
Male 0.377 −0.267 1.020 0.251
Female 0.000†
Age (years) −0.027 −0.045 −0.009 0.003
Total household income 0.000 −0.058 0.059 0.990
Open in a new tab

Subpopulation: had extraction for wisdom teeth = yes.

*

Model: number of third molar extractions in the last 12 months = (Intercept) + had a tertiary qualification + dentally insured + gender + age (years) + household income.

†

Set to zero because this parameter is redundant (reference category).

Table 3.

Complex samples general linear model for self-rated oral health among Australian adults who received third molar extractions in the past 12 months*

Parameter Estimate 95% Confidence interval P value
Lower Upper
(Intercept) 3.20 2.40 4.00 0.013
Gender
Male 0.12 −0.34 0.59 0.604
Female 0.000†
Had a tertiary qualification
No −0.69 −1.29 −0.10 0.022
Yes 0.000†
Have private dental insurance
Yes 0.45 −0.07 0.97 0.088
No 0.00†
Multiple third molar extractions
No −0.25 −0.76 0.25 0.325
Yes 0.000†
Age (years) 0.00 −0.02 0.01 0.901
Total household income 0.04 −0.02 0.10 0.227
Open in a new tab

Subpopulation: had extraction for wisdom teeth = yes.

*

Model: self-rated dental health = (Intercept) + gender + had a tertiary qualification + dentally insured + received multiple third molar extractions + age (years) + household income.

†

Set to zero because this parameter is redundant (reference category).

Receiving third molar surgery when 18–25 years of age versus older age groups was not significantly associated with work/school absenteeism when adjusted for in multivariable modelling (Table 4). However, the number of third molar extractions was significantly associated with the number of days absent from work/school because of dental problems.

Table 4.

Complex samples general linear model for the days absent from work/school because of dental problems among Australian adults who received third molar extractions in the past 12 months*

Parameter Estimate 95% Confidence interval P value
Lower Upper
(Intercept) −0.23 −5.89 5.42 0.007
Have private dental insurance
Yes −0.14 −2.08 1.81 0.888
No 0.000†
Gender
Male −0.49 −2.24 1.25 0.579
Female 0.000†
Had a tertiary qualification
No −2.51 −4.80 −0.23 0.031
Yes 0.000†
Age group
18–25 years 0.48 −1.37 2.33 0.608
≥26 years 0.000†
Total household income 0.03 −0.19 0.25 0.786
Third molar extraction count 1.10 0.26 1.94 0.011
Self-rated oral health 0.03 −0.82 0.89 0.942
Open in a new tab

Subpopulation: had extraction for wisdom teeth = yes.

*

Model: number of days missed from work/school/study for more than half a day because of dental problems = (Intercept) + dentally insured + gender + had a tertiary qualification + age group + household income + third molar extractions count + self-reported dental health.

†

Set to zero because this parameter is redundant (reference category).

Discussion

Our findings suggest that having dental insurance was associated with an increased number of third molar extractions in the past 12 months among Australian dentate adults 18 years of age and over. This indicates that dentally insured adults might be subjected to over-management as there was no significant association between the number of third molar extractions and self-rated oral health. Although number of days absent from work/school because of dental problems was associated with number of third molar extractions, they were not associated with receiving third molar extraction when 18–25 years of age versus older age group.

The association observed between dental insurance status and third molar extractions might be a result of the enabling effects of having dental insurance. The pattern of the association between dental insurance and third molar extractions was in contrast to what has been previously reported for extractions, in general, in the Australian population25. The observed difference might be a result of the reason for extraction, which differs between third molars and other teeth. Extractions other than third molar or for orthodontic treatment are mainly related to untreatable decay or advanced periodontal diseases26 which are known to be less prevalent among the dentally insured27. While a previous Australian study indicates that hospitalisation for third molar extraction is associated with socio-economic status28, we observed that dental insurance was associated with a higher number of third molar extractions independent of where the surgery was performed. Our findings suggest that, on average, having dental insurance was associated with receiving extraction of one more third molar in comparison with the non-insured over the past 12 months. Evidence from a national dental survey in Australia indicated that dentally insured subjects make more visits and purchase prophylactic dental treatments at check-ups29. This behaviour might be applied to third molar extractions1. Despite variations in insurance cover for third molar extraction according to policy selected and type of health and dental cover chosen, some researchers suggest that dental insurance status makes most patients decide on third molar prophylactic extraction10. In fact, some clinicians recommend that their patients use their dental insurance cover as they have already paid for it11. Some scholars recommend prophylactic third molar extraction when general anaesthesia is used if they are not associated with an anatomical risk30. In addition, Steed31 recommends prophylactic removal of the opposing third molar simultaneously in the same operation, if there are no anatomic risks, to avoid future super-eruption. Private health insurance is reported to have an association with increased utilisation of health-care services in other countries, such as the USA32 in general and at the dental service-level33 after adjusting for health status.

Multiple third molar extractions were more prevalent in our sample compared with single third molar extractions. Single versus multiple third molar extraction was found not to have a significant association with self-rated oral health in the short term. This adds to the ongoing argument regarding third molar prophylactic removal13., 14.. These findings might suggest the need to provide third molar patients with pre-consultation evidence-based resources and to investigate the association with third molar decision-making and decision-outcomes (currently in progress34) as previous studies indicate that clinics are overbooked8 which might result in patients being inadequately informed9.

The observed association between the number of third molar extractions and the number of days unable to work/attend school as a result of dental problems, which served as a proxy for third molar extraction recovery, is consistent with previous reports and is explained by the surgical trauma35 and consequent prolongation of the recovery period19. It has been argued that performing prophylactic third molar extraction among those in younger age groups is not justified owing to the increased risk of developing postoperative dry socket, which was found to be associated with lack of clinician experience and patient tobacco use20. Although it might be argued that root development of third molars might have associations with postoperative complications in our sample, the age distribution in this study might suggest it to be minimal. This is because the probability of fully developed third molar roots at the age of 18 years is 82–97% according to location36 whereas the study’s participants were 18 years of age or over. Our findings might suggest the need for further exploration of this area in a randomised controlled trial before making a clinical recommendation, because evidence from smaller studies suggests that patient’s age does not contribute significantly to surgical difficulty in third molar removal35.

A limitation of our study was possible recall bias associated with the extraction event and the reported number of third molar extractions received over the past 12 months37. Although our sample is a subgroup analysis of a representative sample of Australian residents, the unweighted count of those who had received third molar extraction was small. Another limitation might be related to the use of the number of days absent from work/school because of dental problems as a proxy for pre-extraction problems and/or recovery period and the unavailability of data on life-threatening infection. On the other hand, our study has several strengths. It contributes to the field of health-care quality by revealing the increased number of third molar extractions associated with dental insurance with no benefit on self-rated oral health in the short-term. This is a potential moral hazard that needs to be thoroughly investigated and supported by clinical data. Our study adds to third molar extraction decision-making by identifying the lack of association between multiple versus single third molar extractions and self-rated oral health in the short term.

In conclusion, being dentally insured versus non-insured was significantly associated with a higher number of third molar extractions reported by Australian adults 18 years of age or over. Receipt of single versus multiple third molar extractions was not significantly associated with self-rated oral health in the short term. This might question the benefit of receiving multiple third molar extractions in the short term, which results in a significant increase in the number of days absent from work/school. Based on these findings, it is recommended to investigate whether the dentally insured participants might be over-managed in the dental setting supported by clinical data to avoid exposing them to unnecessary risks. Over-management associated with private insurance is discussed for health-care services in general and at the service-level for dental procedures. In addition, there might be a need to improve preconsultation patient understanding of the uncertainty related to prophylactic third molar extraction and investigate how this might affect third molar decision-making and decision-outcomes because previous studies suggest that third molar patients are not adequately informed. Although it is widely believed that performing third molar extraction at the age of 18–25 years reduces risks of developing dentally related problems and/or postoperative recovery when compared with an older age group, we observed no significant association with the number of days absent from work/school as a result of dental problems. This might question the use of age as a justification for prophylactic third molar extraction. The need for further studies that address age optimisation for third molar extraction is recommended.

Acknowledgements

This research was part of the principal author’s PhD project for which an Adelaide Scholarship International was received. The research received support from The Australian Research Centre for Population Oral Health (ARCPOH), The University of Adelaide. The authors of this study acknowledge the support provided by the Australian Government Department of Health (AGDoH) and the Australian Institute of Health and Welfare (AIHW) to the NDTIS.

Conflict of interests

The Authors declare that there is no conflict of interest.

References

  • 1.Anjrini A, Kruger E, Tennant M. Cost effectiveness modelling of a ‘watchful monitoring strategy’ for impacted third molars vs prophylactic removal under GA: an Australian perspective. Br Dent J. 2015;219:19–23. doi: 10.1038/sj.bdj.2015.529. [DOI] [PubMed] [Google Scholar]
  • 2.Chrisopoulos S, Harford J. Australian Institute of Health and Welfare; Canberra: 2013. Oral Health and Dental Care in Australia: Key Facts and Figures 2012. Contract No.: Cat. no. Dent 224. [Google Scholar]
  • 3.Singh K, Brennan D, Spencer J, et al. Australian Institute of Health and Welfare; Canberra, ACT, Australia: 2004. Practice Patterns of Oral and Maxillofacial Surgeons in Australia. Contract No.: cat. no. POH 3. [DOI] [PubMed] [Google Scholar]
  • 4.Private Health Insurance Administration Council. Private Health Insurance Australia: Quarterly Statistics; 2013.
  • 5.Australian Private Health Insurance Ombudsman. Dental and oral surgery: Australian Government; 2012. Available from: http://www.phio.org.au/downloads/file/factsandadvise/factsheet-dentaloralsurgery.pdf. Accessed 01 November 2012.
  • 6.Hames K. Question on Notice No. 460 asked in the Legislative Assembly on 11 October 2005 by Dr K.D. Hames; 2005. Available from: http://www.parliament.wa.gov.au/parliament/pquest.nsf/e38eea3a0c4bca1b4825718e00182568/d8d2af5b3eaaff33482571cd002e2dc6?OpenDocument. Accessed 11 October 2005.
  • 7.The Australian Dental Association . Australian Dental Association; Australia: 2015. Wisdom Teeth: To Remove or not to Remove? Available from: http://www.ada.org.au/News-Media/News-and-Release/Latest-News/Wisdom-teeth-To-remove-or-not-to-remove. Accessed 08 May 2016. [Google Scholar]
  • 8.Levinson W, Hudak P, Tricco A. A systematic review of surgeon-patient communication: strengths and opportunities for improvement. Patient Educ Couns. 2013;93:3–17. doi: 10.1016/j.pec.2013.03.023. [DOI] [PubMed] [Google Scholar]
  • 9.Ferrús-Torres E, Valmaseda-Castellón E, Berini-Aytés L, et al. Informed consent in oral surgery: the value of written information. J Oral Maxillofac Surg. 2011;69:54–58. doi: 10.1016/j.joms.2010.05.036. [DOI] [PubMed] [Google Scholar]
  • 10.Cunha-Cruz J, Rothen M, Spiekerman C, et al. Recommendations for third molar removal: a practice-based cohort study. Am J Public Health. 2014;104:735–743. doi: 10.2105/AJPH.2013.301652. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11.Alvin W. Riverina Smiles; Australia: 2016. Use it or Lose it – The End of the Year and your Dental Benefits. Available from: http://www.riverinasmiles.com.au/use-it-or-lose-it-the-end-of-the-year-and-your-dental-benefits/. Accessed 28 April 2016. [Google Scholar]
  • 12.Dodson T, Susarla S. Impacted wisdom teeth. BMJ Clin Evid (Online) 2010;2010:1302. [PMC free article] [PubMed] [Google Scholar]
  • 13.Friedman J. The prophylactic extraction of third molars: a public health hazard. Am J Public Health. 2007;97:1554–1559. doi: 10.2105/AJPH.2006.100271. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Mettes T, Ghaeminia H, Nienhuijs M, et al. Surgical removal versus retention for the management of asymptomatic impacted wisdom teeth. Cochrane Database Syst Rev. 2012;6(6):CD003879. doi: 10.1002/14651858.CD003879.pub3. [DOI] [PubMed] [Google Scholar]
  • 15.McArdle L, Renton T. The effects of NICE guidelines on the management of third molar teeth. Br Dent J. 2012;213:E8. doi: 10.1038/sj.bdj.2012.780. [DOI] [PubMed] [Google Scholar]
  • 16.Salleh A. Wisdom teeth: are we removing them more often than needed? ABCnetau; 2015.
  • 17.Pinho P. The Intangible Benefits of Wisdom Teeth Removal Australia: The Wisdom Teeth Professionals; 2016. Available from: http://www.wisdomdentalemergency.com.au/blog/blogsection/wisdom-teeth-removal/the-intangible-benefits-of-wisdom-teeth-removal. Accessed 28 July 2016.
  • 18.Osunde O, Saheeb B, Bassey G. Indications and risk factors for complications of lower third molar surgery in a nigerian teaching hospital. Ann Med Health Sci Res. 2014;4:938–942. doi: 10.4103/2141-9248.144919. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Bienstock D, Dodson T, Perrott D, et al. Prognostic factors affecting the duration of disability after third molar removal. J Oral Maxillofac Surg. 2011;69:1272–1277. doi: 10.1016/j.joms.2010.06.211. [DOI] [PubMed] [Google Scholar]
  • 20.Santosh P. Impacted mandibular third molars: review of literature and a proposal of a combined clinical and radiological classification. Ann Med Health Sci Res. 2015;5:229–234. doi: 10.4103/2141-9248.160177. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.Tolstunov L. Third molar uncertainty. J Oral Maxillofac Surg. 2013;71:239. doi: 10.1016/j.joms.2012.11.005. [DOI] [PubMed] [Google Scholar]
  • 22.Chrisopoulos S, Harford J, Ellershaw A. Australian Institute of Health and Wellbeing; Canberra, ACT, Australia: 2016. Oral Health and Dental Care in Australia: Key Facts and Figures 2015. Contract No.: DEN 29. [Google Scholar]
  • 23.IBM Corp . 22nd ed. IBM Corp.; New York, NY, USA: 2013. IBM SPSS Coplex Samples. [Google Scholar]
  • 24.IBM Corp . 23rd ed. IBM Corp.; New York, NY, USA: 2015. IBM SPSS Statistics for Windows. [Google Scholar]
  • 25.Brennan D, Ellershaw A. Institute of Health and Welfare; Canberra, ACT, Australia: 2012. Insurance and Use of Dental Services: National Dental Telephone Interview Survey 2010§. Contract No.: Cat. no. DEN 219. [Google Scholar]
  • 26.Hull P, Worthington H, Clerehugh V, et al. The reasons for tooth extractions in adults and their validation. J Dent. 1997;25:233–237. doi: 10.1016/s0300-5712(96)00029-2. [DOI] [PubMed] [Google Scholar]
  • 27.Brennan D, Spencer A. The role of dentist, practice and patient factors in the provision of dental services. Community Dent Oral Epidemiol. 2005;33:181–195. doi: 10.1111/j.1600-0528.2005.00207.x. [DOI] [PubMed] [Google Scholar]
  • 28.George R, Kruger E, Tennant M. The geographic and socioeconomic distribution of in-hospital treatment of impacted teeth in Western Australia: a 6-year retrospective analysis. Oral Health Prev Dent. 2011;9:131–136. [PubMed] [Google Scholar]
  • 29.Srivastava P, Chen C, Harris A. Monash University; Clayton: 2014. Oral Health, Dental Insurance and the Demand for Dental Care in Australia. [Google Scholar]
  • 30.Petrosyan V, Ameerally P. Changes in demographics of patients undergoing third molar surgery in a hospital setting between 1994 and 2012 and the influence of the National Institute for Health and Care Excellence guidelines. J Oral Maxillofac Surg. 2014;72:254–258. doi: 10.1016/j.joms.2013.09.029. [DOI] [PubMed] [Google Scholar]
  • 31.Steed MB. The indications for third-molar extractions. J Am Dent Assoc. 2014;145:570–573. doi: 10.14219/jada.2014.18. [DOI] [PubMed] [Google Scholar]
  • 32.Emanuel E, Fuchs V. The perfect storm of overutilization. JAMA. 2008;299:2789–2791. doi: 10.1001/jama.299.23.2789. [DOI] [PubMed] [Google Scholar]
  • 33.Ku L. Medical and dental care utilization and expenditures under Medicaid and private health insurance. Med Care Res Rev. 2009;66:456–471. doi: 10.1177/1077558709334896. [DOI] [PubMed] [Google Scholar]
  • 34.Hanna K, Brennan D, Sambrook P et al. The impact of guiding patients suffering from wisdom tooth problems through dental open educational resources (DOER) on enhancing shared clinical decision-making and improving health care outcomes: a randomized controlled trial. Australian and New Zealand Clinical Trial Register; 2014. Available from: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366415. Accessed 04 June 2014.
  • 35.Susarla S, Dodson T. Risk factors for third molar extraction difficulty. J Oral Maxillofac Surg. 2004;62:1363–1371. doi: 10.1016/j.joms.2004.05.214. [DOI] [PubMed] [Google Scholar]
  • 36.Gunst K, Mesotten K, Carbonez A, et al. Third molar root development in relation to chronological age: a large sample sized retrospective study. Forensic Sci Int. 2003;136:52–57. doi: 10.1016/s0379-0738(03)00263-9. [DOI] [PubMed] [Google Scholar]
  • 37.Hassan E. Recall bias can be a threat to retrospective and prospective research designs. Internet J Epidemiol [Internet] 2005;3:e1–7. Available from: http://ispub.com/IJE/3/2/13060. [Google Scholar]

Articles from International Dental Journal are provided here courtesy of Elsevier

RESOURCES