• Open Access

The capacity of dental therapists to provide direct restorative care to adults

Authors


Correspondence to:
Hanny Calache, Director Clinical Leadership, Education and Research, Dental Health Services Victoria, GPO Box 1273L, Melbourne, Victoria 3001. Fax: (03) 9341 1234; e-mail: calacheh@dhsv.org.au

Abstract

Introduction: In Victoria, dental therapists are restricted to treating patients under the age of 26 years. Removing this age restriction from dental therapists’ scope of practice may assist significantly in addressing workforce shortages, particularly in rural Victoria.

Objectives: This study aims to assess the capacity of dental therapists to provide direct coronal restorations (dental fillings) to patients older than 25 years, on the prescription of a dentist. Its objectives include determining the success rate of restorations placed by dental therapists six months post placement; and patients’ and dental therapists’ satisfaction with the services provided.

Methods: The project was carried out in 2007 at the Royal Dental Hospital of Melbourne. Seven dental therapists participated in the study, placed 356 restorations (115 patients) with the support of a dentist. These restorations were reviewed six-months post placement by dentists blinded as to which restorations were placed by the dental therapists. Patients’ age ranged from 26 to 82 years (82% were >40 years).

Results: At six months post-treatment, 258 restorations (80 patients) were reviewed. At review, 94.6% of the restorations were successful. Patients and dental therapists were satisfied with the experience.

Conclusions: The standard of restorations provided by dental therapists was considered to be at least similar to that expected of a newly graduated dentist.

Implications: Broadening the dental therapists scope of practice would create opportunities to design more flexible ‘oral health’ clinical teams enabling dentists to provide more complex procedures for patients most in need. This is significant in the public sector and rural areas where workforce shortages are most acute.

In Australia, publicly funded dental services rely on dentists to provide the majority of dental care to adult patients, and compete for graduates in a market skewed toward the private sector. Trends affecting the supply and availability of dental professionals in both the public and private sector in Australia have been well-documented.1 In 2003, it was estimated that by 2010 there will be 1,500 fewer oral health providers than needed just to maintain current levels of access to public dental services.2 However, since then, a number of dental schools have been established across Australia to address this increasing workforce shortage. These include Griffith and James Cook Universities in Queensland; La Trobe University in Victoria and Charles Sturt University in New South Wales. Furthermore, existing schools have increased their dental and oral health therapy student intake numbers to address this issue.

Despite this, demand for public dental services will continue to rise. For example, estimates of growth in numbers of older persons in Australia indicate that while in 2005, people older than 55 years comprised 24% of the total population, by 2020 this group will increase to 31%. In the same period, the number of edentulous (having no natural teeth) persons aged over 55 will decline from 19.5% to 11.0%, implying that there will be increases in demand for dental services for older patients who are retaining their teeth longer.3

The use of dental therapists in Victorian public health services dates from the 1970s, when a shortage of dentists affecting the School Dental Service led to the recruitment and training of school dental therapists. In those years, a two-year Certificate course (later accredited as a Diploma of Applied Science in Dental Therapy) was designed to educate dental therapists to provide basic dental treatment for children using preventive, educational and restorative measures under the supervision, direction and control of dentists. Until 1999, dental therapists could work in the public sector only.

In 1999, the new Dental Practice Act enabled dental therapists in Victoria to work in both the public and private sectors.4 More recently, in 2002, a new Code of Practice for dental therapists and dental hygienists allowed for role expansion with dental therapists providing dental services to children, adolescents and young adults up to the age of 25 years.

In the same year, the Oral Health Therapy curriculum at The University of Melbourne was further developed into the three-year Bachelor of Oral Health program that began in February 2005. Oral health therapy education is expanding in Victoria with another three-year Bachelor of Oral Health Science course established in 2006 at La Trobe University (Bendigo) educating oral health therapists with the skills of both dental therapists and dental hygienists.

In 2004, the National Advisory Council for Oral Health (a subcommittee of the Australian Health Ministers conference [AHMC]) identified the potential to make more effective use of, in the words of the AHMC, ‘dental auxiliaries’, calling for the use of dental therapists, as members of the oral health team, to assist in addressing workforce and clinical demand issues.5 Recently, the Dental Practice Board of Victoria (DPBV) encouraged research aimed at expanding the role of dental therapist and dental hygienists.6

In response to this call from the DPBV, a study was designed to test the hypothesis that, after six months, there will be no difference in the success rate of direct coronal restorations (dental fillings that are placed on the crown of a tooth using a direct technique where the crown of the tooth is prepared by the clinician to receive a permanent filling immediately after cavity preparation) placed by dental therapists on adults older than 25 years and rates reported in the literature for each of the different restorative materials. This success rate is about 90%, according to a review conducted by Sheldon and Treasure.7 If successful, the results of this study would offer the necessary evidence regarding capacity of dental therapists to provide direct coronal restorations to adults older than 25 years of age, under the prescription of a dentist.

This project's objectives were to: i) report on the success rate of restorations (direct coronal restorations) placed by dental therapists six months post-placement; ii) to assess adult patients’ satisfaction with the restorations provided by the dental therapists; and iii) to assess dental therapists satisfaction with the provision of restorations to adult patients older than 25 years of age.

Methods

Preparation stage

During the preparation phase of the project an assessment of the educational needs of the therapist was undertaken. This assessment, in combination with the project's Clinical Advisory Panel recommendations, served in the design and delivery of an orientation and educational program to dental therapists to provide dental care to patients older than 25 years of age. As a result, a three-day educational program was developed. This program included:

  • • an overview of the Dental Health Services Victoria (DHSV) clinic context and systems;
  • • infection control measures in the DHSV clinic;
  • • demographics of adult patients attending the DHSV clinic.
  • • information about medical problems affecting adult patients’ care;
  • • psychological issues in care;
  • • communication skills;
  • • professional and technical skills for the ageing dentition;
  • • the impact of partial dentures on the dentition, on dental restorations, and on occlusion;
  • • a review of dental materials;
  • • periodontology (the study of the disease and conditions of the structures that support the teeth); and
  • • health promotion approaches for adult patients.

During this stage, approvals were obtained from the Dental Health Services Victoria's Human Research and Ethics Committee, and from the University of Melbourne's Health Sciences Human Ethics Sub-Committee. Additionally, temporary licensing, for dental therapists selected for the project to provide direct coronal restorations to eligible patients older than 25 years of age, under the prescription of a dentist, was arranged with the Dental Practice Board of Victoria.

A standardised assessment tool was developed for the study. This tool was based on criteria originally developed by Ryge and reviewed by several authors.8–11 This form was used by all dentists and dental therapists involved in the study. Based on Ryge's reviewed criteria, each restoration was scored on Surface and colour, Anatomic form and Marginal integrity into five assessment levels. These levels are shown in Table 1. Where a restoration was scored by either the dental therapist, dentist or both as not meeting all standards (Levels 2–5), additional clinical notes were made.

Table 1.  Restoration assessment criteria.
Assessment LevelOperational categoryOperational explanation
1Meets all standardsThe restoration is of an excellent quality and is expected to adequately protect the tooth and the surrounding tissue.
2AcceptableThe restoration is of acceptable quality, but exhibits one or more features which may be corrected by polishing.
3SatisfactoryThe restoration is of satisfactory quality. Restoration has minor shortcomings which cannot be eliminated without damage to the tooth.
4Needs to be corrected or repairedThe restoration has defects which need to be corrected or repaired.
5Must be replaced immediatelyThe restoration is missing or fractured and must be replaced immediately.

Recruitment stage

Recruitment of dental therapists

Recruitment of dental therapists for this project was conducted in December 2006. Selection criteria for dental therapists included the following: extensive experience, high motivation, keenness to work with adult patients, possessing a current radiation licence, registration with the Dental Practice Board of Victoria and strong referee reports.

Two full-time dental therapists and five part-time dental therapists were recruited for the study from a pool of 11 applicants. These seven dental therapists equated to four Full-time Equivalent dental therapists.

Recruitment of patients

In December 2006, recruitment of patients commenced. Potential patients were identified from the waiting lists for 4th and 5th year dental students by selecting patients older than 25 years, who met criteria outlined below. A letter was sent to all potential patients (n=452), advising them about the dental therapists project and inviting them to volunteer to participate in the study. In the letter, patients were advised that, if selected for the study, they would receive free restorative treatment (i.e. no fee or co-payment) and with minimal waiting time. To facilitate response, a reply paid envelope was enclosed.

To all those who replied, an appointment was organised with an assessing dentist. Three assessing dentists were recruited to work in the project. They conducted the initial screening of patients for suitability to be treated by the dental therapists and prescribed treatment plans for the patients.

Patient selection criteria

To be eligible for the study the patients needed to be older than 25 years of age, and hold a current Health Care Card (concession card). A patient would be excluded from the project if he/she:

  • • had full upper and lower dentures,
  • • had an occlusal imbalance,
  • • were homebound or in nursing home accommodation,
  • • had unstable medical condition(s) e.g. poorly controlled diabetes or epilepsy,
  • • had a bleeding disorder,
  • • had intellectual, physical, or sensory disabilities, or
  • • had no capacity to give consent.

In addition, a tooth would be excluded from the study if it:

  • • had a cavity on a root surface (carious or non-carious),
  • • had a cavity or cavities adjacent to extra-coronal restorations on the same tooth,
  • • had exposed dentine due to attrition or erosion,
  • • required complex restorative techniques, defined as restorations requiring cusp replacement or additional retention (e.g. pins),
  • • were affected by advanced periodontal disease (periodontitis),
  • • required indirect restorations, defined as restorations formed outside of the mouth on models of prepared teeth, or
  • • required root surface restorations.

The clinical phase

The clinical phase commenced on January 2007 and extended over a six-week period.

Dental therapists were located at the Royal Dental Hospital of Melbourne (RDHM), in a group setting with a supporting dentist on site at all times. The supporting dentists were recruited from a pool of dentists familiar with the RDHM clinic and were highly experienced in clinical teaching and supervision of dental students at the School of Dental Science at the University of Melbourne. The supporting dentists were required to undertake an examination of the patient and the prescription referred to the therapists by the assessing dentist and to confirm that the procedure and the patient were suitable for management by the dental therapist. The supporting dentists were also required to provide “support to the therapist as required”, rather than “direct supervision” at every stage of the restorative procedures undertaken by the dental therapist, on issues related to choice of dental materials and appropriate technique, or if the therapists considered the prescribed treatment to be beyond their scope of practice.

One supporting dentist was allocated to a group of dental therapists (three to four therapists) at any one time. Their location was also close to that of the assessing dentist team, so a patient could be referred across on the same day as the initial assessment. This proximity also enabled discussion about the patients’ needs and proposed care with the dental therapists, and contributed to the simulation of an oral health team environment.

In addition, supporting dentists undertook the assessment of restorations immediately after placement by the dental therapist, using the assessment tool developed as part of the study. Each restoration was assessed at the time of placement by the dental therapist and the supporting dentist.

At the end of each treatment session, the supporting dentist provided feedback on the standard of restorative treatment provided by the therapist and the dental therapists provided feedback on their experience with providing restorative treatment to adult patients.

Patients were also asked to complete a feedback form. This form asked them to rate their satisfaction of their experience with the dental therapist, in terms of:

  • • the explanation and information received;
  • • the dental treatment received from the dental therapist;
  • • the helpfulness of the dental therapist; and
  • • the professional skills of the dental therapist.

Review phase

Once inserted, restorations may fail at variable rates due to a number of factors.7 For this reason, a review phase was organised six months post-treatment and extended from July to August 2007. Review at six months was considered appropriate as the failure rate of most dental material [Amalgam, Resin Composites, Glass Ionomer Cement (GIC)] at six months after being placed has been reported to be less than 10%.7 In addition, evidence indicates that failure of restorations within six months of placement is more likely to be attributed to operator skills, whereas failure of restorations beyond six months is more likely to be due to dental materials’ properties or other external factors such as heavy or unbalanced occlusion, bruxing or grinding of teeth.7,12

At the review sessions, the restorations placed by the dental therapists were reviewed by trained and calibrated dentists who were blinded as to which restorations had been placed by the dental therapists. The reviewing dentists, a different group from the supporting dentists, were requested to chart and assess all restorations present in the oral cavity of each patient. The reviewing dentists were also recruited from a pool of dentists highly experienced in clinical teaching and supervision of final year dental students.

Sample size

The unit of study was the restoration. A restoration could be of three types: Amalgam, Resin Composite or GIC. The sample size (number of restorations) required to test the null hypothesis of a success rate of 90%, at the 0.05 level of significance, for 80% power of detecting a difference in proportion of success of five percentage points or greater, would be 316 restorations.13

Analysis

The analysis provides basic descriptive information on the distribution of restorations placed by the dental therapists and their outcome according to Ryge's reviewed criteria. In addition to the descriptive data, this analysis provides insight into the patients’ satisfaction with the restorative services received; as well as dental therapists’ satisfaction with the provision of restorative services.

Results

Of the 452 letters that were mailed out, acceptance to participate totalled 195, a response rate of 43.4% from all contacts. Of these, a total of 115 patients were selected by the assessing dentist to be treated by the dental therapists, 48 (41.7%) male and 67 (58.2%) female. The youngest patient treated by dental therapists was 26 years and the oldest 82 years, the mean age being 53.7 years (80% were older than 40 years of age). Comparison of the characteristics of these patients with those of patients attending for general care confirmed that this was a representative sample of the RDHM patients’ population, in terms of age and gender.

In total, the dental therapists placed 356 restorations as prescribed by the assessing dentists. One hundred and twelve restorations were placed in anterior teeth (i.e. incisors and canines), and 244 restorations were placed in posterior teeth (i.e. molars and premolars). The majority of restorations placed on posterior teeth were Resin Composite Resin restorations (46.3 %), whereas amalgam was used mostly for multisurface restorations (i.e. 2 or more surfaces) (See Table 2).

Table 2.  Number of restorations placed by dental therapists.
Type of teeth restoredMaterial1 surface (%)2 surfaces (%)3 or more (%)Total
Anterior TeethResin Composite and Glass Ionomer Cement54 (48.2)32 (28.5)26 (23.3)112
Posterior TeethAmalgam19 (23.2)42 (51.2)21 (25.6)82
 Resin Composite60 (53.1)41 (36.3)12 (10.6)113
 Glass Ionomer Cement38 (77.5)8 (16.3)3 (6.2)49
Total 17112362356

At time of placement, most restorations (n=335; 94.1%) were assessed as meeting all standards (Level 1) and 21 (5.9%) were assessed as acceptable (Level 2). At that time, no restorations were assessed as either satisfactory (Level 3) or as in need of correction, repair of replacement (Levels 4 and 5), see Table 3.

Table 3.  Scores for restorations placed by dental therapists at time of placement and at six months review.
Assessment TimeAssessment category (Level)Number of Restoration (%)
At time of placementMeets all standards (1)335 (94.1)
 Acceptable (2)21 (5.9)
 Satisfactory (3)0
 Needs correction, repair or replacement (4 or 5)0
 Number of restorations placed356 (100)
At six months reviewMeets all standards (1)125 (48.5)
 Acceptable (2)105 (40.7)
 Satisfactory (3)14 (5.4)
 Needs correction, repair or replacement (4 or 5)14 (5.4)
 Number of restorations reviewed258 (100)

The review examinations were held from July to August 2007. Eighty (69.5%) patients and 258 (72.5%) restorations were reviewed. Numerous efforts made to recall all 115 patients revealed that of the 35 patients who could not be reviewed, many had changed address, 18 not being contactable, three had taken up work and were unable to take time off to attend, eight were away from home or otherwise unavailable, four made an appointment but failed to attend and two rang in sick. The mean age of the 35 non-attenders was 48.9 years, range 26–74 years, and the gender break down comprised 65.7% females and 34.3% males. Thirty-two had suburban and three had rural or distant postcodes. There were no discernable patterns of difference between those patients who attended for review, and the non-attenders. Of the 258 dental therapist-placed restorations that were reviewed, 244 (94.6%) of restorations were confirmed as either Meeting all standards, or Acceptable, or Satisfactory. Ten patients had a total of 14 restorations (5.4%), which required restorative care, whether it was correction, repair or replacement (Levels 4 or 5) (See Table 3). The nature of the defects noted in the restorations placed by the dental therapists were no different to what would be expected if a dentist had placed the restorations.

One of these 10 patients had three out of five restorations that needed repair or replacement. Another two patients had two restorations each needing repair or replacement, while seven patients had one restoration each, which required re-treatment. As the dental therapists worked different hours, this meant that patients were treated by more than one dental therapist. Hence there was no particular operator effect related to restorations needing re-treatment. Table 4 shows that the lowest proportion of restorations in posterior teeth requiring correction repair or replacement was for amalgam restorations, whereas the highest proportion was GIC restorations.

Table 4.  Assessment scores at six months review by dental materials used.
Type of Teeth RestoredMaterialNumber of RestorationsLevel 1–3 (meets all standards/ acceptable/ satisfactory) (%)Level 4–5 (needs correction, repair or replacement) (%)
Anterior TeethResin Composite/GIC8481 (96.4)3 (3.6)
Posterior TeethAmalgam5654 (96.4)2 (3.6)
 Resin Composite7874 (94.8)4 (5.2)
 Glass Ionomer Cement4035 (87.5)5 (12.5)
Total 258244 (94.6)14 (5.4)

Due to multiple restorations and multiple visits by a number of patients a total of 145 feedback forms were collected at the time of placement of restorations from 115 patients for the 356 restorations placed. At least one feedback form was collected from each patient. All patients at the time of placement of the restorations expressed strong satisfaction with the dental therapists’ work. Comments received corroborated the patients’ acceptance of dental therapists providing care. All patients expressed strong satisfaction with the explanations, information and dental treatment received, the general helpfulness of the dental therapists, the therapists’ professional skills, and the review provided by the dentist.

At the time of the six-month review, out of 80 patients reviewed, 72 (90%) said that they would return for dental therapist treatment, and 70 (87.5%) stated that they would recommend dental therapist treatment to other adults. Two patients (2.5%) commented that they would prefer to be treated by a dentist for management of their gums or if the filling is a big job.

The two principal supporting dentists prepared a report at the end of the clinical phase on their experience of working with the dental therapists. Overall, this assessment indicated that the standard of restorations provided by the dental therapists to adults older than 25 years was at a similar standard to that expected of newly graduated dentists. Examples of supporting dentists’ comments include:

Patient management at all age groups was excellent with good interaction between patients and dental therapists.

Local anaesthetic selection and procedural technique were appropriate and effective.

Handpiece control and technique were excellent.

When dental therapists were asked to report their level satisfaction with the provision of restorative service to patients older than 25 years, they all considered the experience as extremely rewarding and appreciated the gains they made in knowledge and technical skills. Dental therapists enjoyed their work with adult patients, in particular:

  • • the opportunity to discuss needs with the patient, in an adult-to-adult way that is not possible with child patients;
  • • the cosmetic results of some of their work on anterior teeth, where patients’ appearance was considerably improved; and
  • • the social interaction and appreciation shown by patients.

Discussion

This study was designed to assess the capacity of dental therapists to provide direct coronal restorations to adults older than 25 years. The results of this study indicate that, after six months of placement, 94.6% of the direct coronal restorations placed by dental therapists were assessed as meeting all standards, acceptable or satisfactory. The remaining 5.4% required re-treatment.

This failure rate is in line with that reported in the literature for most dental material at six month of being placed, which has been reported to be less than 10%.6 In this study, GIC in posterior teeth had the greatest failure rate (12.5%). However, Sheldon & Treasure,6 also highlighted that this type of restorative material may have a higher replacement rate.

The supporting dentists’ report confirmed that this group of dental therapists’ level of professionalism and ability to provide safe treatment to adults 26 years or older was at a standard, at least, similar to that expected of newly graduated dentists.

Furthermore, the satisfaction of patients participating in the study reflects a high level of acceptance of the work of the dental therapists. In the same manner, the therapists also expressed a high level of satisfaction with their experience of working with adult patients.

These outcomes support our hypothesis that dental therapists can provide effective direct coronal restorations to selected adult patients under the prescription of a dentist and in a service model as evaluated in this project.

For the purposes of this study, it was considered that the dental therapists’ direct coronal restorative skills in the permanent dentition were highly developed as a product of years of experience with child, adolescent and young adult patients, so the main issue in this project was not the assessment of new learning and competencies, but the transferability of existing skills to consenting adult patients older than 25 years. Nonetheless, based on the educational program provided as part of this study and the feedback from the supporting dentists and the dental therapists who participated in the study, it is proposed that a dental therapist would require approximately 70 hours of additional training [didactic (28 hours), clinical observation (14 hours) and clinical practice (28 hours)] to support their capacity to provide direct coronal restorative services to adults older than 25 years on the prescription of a dentist.

In conclusion, the study provides support for the extension of the dental therapists’ Code of Practice to allow dental therapists to provide direct coronal restorations to adults older than 25 years of age, on completion of an approved course of education including experience in an adult clinical setting. Broadening the dental therapists Code of Practice in this way will create opportunities to design more flexible oral health clinical teams as dental therapists may provide some of the routine direct coronal restorative services to adults. This will free up dentists for more complex procedures for those patients who are most in need. This would be of particular value in the public sector and in rural areas where workforce shortages are most acute. The economic viability of this model is an area requiring further research.

Acknowledgements

The authors would like to acknowledge the support received from the Dental Health Services Victoria (DHSV) and the participants in this study. In particular, we would like to acknowledge the staff of the project and the dental examiners.

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