Orthodontic Patient Experience of Intraoral Scans Versus Alginate Impressions

Orthodontic Patient Experience of Intraoral Scanners Versus Alginate Impressions in the UK: a Single-Centre Randomised Controlled Crossover Trial

CONTEXT: Digital scanning systems are becoming more and more popular with the advent of the COVID-19 pandemic. The risks surrounding aerosol-generating procedures (AGP) has resulted in practitioners changing their normal practice and finding alternative methods to continue managing their patients. Digital (intraoral) scanners are often used to show patients treatment options and help in educating them regarding their oral hygiene as it produces an almost instant digital image of their teeth. Conventional methods using alginate impressions produce study models which are created in dental plaster or stone, involving a lab cost and a greater environmental impact but remain a popular method of recording a patient's teeth and bite.

OBJECTIVE: To investigate patient experience, operator experience and preference in intraoral scanning versus alginate impression taking in the orthodontic setting.

DESIGN, SETTING AND SUBJECTS: A randomised controlled two-period crossover trial to be conducted in a UK secondary care setting involving 84 participants ready to start orthodontic treatment, with no experience of impressions/intraoral scans in the last 2 years. Patients with cleft lip and/or palate or recent research involvement will be excluded.

OUTCOMES: A modified visual analogue scale, will be used to measure patient and operator reported outcomes (e.g. patient comfort, operator confidence, perceived time taken and induction of cough/gag reflex) following an alginate impression or an intraoral scan using Trios® 3 intraoral scanner (3Shape). The time taken for each procedure will also be measured. Lastly, operator preference will be recorded.

CONCLUSION: The proposed study aims to add to the limited evidence base, providing information regarding the use of intraoral scanners compared to alginate impressions from both the orthodontic patient and operator perspectives.

Eligible patients are to be identified during a virtual dental health education (DHE) appointment prior to their orthodontic treatment commencing. With consent, the trial will be discussed with patients meeting the inclusion criteria and they will be provided with relevant trial information in both leaflet and video format. The potential participant and/or their parent or guardian will be allowed time (3 weeks) to consider the information and ask any relevant questions. If they choose to take part in the trial, they will be recruited and allocated randomly into mixed block sizes using an online randomisation tool. If they choose not to participate, normal orthodontic care will continue. For children, unable to consent for themselves, assent will also be sought.

Once the participant has provided appropriate consent/assent, the following procedure will be followed:

• One unit will be set up with an operator and a nurse

Participants in the alginate impression group:

1. The unit the participant will be treated in, will be set up appropriately with relevant materials ready.

   • The alginate to be used will be: Zhermack orthoprint® orthodontic alginate material

2. A timer will be started when the participant is seated in the chair

3. The operator will carry out the impression as normal:

   • Tray selection
   • Alginate mixing
   • Tray seating
   • Alginate setting
   • Tray removal
   • Wax bite
   • Clean up of the participant's face

4. The timer will be stopped

5. Questionnaires

   • Participant will be asked to complete a questionnaire (modified VAS using pictorial anchors)
   • Operator will be asked to complete a questionnaire

6. These will be collected for analysis

7. The participant will then have records taken as part of their normal orthodontic care, if not done already +/- a discussion to consent patient for orthodontic treatment

8. The participants will return a minimum 4 weeks later for a second appointment (if they have not had an intraoral scan already) in which they will undertake the process for 'Participants in the intraoral scanner group'

Participants in the intraoral scanner group:

1. The unit the participant will be treated in, will be set up appropriately with relevant materials ready. The interchangeable covering will be placed over the scanner ready for use.

   • The intraoral scanning device to be used will be: Trios® 3 intraoral scanner (3Shape)
   • The staff will be appropriately trained and will be requested to carry out a minimum of 10 scans prior to the study beginning

2. A timer will be started when the participant is seated in the chair

3. The scan will be carried out as per the manufacturer's directions to include a full mouth scan and bite registration and saved on the scanner system.

4. The timer will be stopped

5. Questionnaires

   • Participant will be asked to complete a questionnaire (modified VAS using pictorial anchors)
   • Operator will be asked to complete a questionnaire

6. These will be collected for analysis

7. The participant will then have records taken as part of their normal orthodontic care, if not done already +/- a discussion to consent patient for orthodontic treatment +/- fit of any orthodontic appliance required.

8. The participants will return a minimum 4 weeks later for a second appointment (if they have not had an alginate impression already) in which they will undertake the process for 'Participants in the alginate impression group'

A minimum of 4 weeks between the two appointments allows for an adequate washout period and it also fits with orthodontic laboratory work timelines within the hospital.

Once all participant data is obtained, the operators will be asked a single question to indicate their preference towards a single method.

Any participant and/or their parent or guardian, if appropriate who wishes to withdraw at any point during the trial can do so without reason and without this affecting or prejudicing the delivery of their orthodontic care.

Analyses:

• Primary outcome - the difference between the paired visual analogue scale (VAS) scores will be compared using analysis of variance (ANOVA) that will analyse the period, treatment and sequence effects of the comfort scores.
• Secondary outcomes - the 8 secondary outcomes measured by VAS and the time taken to make the impression or complete the scan will be compared using analyses of variance suitable for a crossover study, that will test the period, treatment and sequence effects on these nine secondary outcomes. The operator's preference will be reported using descriptive statistics. The frequency and percentages will be recorded.

Only the primary analysis will be compared against a specific level of significance. The secondary analyses should be considered as hypothesis generating rather than providing firm conclusions.

Inclusion Criteria:

• New patients, aged 10 years and old, attending the Royal Derby Hospital orthodontic department, requiring study model impressions taken prior to commencing orthodontic treatment
• Participants must be capable of giving informed consent, or have an acceptable individual capable of giving consent on the patient's behalf (e.g. parent or guardian of a child under 16 years of age).

Exclusion Criteria:

• Patients who have had previous experience of impressions/intraoral scans in the last 2 years
• Cleft lip and/or palate patients
• Patient who have been involved in a study in the last 6 months or are currently part of a study