A Comparison of Conventional Versus Digital PAR (Peer Assessment Rating) Scores Using an Intraoral Scanner
Condition: Malocclusion
MeSH terms: Malocclusion
Study type: Observational

Summary: 
      In dentistry, Peer Assessment Rating (PAR) is an objective way of quantifying how maligned a
      patient's teeth are by scoring orthodontic study models. It can also be used to assess
      treatment outcome by comparing pre- and post-treatment scores. Traditionally, PAR scoring is
      performed manually on plaster casts by a trained and calibrated individual. The plaster casts
      consume considerable amounts of storage space and the process of manual scoring can be time
      consuming and expensive. The recent decades have seen a rise in popularity of intra oral
      scanners in dentistry to produce digital study models. These obviate the need for physical
      storage space and a software can be used to calculate PAR scores more conveniently and at a
      faster speed. A review of the current literature showed that the CS 3600 intra oral scanner
      by Carestream Dental demonstrated acceptable accuracy for clinical use.

      In this study, patients will receive the usual impressions and their moulds will be PAR
      scored manually (usual care pathway). In addition, they will also receive intra oral scans
      with Carestream 3600 and the digital models will be scored by a computer. Manual and digital
      scores will be compared and analysed for any significant discrepancies.
    

Detailed description: 
      CS 3600 intra oral scanner is already licenced for the use in dentistry and is routinely used
      by some dental practitioners to substitute conventional impressions and plaster models in
      restorative, implant and orthodontic diagnosis and treatment planning. The scanner is 220 x
      38 x 58 mm in size and operates with video capture technology. It emits no radiation.

      Peer Assessment Rating (PAR) is an objective way of quantifying how severe a malocclusion is
      by scoring orthodontic study models. It can also be used to assess treatment outcome. All
      National Health Service (NHS) orthodontic providers in the United Kingdom are contractually
      bound to submit PAR score changes for at least 20 of their treated cases plus 10% of the
      remainder of their case load every year. Traditionally, PAR scoring is performed manually on
      plaster casts by a trained and calibrated individual. The plaster casts must be retained as
      part of the patient's medical records and hence consume considerable amounts of storage
      space. The process of manual scoring is also time intensive. Digital models obviate the need
      for physical storage space and a software can be used to calculate PAR scores more
      conveniently and at a faster speed. A review of the current literature showed that the CS
      3600 intra oral scanner by Carestream Dental demonstrated acceptable accuracy for clinical
      use. The purpose of this study is to assess the accuracy of PAR scores obtained from digital
      models with those obtained manually from conventional models for the same patient at one
      given point in time.

      Aims: Against this background, the aim of this study is to compare digital PAR scoring using
      the CS 3600 intraoral scanner with conventional PAR scoring.

      Objectives: The objectives are to investigate whether PAR scoring on models acquired through
      direct and indirect digitisation produces any significant errors when compared with
      conventional PAR scoring on plaster models. The study will also seek to measure the chairside
      time taken to produce upper and lower full arch scans and bite registration with CS 3600
      versus the time taken to produce equivalent alginate impressions and wax bite. Furthermore,
      the time taken for digital scoring will be measured and compared with the conventional
      method. Finally, patient preference with regard to intraoral scans versus impressions will be
      investigated.

      Method: The sample size was confirmed using a power calculation. The sample will consist of
      66 orthodontic patients at Kingston Hospital, excluding any patients with fixed appliances or
      bonded components. All patients will receive conventional impressions as well as intraoral
      scans, serving as their own controls. Plaster casts poured from the impressions will also be
      scanned to produce indirect digital models. PAR scoring will then be performed by one
      investigator on all three models (plaster casts, direct and indirect digital models) for
      comparison. A second investigator will record the time taken to perform scans and impressions
      as well as the time taken to complete digital and conventional scoring. Immediately after the
      clinical procedure patients will be given a questionnaire evaluating their preference.

      Data analysis: Data from the PAR scorings and questionnaires will be recorded and analysed
      using SPSS following consultation with a bio-statistician. The data will then be graphically
      represented in the form of tables and charts.
    

Intervention name(s): Carestream 3600 intra oral scan
Intervention type(s): Device
Intervention description(s): Carestream 3600 is CE marked intra oral scanner manufactured by Carestream Dental. It is already licensed for use in dentistry to produce digital study models. The scanner is 220 x 38 x 58 mm large and operates using video capture technology. It emits no radiation.
Carestream 3600 is connected to a computer via a USB port and a computer software (CS Model +) converts the scan into digital study models using trigonometric calculations. The software is then used to take measurements on the digital models and calculate PAR scores
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        orthodontic patients at Kingston Hospital
      
Keywords: PAR scoring; Digital study models