Magister Scientiae Dentium - MSc(Dent) / BACKGROUND: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. AIM: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. METHOD: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). RESULTS: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). CONCLUSION: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models.

>Magister Scientiae - MSc / Background: Plaster models form an integral part of the traditional orthodontic records. They are necessary for diagnosis and treatment planning, case presentations as well as for the evaluation of treatment progress. The accuracy of the measurements taken for space assessment is crucial prior to treatment planning. The introduction of digital models overcomes some problems experienced with plaster models. Digital models have shown to be an acceptable alternative for plaster models. Aim: The aim of the study was to determine the accuracy of traditional measurement techniques when compared to the CAD/ CAM measurements in the assessment of tooth widths and arch perimeter from plaster models. Method: The mesio-distal tooth widths and arch perimeter of thirty archived plaster models were measured using a digital caliper to the nearest 0.01 mm and divider to the nearest 0.1 mm. Corresponding digital models were produced by scanning them with a CAD/CAM (InEos X5) and space analysis completed by measurements using InEos Blue software. Measurements were repeated after 1 week from the initial measurement. The methods were compared using descriptive analysis (mean difference and standard deviation). Results: The operator reliability was high for digital models as well as the plaster models when the measurement tool was the digital caliper (analyzed using the Pearson correlation coefficient in the paired t-test). The mean values of tooth widths measurements of CAD/CAM, digital caliper and divider were 6.82 (±0.04), 6.94 (± 0.04) and 7.11 (± 0.04). There was a significant difference between the measurements made by the CAD/CAM and the divider. Additionally significant differences between the measurements by digital caliper and divider measurements (p < 0.05) were observed. No significant difference was found when comparing CAD/CAM to digital caliper. Positive correlation was displayed between CAD/CAM, digital caliper and the divider, but the measurements completed with the digital caliper had the highest correlation with the CAD/CAM. The difference was not significant between the aforementioned measurement tools (p > 0.05). Arch perimeter measurements showed no statistical significant difference between CAD/CAM, digital caliper and divider (p < 0.05). Conclusion: Archived plaster models stored as records can be converted to digital models as it will have the same accuracy of measurements. The value of doing a space analysis with the CAD/CAM system can be performed with similar reliability on the digital models as a caliper on plaster models.

Introduktion:Modellanalys har traditionellt gjorts på fysiska gipsmodeller. Idag finns ny teknik som möjliggör framställning av digitala modeller utan behov av konventionella avtryck. Syftet med den här studien är att undersöka tillförlitligheten hos digitala modeller framställda med en intraoral scanner, patientupplevelsen och olika tidsaspekter förenade med tekniken.Metod:På ett urval av 20 vuxna personer gjordes både konventionell avtryckstagning och en intraoral scanning (TRIOS, 3Shape) av bettet för framställning av gipsmodeller och digitala modeller. Den kliniska tidsåtgången mättes och personerna besvarade ett frågeformulär gällande sin upplevelse av metoderna. Fyra observatörer diagnostiserade bettrelationer och utförde ortodontiska mätningar på gipsmodeller med ett skjutmått och digitala modeller med OrthoAnalyzer Orthodontics (3Shape, Danmark). Tidsåtgången mättes för digital- respektive konventionell modellanalys. Statistiska analyser gjordes utifrån Paired samples t test, korstabeller och frekvensanalys.Resultat:Diagnostik av horisontella-, vertikala- och transversella bettrelationer på digitala modeller har hög tillförlitlighet. Få statistiskt signifikanta skillnader fanns för linjära mätningar på digitala modeller jämfört med gipsmodeller. För majoriteten av observatörerna tog digital modellanalys längre tid än konventionell modellanalys. Likaså var den kliniska tidsåtgången för intraoral scanning signifikant längre än för konventionell avtryckstagning och metoden prioriterades lägre av försökspersonerna.Konklusion:Digitala modeller framställda med en intraoral scanner är en tillförlitlig metod för ortodontisk diagnostik och terapiplanering. Tekniken har en rad fördelar och förbättras ständigt men dess acceptans för den enskilde klinikern blir i slutändan en kostnadsfråga. / Introduction:Model analysis has traditionally been carried out on physical plaster models. New technology allows the production of digital models without the need for conventional impressions. The purpose of this study was to evaluate the validity of digital models made with an intraoral scanner, patient experience and different time aspects associated with this technology.Methods:A sample of 20 adults was selected. Plaster models and digital models were obtained from conventional impressions and an intraoral scanning (TRIOS, 3Shape) respectively. The clinical time required for impression taking and intraoral scanning was recorded and the subjects were asked to answer a questionnaire regarding their experience of both methods. Four independent examiners diagnosed malocclusions and performed measurements with a digital caliper on plaster models and by using OrthoAnalyzer Orthodontics (3Shape, Denmark) for digital models. Time required for digital- and conventional model analysis respectively, was recorded. Statistical analysis was performed by using Paired samples t test, crosstabs and frequency analysis.Results:Diagnostics of horizontal-, vertical- and transversal malocclusions with digital models showed high validity. Few statistically significant differences were found for measurements made on digital models compared to direct measurements on plaster models. For a majority of the examiners, digital model analysis was more time consuming than conventional model analysis. Also, clinical time required for intraoral scanning was significantly greater than for conventional impression taking. The subjects preferred conventional impression taking.Conclusions:Digital models made with an intraoral scanner are a reliable method for orthodontic diagnostics and treatment planning. The technique has a number of advantages and is constantly improving but its acceptance depends ultimately on the cost-effectiveness ratio to the individual practitioner.