Accuracy and reliability of 2-dimensional photography versus 3-dimensional soft tissue imaging

PURPOSE: This study was conducted to objectively and subjectively compare the accuracy and reliability of 2-dimensional (2D) photography and 3-dimensional (3D) soft tissue imaging.MATERIALS AND METHODS: Facial images of 50 volunteers (25 males, 25 females) were captured with a Nikon D800 2D camera (Nikon Corporation, Tokyo, Japan), 3D stereophotogrammetry (SPG), and laser scanning (LS). All subjects were imaged in a relaxed, closed-mouth position with a normal smile. The 2D images were then exported to Mirror® Software (Canfield Scientific, Inc, NJ, USA) and the 3D images into Proplan CMF® software (version 2.1, Materialise HQ, Leuven, Belgium) for further evaluation. For an objective evaluation, 2 observers identified soft tissue landmarks and performed linear measurements on subjects' faces (direct measurements) and both linear and angular measurements on all images (indirect measurements). For a qualitative analysis, 10 dental observers and an expert in facial imaging (subjective gold standard) completed a questionnaire regarding facial characteristics. The reliability of the quantitative data was evaluated using intraclass correlation coefficients, whereas the Fleiss kappa was calculated for qualitative data.RESULTS: Linear and angular measurements carried out on 2D and 3D images showed excellent inter-observer and intra-observer reliability. The 2D photographs displayed the highest combined total error for linear measurements. SPG performed better than LS, with borderline significance (P=0.052). The qualitative assessment showed no significant differences among the 2D and 3D imaging modalities.CONCLUSION: SPG was found to a reliable and accurate tool for the morphological evaluation of soft tissue in comparison to 2D imaging and laser scanning.

Judging orthodontic treatment complexity

Objective: The aim of the present study was to investigate possible relations between anticipated overall treatment complexity (AOTC) of an orthodontic case and malocclusion characteristics. Methods: Two groups of orthodontists (groups A and B) were asked to define perceived treatment complexity (PTC) of orthodontic cases based on 16 characteristics of malocclusion by means of a questionnaire. Each question was answered on a six-point ordinal scale, with one "not applicable" option (score 0). Group A was also asked to give the AOTC of the specific case on a five-point ordinal scale. The index of orthodontic treatment need (IOTN) score of the specific cases as well as the malocclusion characteristics were assessed by one author. Results: There is a significant relationship between IOTN and AOTC (p< 0.0001), 22% of variability is explained by differences in IOTN. Adding objective characteristics of malocclusion to explain AOTC does not significantly increase the explained variability (p = 0.086). In judging interobserver agreement, a weighted Kappa of 0.60 for group A and 0.56 for group B was found. The weighted Kappa for agreement in AOTC equals 0.06. Conclusion: The relation between IOTN and AOTC was found to be significant. Moderate agreement on PTC among observers and a low level agreement regarding AOTC were found in the present study.

Objetivo: o objetivo do presente estudo foi investigar possíveis relações entre a previsão da complexidade geral do tratamento (AOTC, Anticipated Overall Treatment Complexity) de um caso ortodôntico e as características da má oclusão. Métodos: dois grupos de ortodontistas (Grupo A e Grupo B) foram orientados a definir, por meio de um questionário, sua percepção da complexidade do tratamento (PTC, Perceived Treatment Complexity) de casos ortodônticos, com base em 16 características da má oclusão. Cada questão foi respondida em uma escala ordinal de seis pontos, com a opção "não aplicável" (nota 0) disponível. Pediu-se ao Grupo A que também determinasse, em uma escala ordinal de cinco pontos, a AOTC de cada caso. A nota relativa ao índice de necessidade de tratamento ortodôntico (IOTN,Index of Orthodontic Treatment Need) de casos específicos e as características das más oclusões foram avaliadas por um dos autores. Resultados: existe uma relação significativa (p < 0,0001) entre o IOTN e a AOTC. Diferenças no IOTN são a causa de 22% da variabilidade. Adicionar características objetivas da má oclusão para explicar a AOTC não aumentou significativamente essa variabilidade mencionada (p = 0,086). Ao se avaliar a concordância interexaminadores, foram encontrados valores de Kappa ponderado de 0,60 para o Grupo A e 0,56 para o Grupo B. O valor de Kappa ponderado para a concordância quanto à AOTC foi de 0,06. Conclusão: a relação encontrada entre o IOTN e a AOTC foi considerada significativa. Verificou-se uma moderada concordância interexaminadores com relação à PTC, e um baixo nível de concordância com relação à AOTC.