Survival analysis with clustered observations of orthodontic brackets

Elisabetta Petracci, Mauro Farella, Carlotta Galeone, Alessandra Albano, Monica Ferraroni, Adriano Decarli

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Failures in the bonding of dental bracket are a big concern for orthodontists. Clinical experience suggests that some patients are more prone than others to experience failures. Therefore, it can be expected that in statistical analysis of orthodontic bracket failures, the usual assumption of independence between the observations is violated. An approach to overcome this problem is to apply the frailty model, in which the association between failure times is modelled with a random-effect term (i.e. frailty). We postulated that brackets of the same subject share the same frailty, that is, a latent common group effect, due to some unknown or unobserved covariates. The aim of this study was to investigate possible risk factors related to bracket failure using Cox proportional hazards model with a shared frailty term and to compare the results with those obtained using a basic Cox proportional hazards model. Survival data for 1677 brackets were obtained from a cohort of 54 females (mean age ± SD: 13.3±4.8yrs) and 46 males (mean age ± SD: 13.1±3.8yrs) over a eight-year period. Age, gender, vertical craniofacial morphology and anatomical location of brackets were entered into Cox models as covariates. The findings indicated that bracket failure was significantly affected by tooth position within the dental arch, with the highest failure risk in maxillary posterior region. Age, gender and vertical craniofacial morphology did not affect bracket failure. A Cox proportional hazards model with a shared frailty term represents a useful approach for modelling orthodontic bracket failures.

Original languageEnglish
Pages (from-to)3483-3491
Number of pages9
JournalStatistics in Medicine
Volume28
Issue number28
DOIs
Publication statusPublished - Dec 10 2009

Fingerprint

Orthodontic Brackets
Survival Analysis
Brackets
Proportional Hazards Models
Frailty
Dental Bonding
Cox Proportional Hazards Model
Dental Arch
Tooth
Covariates
Term
Vertical
Survival
Observation
Frailty Model
Cox Model
Survival Data
Failure Time
Arch
Risk Factors

ASJC Scopus subject areas

  • Epidemiology
  • Statistics and Probability

Cite this

Petracci, E., Farella, M., Galeone, C., Albano, A., Ferraroni, M., & Decarli, A. (2009). Survival analysis with clustered observations of orthodontic brackets. Statistics in Medicine, 28(28), 3483-3491. https://doi.org/10.1002/sim.3641

Survival analysis with clustered observations of orthodontic brackets. / Petracci, Elisabetta; Farella, Mauro; Galeone, Carlotta; Albano, Alessandra; Ferraroni, Monica; Decarli, Adriano.

In: Statistics in Medicine, Vol. 28, No. 28, 10.12.2009, p. 3483-3491.

Research output: Contribution to journalArticle

Petracci, E, Farella, M, Galeone, C, Albano, A, Ferraroni, M & Decarli, A 2009, 'Survival analysis with clustered observations of orthodontic brackets', Statistics in Medicine, vol. 28, no. 28, pp. 3483-3491. https://doi.org/10.1002/sim.3641
Petracci E, Farella M, Galeone C, Albano A, Ferraroni M, Decarli A. Survival analysis with clustered observations of orthodontic brackets. Statistics in Medicine. 2009 Dec 10;28(28):3483-3491. https://doi.org/10.1002/sim.3641
Petracci, Elisabetta ; Farella, Mauro ; Galeone, Carlotta ; Albano, Alessandra ; Ferraroni, Monica ; Decarli, Adriano. / Survival analysis with clustered observations of orthodontic brackets. In: Statistics in Medicine. 2009 ; Vol. 28, No. 28. pp. 3483-3491.
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