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International Poster Journal of Dentistry and Oral Medicine
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Int Poster J Dent Oral Med 4 (2002), No. 3     15. Sep. 2002

Int Poster J Dent Oral Med 2002, Vol 4 No 3, Poster 138

Evolution of the incisal relationship in a Central European population (1870/1970)

Language: English

Authors: Dr. Olivier Laplanche MD, assistant professor1, Dr. Michel Laurent MD, assistant professor1, Dr. Jean Daniel Orthlieb MD, associate professor1, Dr. Erwin Jonke MD, associate professor3, Pr Otto Vizlozyl MD, professor3, Pr Olivier Dutour, professor4
1Professor Faculté d'Odontologie de Marseille
2Faculté d'Odontologie de Vienne (Autriche)
4Faculté de Médecine de Marseille

Date/Event/Venue: 
November 2000
ADF FDI 2000
Paris

The relationship between the upper and lower incisors is one of the keys to occlusal organisation and can be evaluated by:

  • occlusal and markers: overbite and overjet
  • skeletal markers: cephalometric values

Phylogenetic analysis of the incisal relationship and of the occlusion suggests, however, that anterior guidance recent variations in relation with environemental factors 


Material and Method

The material consisted of a series of dental cast (Fig. 1) and lateral cephalometric X ray (Fig. 2), of young men average age 25 years, caucasian type from central europe, displayed in two groups:
i) the 1870 group (Gr. 1870) data were 30 randomised subjects from 133 male skulls of soldiers who had served in the Austro-Hungarian army. They were all born circa 1870 and died of disease at around 25 years of age (the skulls form part of the Weisbach collection, Vienna, Austria).
ii) the 1970 group (Gr. 1970) data were 30 randomised subjects from 170 male conscripts to the Austrian Federal Army born in circa 1970, in the same region as the previous group, and of an average age of 20 years at the time of study.

Maxillary and mandibulary cast in centric occlusion were used to measure Over-bite and Over-jet with a calliper rule. (Fig. 3)
Cephalometric measurement were made and the 52 points needed for computer analysis were marked (Fig. 4). These data were entered into the computer using a scanner and the computer analysis was performed. The different values (angles and distances) for the incisal relationship were retained (Table 1)

Fig. 1: Plaster models in centric occlusion

Fig. 2: Lateral cephalometric X ray

Fig. 3: Anthropometric measurements: overbite and overjet

Fig. 4: 52 cephalometric points were used to analyse the determinant of incisal relationships

Inter-incisal angle
Angle between upper incisor and A-pogonion
Angle between upper incisor and PAO (axial-orbital plane)
Position of upper incisor in relation to the tangent
Supra-occlusion (upper incisor / occlusal plane)
Lower incisor to PAO
Angle of lower incisor in relation to A pogonion
Angle of lower incisor in relation to mandibular plane
Horizontal values of lower incisor to PAO
Vertical values of lower incisor to PAO
Position of lower incisor in relation to the tangent
Position of lower incisor in relation to A Pogonion
Inclination of upper incisor
Position of lower incisor
Egression of lower incisor
Skeletal Class
SNB, ANB, SNA, FMIA angles
SNA angle
ANB angle
FMIA angle
Radius of the curve of Spee
Table 1: Cephalometric values studied.

 

Statistical analysis
The cephalometric and anthropometric measurements were compared between populations using parametric tests for large sample size and the distribution of skeletal class was determined using the Chi squared test. 


Results

A statistically significant difference was found for the following variables (p<0.001):

  • Overbite (Fig. 5)
  • The FMIA (Fig. 6)
  • Position of the free edge of the mandibular incisor Sagittal and Vertical Value (Fig. 7)
  • Distribution in Skeletal class (Fig. 8)
Fig. 5: Overbite evolution

Fig. 6: FMIA evolution

Fig. 7: Evolution of Position of the free edge of mandibular incisor X (sagittal) value

Fig. 8: Skeletal class: evolution of distribution

  Gr. 1870
Average (S.T.)       
Gr. 1970
Average (S.T.)       
 
Overbite 1.17 mm (1.97) 3.81 mm (1.45) Fig. 5
The FMIA angle 65.97° (8.83) 58.4° (7.85) Fig. 6
Position of the free edge of the
mandibular incisor Sagittal Value  
78.75 mm (6.54) 82.88 mm (6.76) Fig. 8  
Vertical value 54.74 mm (5.82) 58.87 mm (8.21) Fig. 8
Skeletal class See distribution Fig. 7
Table 2: Results

 

Conclusion

In the limits of this study, the overall tendency amongst this population of young Western European males was to mandibular retrusion, vestibuloversion of the mandibular incisors and caudalisation of the free edge of mandibular incisors and overbiting. 


This poster was submitted by Dr. Olivier Laplanche.

Correspondence address:
Dr. Olivier Laplanche
23 boulevard PAOLI
20200 BASTIA
FRANCE