PHOTOGRAMMETRIC TECHNIQUES FOR DENTISTRY ANALYSIS, PLANNING AND
VISUALISATION
V. A. Knyaz *, S. Yu. Zheltov
State Research Institute of Aviation Systems (GosNIIAS), 125319, 7, Victorenko str., Moscow, Russia -
knyaz@gosniias.ru, zhl@gosniias.ru
Commission V, WG-V-6
KEY WORDS: Close-range Photogrammetry, Accuracy, Dentistry, Visualization
ABSTRACT:
Dentistry is a field which has a need for accurate information about teeth shape, their relative position and their appearance in the
face. This information is essentially important for various dentistry fields such as orthodontia, teeth treatment, denture production.
Existing methods for analyzing mutual teeth arches position (occlusion) use plaster teeth arches casts and a special mechanical tools
which allow registering occlusion. For investigation and visualization of exterior appearance of teeth arches only 2D images are
used which do not provide full and adequate presentation. So existing means do not give required accuracy and are not convenient
for a dentist. Photogrammetric approach gives solution for all described problems with appropriate accuracy of measurements and
high quality data for investigation, documentation and presentation. A set of new techniques for teeth occlusion registration and
analysis is proposed based on applying teeth arch 3D model instead of a plaster mould. The developed photogrammetric techniques
are used for automated patient face and teeth arch 3D models generation, for occlusion registration, treatment planning and
documenting.
1. INTRODUCTION
A lot of dentistry applications has a need for information about
teeth shape and the relative position of upper and lower dental
arches. This information is necessary for proper dental
treatment as long as for accurate and convenient denture
making. Most of the existing techniques for teeth measurement
and analyzing of mutual teeth arches position (occlusion) use
plaster teeth arches models for occlusion analysis and special
mechanical positioning device -articulator - to register jaws
position. For registering exterior appearance of the teeth (when
smiling, for example) 2D photograph is usually used which
could not give adequate and complete information.
A successful dentistry treatment is based on reliable
information about relative teeth arches position and mutual
location of teeth in different occlusions.
Tooth preparation is one of the key clinical procedures in
prosthetic dentistry which provides necessary conditions for
fixed prosthesis construction. Occlusal surface is the
functionally significant part of a chewing tooth. It is difficult to
observe it during functioning as when opposite (upper and
lower) teeth are in contact their occlusal surfaces can not be
seen. But a dentist has a need of knowing some distances
between corresponding teeth in given section. Existing methods
do not provide the required data. The only information which a
dentist can get about teeth position is knowing if there is
presence (or absence) of contact between upper and lower teeth.
This information can be obtained using thin colour sheet of
paper to mark off the place of contact on teeth (occlusion) when
closing jaws. And how dentures will correspond to the teeth
arch and a face could be analyzed after denture making.
For adequate prosthetic construction it is necessary to study
occlusal surface in connection with its structure and function, to
analyze results of occlusal surface preparation and to find
proofs or denials for occlusal surface preparation method.
New methods for tooth preparation based on a consideration of
tooth structure and its position in masticatory system will offer
key clinical approaches that ensure necessary and sufficient
quality in occlusal surface preparation. It allows producing
anatomically and functionally adequate fixed dentures i.e. full
and partial crowns and bridges, to make the process of
preparation more focused and to improve co-operation between
dentists and dental technicians.
It was found that bucco-lingual sections of teeth can clearly
manifest the results of the experimentfl study. Performing such
sections on plaster casts would require a large number of them
and their copies, a method of obtaining a graphic depiction of
sections and, due to the novelty of the preparation method, a
multitude of sections for getting the ones that are of interest.
Hence, such a study on plaster casts would become enormously
cumbersome and “bulky”. So a new a technique for occlusion
analysis is needed. The most attractive method for teeth surface
and relative position study is to use “virtual dentist’s office”
and operate with teeth arch 3D model instead of plaster mould.
Photogrammetric approach allows getting accurate and
convenient solution for concerned problems. Application of an
accurate teeth arch 3D model instead plaster mould gives to a
dentist new possibilities for occlusion analysis and visualization
of treatment forecast using patient’s face 3D model.
Proposed photogrammetric system supports all necessary
functions for teeth arches occlusion analysis. It uses specially
Corresponding author.
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