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Stent-aided imaging for osseointegrated implants
Radiology forum
Volume70 Number 2 STENT-AIDED IMPLANTS
IMAGING
243
FOR OSSEOINTEGRATED
T
he pantomograph furnishes information on the location of important anatomic structures, including the inferior border of the mandible, the nasal cavity, the maxillary sinuses, the mandibular canals, and the mental foramen, structures to avoid damaging during osseointegrated implant therapy. For the mandible, the interforaminal distance is of particular importance because this measurement will allow the selection of the proper numbers and diameters of implants. The true distance between the mental foramen is difficult to assessbecause of the possibility of horizontal magnification or narrowing of the image in the radiograph. A method to overcome this problem by the use of a radiographic stent is described.
Fig.
1. Acrylic stent.
Procedure
A stent is fabricated on a diagnostic cast with the use of clear polymethyl methacrylate. A wire of known length (usually 50 mm) is embedded into the stent along the crest of the residual ridge (Fig. 1). The stem is placed in the patient’s mouth with the help of a denture adhesive, if necessary, to improve stability. The radiograph is exposed in the usual manner (Fig. 2). Interpretation
The radiographic length of the wire is measured. This dimension is divided by the actual length of the wire to obtain the distortion factor. Distortion factor
= Radiographic length of wire Actual length of wire
Conclusion
With the use of the distortion factor, the actual distance between the mental foramen can be determined. If the distortion factor is greater than one, the image is magnified. In such cases,the radiographic distance between the mental foramen is divided by the distortion factor to yield the actual distance between the mental foramen. If the distortion factor is less than one, the image is narrowed horizontally.
SAGITTAL FRACTURE OF THE HEAD MANDIBULAR CONDYLE
Fig.
2. Pantomograph with stent seated.
The interforaminal distance on the radiograph is then multiplied by the distortion factor. This information will facilitate calculation of the exact number and size of the implants to be used. Joseph Steele, DiUD Zafrulla Khan, RDS Martin Steiner, DDS Allan G. Furman, BDS, PhD School of Dentistry University of Louisville Louisville, KY 40292
OF THE CASE REPORT
F ractures of the condyle represent
between 17%’ and 36%* of all fractures of the mandible. A comprehensive review of the literature revealed only two case reports of sagittal condylar fractures.3y 4
A 47-year-old white man was admitted to the Trauma Intensive Care Unit of our hospital after a motor vehicle accident in which his van hit a tree. The patient’s injury complex consisted of multiple clinically and radiographitally demonstrable facial fractures, several facial lacera-
Volume70 Number 2 STENT-AIDED IMPLANTS
IMAGING
243
FOR OSSEOINTEGRATED
T
he pantomograph furnishes information on the location of important anatomic structures, including the inferior border of the mandible, the nasal cavity, the maxillary sinuses, the mandibular canals, and the mental foramen, structures to avoid damaging during osseointegrated implant therapy. For the mandible, the interforaminal distance is of particular importance because this measurement will allow the selection of the proper numbers and diameters of implants. The true distance between the mental foramen is difficult to assessbecause of the possibility of horizontal magnification or narrowing of the image in the radiograph. A method to overcome this problem by the use of a radiographic stent is described.
Fig.
1. Acrylic stent.
Procedure
A stent is fabricated on a diagnostic cast with the use of clear polymethyl methacrylate. A wire of known length (usually 50 mm) is embedded into the stent along the crest of the residual ridge (Fig. 1). The stem is placed in the patient’s mouth with the help of a denture adhesive, if necessary, to improve stability. The radiograph is exposed in the usual manner (Fig. 2). Interpretation
The radiographic length of the wire is measured. This dimension is divided by the actual length of the wire to obtain the distortion factor. Distortion factor
= Radiographic length of wire Actual length of wire
Conclusion
With the use of the distortion factor, the actual distance between the mental foramen can be determined. If the distortion factor is greater than one, the image is magnified. In such cases,the radiographic distance between the mental foramen is divided by the distortion factor to yield the actual distance between the mental foramen. If the distortion factor is less than one, the image is narrowed horizontally.
SAGITTAL FRACTURE OF THE HEAD MANDIBULAR CONDYLE
Fig.
2. Pantomograph with stent seated.
The interforaminal distance on the radiograph is then multiplied by the distortion factor. This information will facilitate calculation of the exact number and size of the implants to be used. Joseph Steele, DiUD Zafrulla Khan, RDS Martin Steiner, DDS Allan G. Furman, BDS, PhD School of Dentistry University of Louisville Louisville, KY 40292
OF THE CASE REPORT
F ractures of the condyle represent
between 17%’ and 36%* of all fractures of the mandible. A comprehensive review of the literature revealed only two case reports of sagittal condylar fractures.3y 4
A 47-year-old white man was admitted to the Trauma Intensive Care Unit of our hospital after a motor vehicle accident in which his van hit a tree. The patient’s injury complex consisted of multiple clinically and radiographitally demonstrable facial fractures, several facial lacera-