Stent-aided imaging for osseointegrated implants

Volume70 Number 2 STENT-AIDED IMAGING FOR OSSEOINTEGRATED IMPLANTS 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 impor- tance because this measurement will allow the selec- tion of the proper numbers and diameters of implants. The true distance between the mental foramen is dif- ficult to assess because 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. 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 neces- sary, to improve stability. The radiograph is exposed in the usual manner (Fig. 2). Interpretation The radiographic length of the wire is measured. This di- mension is divided by the actual length of the wire to obtain the distortion factor. Distortion = Radiographic length of wire factor 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 OF THE MANDIBULAR CONDYLE F ractures of the condyle represent between 17%’ and 36%* of all fractures of the mandible. A compre- hensive review of the literature revealed only two Radiology forum 243 Fig. 1. Acrylic stent. Fig. 2. Pantomograph with stent seated. The interforaminal distance on the radiograph is then mul- tiplied by the distortion factor. This information will facil- itate 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 CASE REPORT 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 radiographi- case reports of sagittal condylar fractures.3y 4 tally demonstrable facial fractures, several facial lacera-

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Transcript of Stent-aided imaging for osseointegrated implants

Volume 70 Number 2

STENT-AIDED IMAGING FOR OSSEOINTEGRATED IMPLANTS

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 impor- tance because this measurement will allow the selec- tion of the proper numbers and diameters of implants. The true distance between the mental foramen is dif- ficult to assess because 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.

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 neces- sary, to improve stability. The radiograph is exposed in the usual manner (Fig. 2).

Interpretation

The radiographic length of the wire is measured. This di- mension is divided by the actual length of the wire to obtain the distortion factor.

Distortion = Radiographic length of wire factor 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 OF THE MANDIBULAR CONDYLE

F ractures of the condyle represent between 17%’ and 36%* of all fractures of the mandible. A compre- hensive review of the literature revealed only two

Radiology forum 243

Fig. 1. Acrylic stent.

Fig. 2. Pantomograph with stent seated.

The interforaminal distance on the radiograph is then mul- tiplied by the distortion factor. This information will facil- itate 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

CASE REPORT

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 radiographi-

case reports of sagittal condylar fractures.3y 4 tally demonstrable facial fractures, several facial lacera-