The accuracy of image guided surgery based on cone beam computer tomography image data.

OBJECTIVE: The objective of this study was to verify if accurate patient-to-image registration for precision navigation in maxillofacial surgery is possible based on cone beam computed tomography (CBCT) image data. STUDY DESIGN: A maxillary registration template was placed on a standard plastic skull phantom that was equipped with a custom made model of the maxilla and with target markers. Imaging was performed with a CBCT device (Newtom 9000 Digital Volume Tomograph (DVT), QR s.r.l., Verona, Italy) and a computed tomography (CT) scanner (Somatom 4, Siemens, Forchheim, Germany). Using an infrared navigation system (Polaris, NDI, Waterloo, Ontario), multiple pair-point registration of both image data sets and the phantom were performed. The target registration error (TRE) was evaluated. RESULTS: A total of 243 registrations were performed for either image data set. The spatial distribution of TRE on the skull showed increasing inaccuracy with growing distance from the registration markers. The average target registration error was 1.50 +/- 0.82 mm with CBCT and 1.57 +/- 0.84 mm with CT image data and did not differ significantly. Error distribution correlated strongly between CT- and CBCT-based registration. CONCLUSIONS: The overall registration accuracy based on CBCT image data was similar to CT. The strong correlation of the geometric distribution of TRE between CT- and CBCT-based measurements proves that CBCT can be equivalent to CT in image-guided maxillofacial surgery.

Widening a narrow posterior mandibular alveolus following extirpation of a large cyst: a case treated with a titanium mesh-plate type distractor.

Vertical alveolar augmentation by distraction osteogenesis has become a standard pretreatment of dental implants due to the main benefit of lack of donor site complications, and many reports have shown its benefit with various types of alveolar distractors. However, autogenous bone transplantation and/or guided bone regeneration techniques are still the standard treatment for correcting a narrow alveolar ridge because of few commercially available distractors for alveolar widening. In this article, we treated a case by a mesh-plate type of alveolar widening distractor for a narrow posterior mandibular alveolar ridge after extirpation of a large jaw cyst.

Solitary congenital granular cell lesion of the tongue.

Congenital granular cell lesion (CGCL) is well known to appear as the congenital epulis, predominantly on the median maxillary alveolar ridge. This lesion rarely occurs on the tongue, and only 7 cases, including 4 cases with simultaneous occurrence on the alveolar ridge, have been reported in the English literature. In this report, we report a case of congenital granular cell lesion seen on the tongue. The patient was a 7-day-old Japanese girl who presented with a polypoid mass on the anterior ventral surface near the tip of the tongue. The lesion was excised at 4 months, and its histological examination revealed large granular cells. Immunochemical staining by S-100 was negative, and it was diagnosed as congenital granular cell lesion.

Multiple leiomyomatous hamartoma in the oral cavity.

Leiomyomatous hamartoma (LH) is congenital lesion rarely seen in oral cavity. In English literature, all reported cases appeared as solitary lesion in alveolar ridge or the tongue, and there have never been a report showing a case of multiple occurrence of this lesion. A quite rare case of multiple LH occurred in a 2-year-old Japanese boy is presented. A polypoid lesion was presented at incisive papilla and two isolated lesions in the tongue dorsum, one appeared as a polypoid mass in the posterior dorsum and other as a small spindle-shaped agger in the anterior dorsum. All of them were histologically diagnosed as LH.

Effects of subglottal air pressure on velopharyngeal muscle activity in dogs.

OBJECTIVE: To analyze the effects of airflow in the larynx on activity of the levator veli palatini and pterygopharyngeal muscles. DESIGN: Ten adult beagle dogs were anesthetized with sodium pentobarbital. In each dog, two tracheal tubes were inserted subsequent to tracheotomy, one in the direction of the vocal folds and the other toward the lungs for respiration. In the first of three experiments, the effect of artificial airflow on electromyographic activity of the levator and pterygopharyngeal muscles was studied. In the second experiment, the effect of air pressure beneath the vocal folds on the activity of these muscles was studied. For the third experiment, the larynx was isolated surgically without cutting the bilateral superior laryngeal nerves and the effect of airflow through it examined. RESULTS AND CONCLUSION: Both outward airflow and higher pressure enhanced expiratory activity of the levator and pterygopharyngeal muscles. Receptors in the subglottal area play major roles in this enhancement. Furthermore, an increase in air pressure during expiration enhances closure of the velopharynx.