Evaluation of bone thickness in the anterior hard palate relative to midsagittal orthodontic implants.

PURPOSE: The Straumann Orthosystem (Institut Straumann, Waldenburg, Switzerland) describes a technique that involves placement of titanium implants (4 or 6 mm long and 3.3 mm in diameter) into the midsagittal hard palate for orthodontic anchorage. The aim of this study was to determine the quantity of bone in the midline of the anterior hard palate, and specifically the thickness inferior to the incisive canal. MATERIALS AND METHODS: Twenty-five dry skulls were radiographed with a standardized cephalometric technique. The vertical thickness of the midsagittal palate was then measured to the nearest tenth of a millimeter. Next, gutta-percha was injected into the incisive canal, and the radiograph was repeated. The bone thicknesses were then measured from the inferior hard palate to the most Inferior part of the radiopaque canal. This is defined as the actual bone available for the implant without violating the canal. RESULTS: The measurements have shown that an average of 8.6 +/- 1.3 mm of bone is theoretically available for the implant. However, considering the canal (where only bone thickness inferior to it is utilized and measured), only 4.3 +/- 1.6 mm of bone exists. The canal itself averaged 2.5 +/- 0.6 mm in diameter. DISCUSSION: Prior studies have overestimated the amount of bone available for implants in the median hard palate. The main reason for this is that the incisive canal is not well visualized on cephalometric radiographs of live patients. CONCLUSION: This study supports the continued use of implants, as approximately 50% of skulls still had the requisite minimum 4 mm of bone inferior to the incisive canal for maximum osseointegration with the 4-mm implants. However, 6-mm implants should be used with caution.

Anatomical variations and clinical implications of the artery to the lingual nerve.

The pterygomandibular space is a critical anatomic area for the delivery of local anesthesia in the practice of dentistry. The neurovascular contents of this area are subject to trauma and its resultant local and systemic complications. This study of 202 cadaveric specimens reaffirms the literature as to the percent distributions of the superficial and deep routes of the maxillary artery and details for the first time the anatomic variations of the artery to the lingual nerve. This artery courses through the pterygomandibular space placing it at risk for injection trauma along with the other neurovascular contents. It has been uncommonly identified and referred to in the literature, yet it may be the first artery encountered when entering the space with a needle or during surgical intervention in the area.

The posterior superior alveolar injection technique: a report on technique variations and complications.

The posterior superior alveolar (PSA) injection technique has varied over time with respect to the depth and angle of penetration, the location for deposition of anesthetic agent, and the number of injections necessary to assure adequate anesthesia to the maxillary molars. Of the standard intraoral injections, the PSA carries with it the second highest risk for anesthesia complications. With changes in armamentarium and technique, the complication rates have declined and more often are associated with anatomical considerations with respect to neurovascular compromise and/or anesthetic solution. In this study, the PSA injection technique and complication histories were investigated. Seventeen variations to the technique are reported along with 12 injection complications. A historic injection complication classification system is presented along with a management strategy based upon a review of reported provider experiences and treatment suggestions.

The triangle of safety: a modified posterior superior alveolar injection technique based on the anatomy of the PSA artery.

The posterior superior alveolar (PSA) injection technique is commonly used to anesthetize soft and hard tissues of the posterior maxilla. As with all injections, complications arise, including hematoma formation secondary to needle-induced vascular trauma. In an attempt to develop a hemorrhage-free PSA injection technique, 361 infratemporal dissections were completed on human cadaver specimens. Three distribution patterns were identified for the external branch of the PSA artery. Regardless of distribution pattern, an anatomical Triangle of Safety was found superior to the maxillary second molar that was free of neurovascular tissues in more than 99% of individuals. Injection into this area appears to meet anesthetic needs while reducing the risk of hematoma formation. The combination of this anatomical triangle with newer anesthetic agents and computerized delivery systems holds promise for continued improvement of the PSA injection technique.