Author: Dr Aparna Pandya (Mrs India Vivacious 2019)
Today, one of the common treatment modality for replacing missing teeth are dental implants. Dental implants are surgically inserted in the jawbones. Unfortunately, there are some limitations to the extent of use of dental implants. One of them, is the lack of sufficient bone volume, especially in the posterior maxilla. There are several techniques of increasing local bone volume. Some of the limitations of such techniques are the need for multiple surgical interventions, the use of extraoral bone donor sites (e.g., iliac crest or skull) and longer duration of healing period.
The placement of implants in the zygomatic bone as an alternative to maxillary reconstruction with autogenous bone grafts has been considered a good option in the rehabilitation of atrophic maxillae.
The zygomatic implants are self-tapping screws in titanium with a well-defined machined surface. They are available in eight different lengths ranging from 30 to 52.5 mm. They present a unique 45° angulated head to compensate for the angulation between the zygoma and the maxilla. The portion that engages the zygoma has a diameter of 4.0 mm and the portion that engages the residual maxillary alveolar process a diameter of 4.5 mm.
In addition to clinical examination, radiologic assessment has to be considered. The preferred method is CT since orthopantomography can give distorted information. The examination of choice is the spiral or helicoid computed tomography (CT) scan, which makes two- and three-dimensional imaging possible with axial cuts every 2 mm parallel to the palatal arch and conventional tomography with frontal tomograms perpendicular to the hard palate every 3-4 mm. The CT scan also gives the opportunity to visualize the health of the maxilla and the sinus. The density, length and volume of the zygoma can be evaluated and special templates for inserting the zygomatic implants can be constructed on stereolithographic models to facilitate the orientation of the zygomatic implants during the surgery with minimal errors in angulation and position.
The original procedure, defined by Branemark in 1998, consisted of the insertion of a 35-55 mm-long implant anchored in the zygomatic bone following an intra-sinusal trajectory. Stella and Wagner described a variant of the technique (Sinus Slot Technique) in which the implant is positioned through the sinus via a narrow slot, following the contour of the malar bone and introducing the implant in the zygomatic process. In this way, the need for fenestration of the maxillary sinus is avoided and the implant is caused to emerge over the alveolar crest at first molar level, with a more vertical angulation.
The reported complications associated with zygomatic implants include-postoperative sinusitis,
The zygomatic implant technique is a major surgical procedure and should be performed after proper training and under expert supervision. Zygomatic implants is an excellent and safe option for patients with advanced maxillary atrophy.
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