Site selection of micro-implant anchorages in the infrazygomatic crest in adult orthodontic patients

OBJECTIVES

To determine the optimal placement of miniscrews, this study compared adult male and female patients in terms of cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest region.

METHODS

The cone beam computed tomography imaging data of 200 patients (20-30 years old; 100 males and 100 females) were collected. The right maxillary posterior teeth in the sagittal plane were divided into six levels from proximal to distal, and three measurement sites were positioned at vertical distances of 8, 10, and 12 mm from the cementum. Cortical bone density, cortical bone thickness, and available bone width were measured in 18 measurement sites in the infrazygomatic crest and analyzed statistically.

RESULTS

The highest cortical bone density, cortical bone thickness, and available bone width in the infrazygomatic crest in adult male and female patients were at the level of the interradicular space between the maxillary second premolar and maxillary first molar. The bone cortical density and thickness increased with vertical height, whereas the available bone width decreased with increasing vertical height. Differences were observed in cortical bone density, cortical bone thickness, and available bone width between adult male and female patients.

CONCLUSIONS

The optimal implantation sites of the micro-implant anchorages in the infrazygomatic crest were at the level of the interradicular space between the maxillary second premolar and the maxillary first molar, and the vertical height of the optimal implantation site in males was appropriately higher than that in females.

Should Cone-Beam Computed Tomography Be Performed Prior to Orthodontic Miniscrew Placement in the Infrazygomatic Crest Area?-A Systematic Review

There is no unequivocal scientific consensus for the temporary anchorage device (TAD) positioning in the infrazygomatic crest area (IZC). The two principal aims of this systematic review were to assess bone availability in the IZC and to establish both the target site and the need for cone-beam computed tomography (CBCT) prior to miniscrew placement. The study was performed following PRISMA guidelines (PROSPERO: CRD42023411650). The inclusion criteria were: at least 10 patients, three-dimensional radiological examination, and IZC assessment for the TAD placement. ROBINS-I tool and Newcastle-Ottawa Scale were used for quality evaluation. No funding was obtained. The study was based on the information coming from: PubMed, Google Scholar, Web of Science Core Collection, MDPI, Wiley, and Cochrane Libraries. The last search was carried out on 1 August 2023. Fourteen studies were identified for analysis. A narrative synthesis was performed to synthesize the findings of the different studies. Unfortunately, it is not possible to establish the generally recommended target site for IZC TAD placement. The reasons for this are the following: heterogeneity of available studies, inconsistent results, and significant risk of bias. The high variability of bone measurements and the lack of reliable predictors of bone availability justify the use of CBCT for TAD trajectory planning. There is a need for more high-quality studies aiming three-dimensional bone analysis of the IZC.

Infrazygomatico-coronoid fixation in a segmental mandibular reconstruction with a free vascularized flap: A simple and correct repositioning method without interfering with reconstructive and microsurgical procedures

BACKGROUND

In a segmental mandibular reconstruction with a free vascularized flap, reproducing the optimal relationship between the condyle and glenoid fossa, and maintaining correct occlusion are important. We examined the practicality of a repositioning technique that combined bone plate fixation of the infrazygomatic crest and the coronoid process (infrazygomatico-coronoid fixation [IZCF]) with maxillo-mandibular fixation (MMF).

METHODS

Eight patients were treated with this method. To investigate masticatory function, the status of the dental and temporomandibular joints were examined, and a food scale questionnaire was administered.

RESULTS

IZCF and MMF resulted in correct repositioning of the segmented mandibles and enabled accurate reconstructions. Most patients recovered to be able to ingest the same preoperative food in scale with stable occlusion.

CONCLUSION

This method is a simple and correct repositioning method without interfering with reconstructive and microsurgical procedures. We propose this technique as a reliable method for obtaining a functional outcome in mandibular reconstruction. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1708-1716, 2016.