Читать книгу The Orthodontic Mini-implant Clinical Handbook - Richard Cousley - Страница 24

Concerns have been raised in the literature that mini‐implant perforation of the nasomaxillary cavities (Figure 1.3) may result in either infection or the creation of a fistula. However, the consensus based on dental implant research is that a soft tissue lining rapidly forms over the end of a perforating fixture, and that mini‐implant sites heal by bone infill because of the narrow width of the explantation hole. Motoyoshi et al. [51] investigated clinical effects in a retrospective study where 82 mini‐implants had been inserted mesial and buccal to the maxillary first molar [51]. They found perforation of the maxillary sinus in 10% of the sites, but with no sinusitis symptoms, nor differences in insertion torque and secondary stability. In contrast, a study of infrazygomatic insertions showed that 78% penetrated the maxillary sinus at this site [52]. Whilst these were apparently asymptomatic, mucosal thickening was seen on cone beam computed tomography (CBCT) in 88% of these sites where the mini‐implant penetrated by at least 1 mm. Therefore, in order to maximise bone engagement and minimise both patient discomfort and possible sinus disease, it is generally recommended that maxillary alveolar insertion sites should be within 8 mm of the alveolar crest in dentate areas, and at a more coronal level where maxillary molars are absent. The infrazygomatic crest is not recommended for this reason.

Figure 1.3 Coronal slice views of a CBCT scan of the maxilla (a) before and (b) one month after insertion of mini‐implants in palatal alveolar sites. The mini‐implant, sited distal to the right maxillary first molar, has been inserted at a relatively vertical inclination and has perforated the maxillary sinus, as seen in (b). However, this was asymptomatic and there has been no change in the clarity of the maxillary sinus.