115 Maxillary implant overdentures: retreatment after failure Implant survival Three participants lost three implants within the first year of function, which resulted in an implant survival rate of 95.7% (Table 7.3). Two of these participants were former smokers who started smoking again after the surgical procedure. The loss of the implants had no prosthetic consequences, and no additional implants had to be placed. Marginal bone level change and clinical outcome measures The mean MBLC was -0.32 ± 0.46 mm after a mean of 3.3 years (Table 7.3). The peri-implant tissues were healthy and their mean PD was 4.55 ± 1.59 mm. (Table 7.4). Patient related outcome measures The results on PROMs are depicted in Table 7.4. The mean maxillary overdenture score was 8.7 ± 1.2 (max. 10). The median score for eating soft and tough foods was 0 (Q1-Q3: 0-0) and 0 (Q1-Q3: 0-0.5) respectively which correspond with ‘Good’. The median score for hard foods was 1 (Q1-Q3: 0-1) which corresponds with ‘Moderate’. The mean total OHIP-NL49 Score was 29.5 ± 33.3 (max. score: 196). 7.4 DISCUSSION The aim of the study was to assess implant retreatment in a group of patients with multiple maxillary late implant failures and good results were attained at both clinical and patient levels. Complications during augmentation were easily resolved and did not interfere with further treatment. The survival rate was in line with most recent publications on replaced implants 4,5,18, while lesser results were seen in the past6,7,10. The results provide a viable treatment option when considering implant retreatment of edentulous maxillae. Implant survival It was suggested that late failures, i.e. chronically infected sites, such as in the current study, could result in lower bone quality and quantity4,8, which might lead to a lower survival. The current high survival rates contradict this proposition. In this study, the affected sites were reconstructed and allowed to heal prior to implant retreatment, which is in line with Al Saadi et al.19, who stated that bone augmentation can aid in a better prognosis. Retreated sites are often subjected to the same patient specific factors, such as general health, oral hygiene and smoking. Patients who lost an implant in this study had sufficient oral hygiene and were healthy. Two of three failed implants were in smokers. Smoking is not yet considered as a contra-indication for implant surgery20, but the negative effect seems to be clear21,22. Interestingly, all the failed implants were in patients with an opposing natural dentition. A review of the literature on this topic gives conflicting results, but the possible negative effect of an opposing (partial) dentition has been stated23. The results of a more recent study on maxillary overdentures with opposing dentitions24 are comparable with those from edentulous mandibulae25,26, which contradicts the effect of opposing dentitions and is not in line with the current findings. 7
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