34 Chapter 2 Patient related outcome measures: between group comparison The between groups PROMs comparison is listed in Table 2.5 and did not result in significant differences between the groups for any individual questionnaire items or the Total OHIP-NL49 score. Considering the functional complaints questionnaire, both groups were equally satisfied with their maxillary overdenture. Despite chewing in general, as well as chewing tough and hard foods favouring the bar group at the 1 year follow-up, these differences had balanced out by the five year follow-up. 2.4 DISCUSSION Based on the results of the present study’s 5-year follow-up period, a maxillary 4-IOD with a bar attachment system is the more favourable therapy for fully edentulous patients compared to a 4-IOD with a solitary attachment system, considering the significantly lower amount of marginal bone level change and significantly higher implant survival rate. Other studies Current maxillary 4-IOD research is mainly focused on retention with bars. Several prospective studies with a 5-year follow-up period reported high survival rates, ranging from 97.7% - 100%, combined with a low MBLC ranging from -0.2mm to -1.2mm after five years1-5, which are in line with the present study’s findings. The studies focusing on solitary attachments were mostly retrospective. Compared to bars, these studies showed a predominantly higher MBLC ranging from -0.4 to -1.7 mm, lower survival rates ranging from 92% to 98.9%, but a shorter mean follow-up period ranging from 32.9 – 58 months20-23. The only RCT on 4-IODs retained by solitary attachments, performed by Bouhy et al.24 reported a mean MBLC of -1.01 mm after one year, with a relatively low survival rate of 86.2%. There are two prospective studies available with a follow-up longer than 5 years. The first study compared 3-IOD with ball- or bar-attachments over a follow-up period of 10 years and reported a mean MBLC of -0.84 mm and a 87% survival rate, with no differences between the groups6. The low survival rate was mostly due to failed osseointegration (12 out of 16 implants). The second study reported 4-IODs with bars and solitary in a prospective cohort study with a mean follow-up of 11.4 years25. They reported a cumulative failure rate of 23.8%. Though more implants were lost by the solitary attachment group, the difference was not significant. Interestingly, most of the bar group’s implants failed in the first year after loading, while the solitary attachment group’s implant failure was more wide-spread, with 5 failures in the first year, 4 in the fourth year and 2 in the eleventh year. A similar failure pattern was observed in the present study. The effect of clinical parameters In the present study, the median plaque, bleeding, gingival and calculus scores and mean probing pocket depth change remained low throughout the entire follow-up period, which is in line with the findings of other studies1-3, and so we do not think it contributed to the differences in MBLC and implant loss found between the groups. Therefore, the idea that solitary attachments aid in easier oral hygiene could not be supported either. In fact, while the peri-
RkJQdWJsaXNoZXIy MTk4NDMw