4. Discussion
peri-implant bone loss, edentulous, bone loss
BONE LOSS
Due to a lack of clinical evidence on whether the insertion of only three MDIs can be as equally successful of a treatment as the insertion of four MDIs for the retention of mandibular ODs over a longer period of time, this cohort study was set up. The 5-year results revealed small rates of peri-implant bone loss in both the three- and four-MDI groups, with no significant difference between them. The 5-year success and survival rates were also not different between the groups and were acceptable in both groups. Thus, the hypothesis was accepted.The short time of clinical evidence (one year) showed that either two or four MDIs led to better oral health-related quality of life (OHRQoL), compared with two standard implants [Our previous clinical experience showed that patients with four MDIs, even when they lost one implant, continued to wear dentures retained on only three MDIs. Therefore, as the less expensive treatment than the four MDIs, we chose to follow-up prospectively the option of inserting only three MDIs. The insertion of four MDIs is the standard of care for mandibular OD retention in edentulous subjects with narrow ridges [It is known that younger patients develop higher occlusal forces and chew more vigorously, while implants have less proprioception than periodontal ligaments [The keratinized mucosa thickness can influence the amount of marginal bone loss. It was reported that the peri-implant bone loss is lesser in thick than in thin mucosa biotypes [The limitations of the present study are the 2-dimensional assessment of peri-implant bone level, variations in the amount of chewing force between the participants, variations in the diameter (2.0–2.5) and length (10, 12 or 14 mm) of the MDIs, variations in the thickness of the keratinized mucosa around implants, as well as differences in the thickness of the mucosa at the overdenture’s bearing area, which could account to different levels of stress and strain around implants. The strength of this study is the long period of clinical follow-up (5 years) and the controlled cohort prospective study design.Overall, the findings of the present study point out that a treatment with only three MDIs is a clinically acceptable treatment option: the same as treatment with four MDIs [