Mandibular overdentures retained by 1 or 2 implants: a 5-year randomized clinical trial on implant stability and peri-implant outcomes.

AIM: This is a report of the 5-year results of a two-group parallel randomized clinical trial comparing longitudinal implant stability, and clinical and radiographic peri-implant outcomes of mandibular overdentures retained by one (1-IOD group) or two (2-IOD group) implants. METHODS: All participants received 4.1 mm diameter tissue-level implants (Straumann® Standard Plus - SLActive®, Institut Straumann AG), installed in the mandible midline (1-IOD; n = 23) or the lateral incisor-canine area bilaterally (2-IOD; n = 24), and loaded after 3 weeks. Implant Stability Quotient (ISQ) was measured using a resonance frequency device (Osstell® Mentor, Integration Diagnostics) at implant placement, after three weeks (loading), and at the 6-month, 1-, 3-, and 5-year follow-ups. Marginal bone loss and clinical implant outcomes (plaque, calculus, suppuration and bleeding) were assessed periodically up to 5 years after loading. RESULTS: Only minor changes in marginal bone level were observed after 5 years (mean = 0.37; SD = 0.44 mm), and satisfactory and stable peri-implant parameters were observed throughout the 5-year follow-up. No significant differences between groups were found. Overall, the mean primary implant stability was considered high (> 70) for the two groups (1-IOD = 78.1 ± 4.5; 2-IOD = 78.0 ± 5.8). No noticeable changes were observed between implant insertion and loading. A marked increase was observed from insertion to the 6-month follow-up - the mean difference for the 1-IOD group was + 5.5 ± 5.5 (Effect size = 1.00), while for the 2-IOD group, the mean difference was + 6.0 ± 5.6 (Effect size = 1.08). No relevant changes were observed throughout the follow-up periods up to 5 years. Linear mixed-effect model regression showed no influence of the bone-related variables (p > 0.05) and the number of implants (p = 0.087), and a significant effect of the time variable (p < 0.001). CONCLUSION: Satisfactory peri-implant outcomes and stable secondary stability suggest good clinical performance and successful long-term osseointegration of the implants for single and two-implant mandibular overdentures. Using a single implant to retain a mandibular overdenture does not seem to result in detrimental implant loading over the five years of overdenture use. CLINICAL RELEVANCE: This study corroborates the use of a single implant to retain a mandibular denture.

Prosthodontic outcomes of mandibular overdenture treatment with one or two implants: 4-year results of a randomized clinical trial.

OBJECTIVE: To assess the incidence of prosthodontic maintenance events and complications during 4 years of follow-up after mandibular overdenture treatment with one or two implants. METHODS: Participants received one or two implants inserted in the midline (1-IOD group) or the lateral incisor-canine area bilaterally (2-IOD group). Implants were loaded with an early loading protocol after 3 weeks. Programmed recall visits were scheduled at the 6-, 12-, 36-, and 48-month follow-ups and nonprogrammed visits in case of prosthodontic complaints. The type of maintenance was registered, and the final treatment outcome was classified as successful, surviving, unknown, dead, repair, or retreatment. RESULTS: Forty-seven participants, mean age 65.4 ± 8.6, 74.5% female, were included (1-IOD = 23; 2-IOD = 24) and 44 completed the 4-year follow-up. A total of 159 prosthodontic maintenance events occurred and 89 in unscheduled visits. The most common event was the need for minor modifications of the denture base due to sore spots in the oral mucosa (n = 56 in 31 patients), matrix activation (n = 54 in 34 patients), and overdenture fracture (n = 25 in 18 patients). A "successful" or "surviving" outcome could be attributed to 57.5% of cases, whereas 38.3% needed repair. No significant differences in the incidence of prosthodontic events or treatment outcomes were found between the two groups. CONCLUSIONS: Findings show that 1-IODs perform similar to 2-IODs when considering the incidence of fractures and the need for prosthodontic maintenance, including adjustments of the overdenture and the attachment system.

Expected and perceived burdens in patients receiving mandibular overdentures retained by one or two implants.

PURPOSE: This study aimed to assess patients' expected burdens before treatment and their perceived burdens after the surgical and prosthodontic procedures of mandibular overdenture treatment and to evaluate factors influencing patients' perceptions. METHODS: Data were collected from 47 participants enrolled in a randomized clinical trial comparing mandibular overdentures retained by one or two implants. A 20-item questionnaire measured on a four-point Likert scale covering the surgical and prosthetic treatment procedures was used to assess the patients' perception of the procedural burdens before (expected burdens) and immediately after (experienced burdens) each procedure. Operators' perceptions of intercurrences associated with the procedures were also assessed as an independent variable. RESULTS: Low levels of perceived burdens were observed both before and after treatment. The mean overall scores of 1.65 ± 0.46 and 1.53 ± 0.33 for expected and experienced burdens, respectively, indicated that most items ranged between "not burdensome at all" and "somewhat burdensome." Significant differences between expected and experienced burdens were found for eight items (P < 0.001). Considering the treatment stages, expected burdens scored higher in the pre-surgical, surgical, and prosthetic stages and lower in the post-surgical phase than experienced burdens. Overall, the experienced burdens were significantly affected by the expected burdens (P < 0.001) and operator's perceived burdens(P = 0.045). CONCLUSIONS: Treatments were associated with low levels of perceived burdens related to surgical and prosthodontic procedures and were highly correlated with the expected burdens before treatment. However, patients tend to overestimate the expected burdens before treatment, especially for surgical procedures.

Postsurgical oral symptoms after insertion of one or two implants for mandibular overdentures: short-term results of a randomized clinical trial.

OBJECTIVE: This randomized clinical trial aimed to compare the short-term postsurgical symptoms after insertion of one or two implants for retention of a mandibular overdenture. This study investigated whether the less invasive single-implant approach results in lower postoperative symptoms compared to the conventional two-implant overdenture. MATERIALS AND METHODS: Patients received new complete dentures and were randomly assigned to groups receiving one or two single-stage, early-loaded hydrophilic implants, inserted in the midline (n = 23), or the lateral incisor-canine area bilaterally (n = 24). Patient-reported postoperative symptoms were measured in a 0-100 visual analogue scale concerning pain in the surgical area, pain when chewing, bleeding, swelling, and unpleasantness. Data collection occurred 24 h and 7 and 21 days after surgery. Demographic and clinical features (smoking habit, classification of the residual ridges, and mucosal width and thickness at the implant sites), osteotomy for alveolar bone reduction, and surgery time were tested as predictors of symptom levels. RESULTS: Overall reported symptoms were mild and self-limited, with high rates of complete remission after the early loading period of 3 weeks. Progressive improvement of symptoms occurred from the 24-h to the 7-day and 21-day follow-ups (p < 0.001), similarly in both groups. None of the clinical predictors was significantly associated with the changes in symptoms. CONCLUSIONS: Findings suggest that the insertion of one or two implants may result in similar postoperative outcomes. CLINICAL RELEVANCE: The severity of short-term postoperative symptoms may not be a critical factor for the decision between overdenture treatment with one or two implants.

Single versus two-implant mandibular overdentures using early-loaded titanium-zirconium implants with hydrophilic surface and ball attachments: 1-year randomized clinical trial.

OBJECTIVE: This randomized clinical trial aimed to compare the outcomes of the mandibular overdenture retained by one (1-IOD) or two (2-IOD) implants. MATERIALS AND METHODS: Participants received new complete dentures, were assessed at baseline and randomly assigned to groups. Early loaded single midline implant (1-IOD) or two implants in the canine regions bilaterally (2-IOD). Ball attachments were used for overdenture retention. Post-treatment outcomes (6- and 12-month follow-ups) included patient satisfaction, oral health-related quality of life measures, and chewing function. Data analysis included within- and between-group comparisons, and Generalized Estimating Equations. Both superiority and non-inferiority hypotheses were tested. RESULTS: Forty-seven participants were included (1-IOD = 23; 2-IOD = 24). Significant improvements in OHIP-Edent were observed after insertion of new dentures and at the 1-year follow-up compared with baseline. No differences were found between the 1- and 2-IOD groups for the OHIP-Edent and QoLFAST scores. Patient satisfaction with the mandibular denture improved significantly from baseline to the 6-month follow-up and remained unaltered until 1 year, with no differences between groups. The magnitudes of treatment effect sizes were moderate to large for patient-reported outcomes. Progressive improvement in chewing function occurred in both groups. Non-inferiority testing based on a 15% non-inferiority margin showed inconclusive results for patient-reported outcomes, whilst chewing function in the 1-IOD group was concluded to be not inferior to the 2-IOD group. CONCLUSIONS: Results support the use of both 1- and 2-IOD. The 1-IOD was also an acceptable alternative to the 2-IOD as a secondary option for the treatment of the edentulous mandible.