Miguel de Araújo Nobre

The use of computer-guided flapless implant surgery and four implants placed in immediate function to support a fixed denture: Preliminary results after a mean follow-up period of thirteen months

STATEMENT OF PROBLEM There is a need for clinical evidence for the of use of computer tomography and CAD-CAM technology for surgical planning and fabrication of a custom surgical template in the rehabilitation of complete edentulous jaws with a prosthesis supported by 4 implants placed in immediate function. PURPOSE The purpose of this study was to report on the preliminary clinical outcomes of survival and bone loss for prosthodontic rehabilitation using computer-guided flapless implant surgery and 4 implants placed in immediate function to support a fixed denture. MATERIAL AND METHODS This clinical study included 23 consecutively treated patients (18 maxillae and 5 mandibles). Ninety-two implants were placed supporting fixed complete dentures followed between 6 and 21 months (mean of 13 months). Recall examinations included clinical evaluation of implant mobility, patient-reported discomfort, suppuration, and infection. The radiographic assessment included the determining of the marginal bone level at 6 and 12 months. A cumulative implant survival rate was calculated, and data were analyzed with descriptive statistics. RESULTS The overall cumulative implant survival rate at 1 year was 97.8%, with 97.2% and 100% in the maxilla and the mandible, respectively. The average marginal bone loss was 1.9 mm at the 1-year follow-up. CONCLUSIONS The results of this study indicate that, within the limitations of this preliminary study, this treatment modality for completely edentulous jaws is predictable with a high survival rate.

“All‐on‐4” Immediate‐Function Concept for Completely Edentulous Maxillae: A Clinical Report on the Medium (3 Years) and Long‐Term (5 Years) Outcomes

BACKGROUND Immediate implant function has become an accepted treatment modality for fixed restorations in totally edentulous mandibles, whereas experience from immediate function in the edentulous maxilla is limited. PURPOSE The purpose of this study was to report on the medium- and long-term outcomes of a protocol for immediate function of four implants (All-on-4, Nobel Biocare AB, Göteborg, Sweden) supporting a fixed prosthesis in the completely edentulous maxilla. MATERIALS AND METHODS This retrospective clinical study included 242 patients with 968 immediately loaded implants (Brånemark System TiUnite, Nobelspeedy, Nobel Biocare AB) supporting fixed complete-arch maxillary all-acrylic prostheses. A specially designed surgical guide was used to facilitate implant positioning and tilting of the posterior implants to achieve good bone anchorage and large interimplant distance for good prosthetic support. Follow-up examinations were performed at 6 months, 1 year, and thereafter every 6 months. Radiographic assessment of the marginal bone level was performed after 3 and 5 years in function. Survival was estimated at patient level and implant level using the Kaplan-Meier product limit estimation with 95% confidence intervals. RESULTS Nineteen immediately loaded implants were lost in seventeen patients, giving a 5-year survival rate estimation of 93% and 98% at patient and implant level, respectively. The survival rate of the prosthesis was 100%. The marginal bone level was, on average, 1.52 mm (standard deviation [SD] 0.3 mm) and 1.95 mm (SD 0.4 mm) from the implant/abutment junction after 3 and 5 years, respectively. CONCLUSION The high survival rates at patient and implant level indicates that the immediate-function concept for completely edentulous maxillae using the present protocol is viable in the medium- and long-term outcomes.

A new approach to rehabilitate the severely atrophic maxilla using extramaxillary anchored implants in immediate function: A pilot study

STATEMENT OF PROBLEM There is a need to simplify implant treatment for complete arch rehabilitation of severely atrophic maxillae, as well as a desire to eliminate grafting and provide quality rehabilitation in terms of esthetics, function, and comfort for the patient. PURPOSE The purpose of this study was to report on the initial results of rehabilitation of complete edentulous atrophied maxillae using a new surgical approach and a newly designed extra long implant, placed externally to the maxillary bone (implant only accommodated in the maxillary bone) and anchored in the zygomatic bone. MATERIAL AND METHODS The pilot study included 29 patients (21 women and 8 men), with an age range of 32-75 years (mean=52.4 years), followed between 6 and 18 months, with a mean follow-up time of 1 year. The patients presenting severe atrophy in the maxillae (Cawood and Howell classification C-VI and D-V or D-VI) were rehabilitated either by using 1, 2, or 4 extra long implants (30 to 50 mm in length; Nobel Biocare AB) placed in the zygomatic bone in conjunction with standard implants (24 patients): or 4 extra long implants (5 patients), all placed in immediate function. The criteria used to evaluate implant outcome were: implants function as support for reconstruction; implants stable when individually and manually tested; no signs of infection observed; and good esthetic outcome of the rehabilitation. To evaluate the secondary objective of assessing the stability and health of the soft tissue covering the implants, the mucosal seal efficacy evaluation index (MSEE) was used. This index was modified from the probing depth for standard implants and performed with a 0.25-N calibrated plastic periodontal probe measuring the depth (mm) of the space between the implant and the mucosa. Data were analyzed with descriptive and inferential analyses. RESULTS The cumulative implant survival rate and prosthetic survival rate at 1 year were 98.5% and 100%, respectively. The mean and median values of the MSEE at 2 months (2.9 mm, 3 mm), 4 months (2.5 mm, 2.8 mm), 6 months (2.9 mm, 2.8 mm), and 1 year (2.8 mm, 2.5 mm) are comparable to the values of probing depths assessed for standard implants. CONCLUSIONS The results indicate that, within the limitations of this preliminary study, the rehabilitation of maxillae with severe atrophy can be performed using extra long implants placed external to the maxilla and anchored only in the zygomatic bone, and placed in immediate function.

Implants placed in immediate function in periodontally compromised sites: A five-year retrospective and one-year prospective study

STATEMENT OF PROBLEM Placing implants in periodontally compromised sites is generally considered a risk factor. Good results have been reported when rehabilitating partial or complete edentulous sites in patients with a history of periodontitis. However, there is a need for more documentation of this treatment modality. PURPOSE The purpose of this study was to report, retrospectively, on the placement of implants in periodontally compromised areas of the maxilla and mandible without a prior healing period and in immediate function. This study also presents a prospective preliminary 1-year report using a standardized clinical protocol, including a regenerative surgical procedure, control of the inflammatory response, a maintenance protocol, and use of an implant with an oxidized surface. MATERIAL AND METHODS The clinical study encompassed 184 consecutively included patients with 433 implants (165 with a machined surface and 268 with an oxidized surface) placed in immediate function (140 in the maxilla and 293 in the mandible) supporting 218 fixed prostheses. Two groups were defined: the Retrospective group (using an unstandardized surgical technique and a majority of machined surface implants) with a retrospective approach and the Prospective group (using standardized surgical and maintenance protocols and oxidized surface implants) with a prospective approach. The 2 groups were evaluated for implant survival, clinical implant stability, bone resorption, absence of radiolucent areas around implants on the radiographs, and patient-reported function of the implants. Definitive prostheses were placed 6 months after the surgery. The data was analyzed using descriptive statistics. RESULTS Thirteen implants were lost in 9 patients, providing a cumulative survival rate of 91% at 5 years for the Retrospective group. In the Prospective group, a 100% cumulative survival rate was recorded after 1 year. The average bone resorption (SD) was 1.2 mm (0.9 mm) and 1.1 mm (1.1 mm) after the first year for the Retrospective and Prospective groups, respectively, and 1.7 mm (1.0 mm) for the Retrospective group after the fifth year of function. CONCLUSIONS The cumulative survival rate of 91% at 5 years for the Retrospective group is low compared to protocols for noncompromised situations, but the use of a standardized protocol together with oxidized surface implants seems to improve the treatment outcome and bring the survival rate to levels comparable to noncompromised situations.

Retrievable Metal Ceramic Implant-Supported Fixed Prostheses with Milled Titanium Frameworks and All-Ceramic Crowns: Retrospective Clinical Study with up to 10 Years of Follow-Up

PURPOSE The purpose of this study was to report on the outcome of metal ceramic implant-supported fixed prostheses with milled titanium frameworks and all-ceramic crowns. MATERIALS AND METHODS The clinical study included 108 patients (67 women, 41 men), mean age of 58.6 years (range: 34-82), followed between 9 months and 10 years (post occlusal loading). The mean follow-up time for all patients in the study was 5 years. A total of 125 prostheses were fabricated. The data were divided into 2 groups. Development group (DG): 52 patients with 66 prostheses (28 maxillary, 38 mandibular) fabricated with individual Procera crowns (Alumina copings, Nobel Biocare AB) and Allceram ceramics (Ducera Dental GmbH) cemented onto a CAD/CAM fabricated Ti framework (Nobel Biocare AB) with pink ceramic (Duceram, Ducera Dental GmbH) that replicated the missing gingival tissues. Routine group (RG): 56 patients with 59 prostheses (49 maxillary, 10 mandibular) fabricated with individual Procera crowns (Zirconia copings and Nobel Rondo Zirconia Ceramic; Nobel Biocare AB) cemented onto a CAD/CAM fabricated Ti framework (Nobel Biocare AB) with pink acrylic resin (PallaXpress Ultra, Heraeus Kulzer GmbH) that replicated the missing gingival tissues. Primary outcome measures were prosthetic survival and mechanical complications. Secondary outcome measures were biological complications testing the retrievability characteristic of the prosthesis. Survival estimates were calculated on the patient level with the Kaplan-Meier product limit estimator (95% confidence intervals [CI]). Data were analyzed with descriptive and inferential analyses. RESULTS The cumulative survival rates for the implant-supported fixed prostheses were 92.4% for the DG at 10 years and 100% for the RG at 5 years (overall 96%) (Kaplan-Meier). Mechanical complications occurred in 44 patients (DG: 29 patients, 36 prostheses; RG: 15 patients, 16 prostheses); the large majority were crown fractures, occurring in 48 patients (DG: 33 patients, 36 prostheses; RG: 15 patients, 16 prostheses). In the DG, univariate analysis of logistic regression disclosed the presence of a metal ceramic implant-supported fixed prosthesis opposing dentition as a risk factor for crown fracture (OR = 1.97). Biological complications occurred in 33 patients (DG: 18 patients; RG: 15 patients), the majority being peri-implant pathologies in 19 patients (DG: 9 patients, RG: 10 patients). All situations were resolved except one in the DG that led to fixture and prosthesis loss. CONCLUSIONS The results of this study indicated that, within the limitations of this study, the CAD/CAM protocol is acceptable for definitive prosthetic rehabilitation. This protocol provided these patients with a good prognosis on a middle- to long-term basis (5 years).

All‐on‐4® Treatment Concept for the Rehabilitation of the Completely Edentulous Mandible: A 7‐Year Clinical and 5‐Year Radiographic Retrospective Case Series with Risk Assessment for Implant Failure and Marginal Bone Level

BACKGROUND Studies are needed to evaluate long-term outcomes of the All-on-4® treatment concept (Nobel Biocare AB) for rehabilitation of edentulous mandibles by assessing marginal bone levels and risk indicators for implant failure. PURPOSE To evaluate 7-year clinical outcomes and 5-year radiographic outcomes of the All-on-4 treatment concept. MATERIALS AND METHODS This retrospective case series included patients admitted for implant rehabilitations in the mandible, who were followed for 7 years clinically and 5 years radiographically. Primary outcome measures were cumulative prosthetic and implant survival using patient as the unit of analysis (Kaplan-Meier product limit estimator). Secondary outcome measure was marginal bone level (MBL) at 5 years. Variables associated with implant failure were analyzed using the Cox proportional hazards regression model to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). Binary logistic regression was used to compute odds ratio (OR) with 95% CIs for variables associated with MBL ≥2.8 mm at 5 years. RESULTS A total of 324 patients (194 women, 130 men, average age = 58.9 years) were rehabilitated with 1,296 implants supporting 324 full-arch fixed immediately loaded mandibular prostheses. Sixty-four patients (19.8%) were lost to follow-up. Prosthetic survival was 323/324 (99.7%), and 14 patients lost 18 implants, with an estimated cumulative survival rate of 95.4% at 7 years. Variables associated with implant failure were smoking (HR = 5.28; 95% CI: 1.33, 20.91]) and the learning curve effect (0.69 < HR < 0.33 for more experienced levels). Mean MBL at 5 years was 1.81 mm (95% CI: 1.70, 1.92), and smoking was associated with MBL ≥2.8 mm (OR = 2.4; 95% CI: 1.02, 5.62). CONCLUSIONS The high implant and prosthetic survival rates and excellent MBL outcome confirm the predictability and safety of the All-on-4 treatment concept over a longer term than previously reported.

Extramaxillary Surgical Technique: Clinical Outcome of 352 Patients Rehabilitated with 747 Zygomatic Implants with a Follow‐Up between 6 Months and 7 Years

BACKGROUND The use of zygomatic implants inserted in immediate function through the extramaxillary technique needs validation. PURPOSE To report the outcome of rehabilitating 352 patients with complete edentulous atrophied maxillae using 747 zygomatic implants in immediate function inserted through the extramaxillary technique. MATERIALS AND METHODS Three hundred-fifty-two consecutive edentulous patients with atrophic maxillae were rehabilitated between 2006 and 2012 with 747 zygomatic implants and 795 conventional implants. Implant and prosthetic cumulative survival and success rates were estimated through Kaplan-Meier product limit estimator. Biological and prosthetic complications were recorded after 10 days; 2, 4, and 6 months; and thereafter every 6 months. RESULTS Forty-three patients (12.2%) dropped-out, one patient lost the prosthesis (cumulative survival rate = 99.7%), and four patients lost 7 zygomatic implants, rendering an estimated cumulative survival rate of 98.2% (Kaplan-Meier). Ten patients lost 17 conventional implants (patient-specific and implant-specific cumulative survival rates of 96.7% and 97.9%, respectively). Biological complications were observed in 80 patients (22.7%) and resolved in the majority of situations, rendering an estimated cumulative success rate of 94.4% at 7 years for zygomatic implants (Kaplan-Meier). Mechanical complications occurred in 156 patients (44%), with one-third of these complications occurring in patients diagnosed with bruxism before the rehabilitation. CONCLUSIONS The rehabilitation of atrophic maxillae with zygomatic implants inserted through the extramaxillary technique in immediate function, alone or in combination with standard implants, is a viable procedure. Until the biomechanical aspects are more predictable and also because of the complexity of the surgical technique, this rehabilitation approach is not ready for every implant clinician to begin using in practice, and prior special training is recommended.

Double Full‐Arch Versus Single Full‐Arch, Four Implant‐Supported Rehabilitations: A Retrospective, 5‐Year Cohort Study

PURPOSE To report the 5-year outcome of the All-on-4 treatment concept comparing double full-arch (G1) and single-arch (G2) groups. MATERIALS AND METHODS This retrospective cohort study included 110 patients (68 women and 42 men, average age of 55.5 years) with 440 NobelSpeedy groovy implants. One hundred sixty-five full-arch, fixed, immediately loaded prostheses in both jaws were followed for 5 years. G1 consisted of 55 patients with double-arch rehabilitations occluded with implant-supported fixed prostheses, and G2 consisted of 55 patients with maxillary single-arch rehabilitations or mandibular single-arch rehabilitations occluded with natural teeth or removable prostheses. The groups were matched for age (±6 years) and gender. Primary outcome measures were cumulative prosthetic (both interim and definitive) and implant survival (Kaplan-Meier product limit estimator). Secondary outcome measures were marginal bone levels at 5 years (through periapical radiographs and using the patient as unit of analysis) and the incidence of mechanical and biological complications. Differences in survival curves (log-rank test), marginal bone level (Mann-Whitney U test), and complications (chi-square test) were compared inferentially between the two groups using the patient as unit of analysis with significance level set at p ≤ 0.05. RESULTS No dropouts occurred. Prosthetic survival was 100%. Five patients lost 5 implants (G1: n = 3; G2: n = 2) before 1 year, rendering an estimated cumulative survival rate of 95.5% (G1: 94.5%; G2: 96.4%; Kaplan-Meier, p = 0.645, nonsignificant). The average (SD) marginal bone level was 1.56 mm (0.89) at 5 years [G1: 1.45 mm (0.77); G2: 1.67 mm (0.99); p = 0.414]. The incidence rate of mechanical complications (in both interim and definitive prostheses) was 0.16 and 0.13 for G1 and G2, respectively (p = 0.032). The incidence rate of biological complications was 0.06 and 0.05 for G1 and G2, respectively (p = 0.669). CONCLUSIONS Based on the results, rehabilitating double- or single-arch edentulous patients did not yield significant differences on survival curves. The incidence of mechanical complications was significantly higher for double-arch rehabilitated patients but nevertheless, these mechanical complications did not affect the long-term survival of either the prostheses or the implants.

Single‐Tooth Rehabilitations Supported by Dental Implants Used in an Immediate‐Provisionalization Protocol: Report on Long‐Term Outcome with Retrospective Follow‐Up

BACKGROUND There is a need for long-term studies evaluating the outcome of single-tooth rehabilitations supported by dental implants in immediate loading. PURPOSE To report the long-term outcome (in excess of 5 years) of single-tooth rehabilitations supported by dental implants in an immediate-provisionalization protocol. MATERIALS AND METHODS This retrospective cohort study included 332 consecutive patients (189 females and 143 males) with an average age of 47 years (range: 16 to 82 years) who were rehabilitated between 1996 and 2006 with 594 single crowns supported by dental implants in immediate loading. Implant success rates were calculated based on implant function and using life tables. Marginal bone levels were measured at 5 and 10 years. Mechanical and biological complications were calculated for the follow-up period between implant insertion and 5 years and every 6 months thereafter. RESULTS Fifty-four patients dropped out of the study (16.5%). Nineteen patients lost a total of 25 implants (n = 23 in the maxilla; n = 2 in the mandible), rendering a cumulative survival rate of 95.7% at both 5 and 10 years of follow-up. The mean marginal bone levels were 1.56 mm (standard deviation 0.78 mm) and 1.75 mm (standard deviation 0.29 mm) at 5 and 10 years of follow-up. Mechanical complications occurred in 83 patients and 116 implants (19.5%) up to the 10-year follow-up, namely prosthetic screw loosening (2.4%), abutment complications (4.4%), fracture of provisional crowns (9.6%), and fracture of definitive ceramic crowns (3.5%). Biological complications occurred in 58 patients and 79 implants (13.3%) up to the 10-year follow-up, with the majority consisting in peri-implant pathology. CONCLUSIONS Considering the high survival rates and stable marginal bone levels after 10 years, it can be concluded within the limitations of the present study that replacement of single teeth with dental implants in an immediate-provisionalization protocol is a viable and safe treatment option for both maxilla and mandible.

Risk factors of peri-implant pathology

This study aimed to identify risk factors for the incidence of peri-implant pathology. One-thousand, two-hundred and seventy-fifty patients (255 cases and 1020 controls), rehabilitated with dental implants, were included. Peri-implant pathology was defined as the presence of peri-implant pockets ≥ 5 mm, bleeding on probing, vertical bone loss, and loss of attachment ≥ 2 mm. Cases and controls were matched for age, gender, and duration of follow-up. A logistic regression model was used, with estimation of the OR for each variable and interaction, with a level of significance of 5%. The risk factors for peri-implant pathology were: history of periodontitis (OR = 19), bacterial plaque (OR = 3.6), bleeding (OR = 2.9), bone level on the medium third of the implant (OR = 13.9), lack of prosthetic fit or non-optimal screw joint (OR = 5.9), metal-ceramic restorations (OR = 3.9), and the interaction between bacterial plaque and the proximity of other teeth or implants (PROXI) (OR = 4.3). PROXI (OR = 0.44) exerted a protective effect when independent. Based on the results, peri-implant pathology represents a group of multifactorial situations with interaction of biological and biomechanical components in its pathogenesis. It was possible to model the condition and to assess, with high precision, the risk profile of each patient.