Clinical Implant Dentistry and Related Research

Immediate‐function Brånemark System® implants (Nobel Biocare AB, Gothenburg, Sweden) have become an accepted alternative for fixed restorations in edentulous mandibles, based on documented high success rates. Continuous development is ongoing to find simple protocols for their use.

The purpose of this study was to develop and document a simple, safe, and effective surgical and prosthetic protocol for immediate function (within 2 hours) of four Brånemark System implants supporting fixed prostheses in completely edentulous mandibles: the “All‐on‐Four” concept.

This retrospective clinical study included 44 patients with 176 immediately loaded implants, placed in the anterior region, supporting fixed complete‐arch mandibular prostheses in acrylic. In addition to the immediately loaded implants, 24 of the 44 patients had 62 rescue implants not incorporated in the provisional prostheses but incorporated in final prostheses later on.

Five immediately loaded implants were lost in five patients before the 6‐month follow‐up, giving cumulative survival rates of 96.7 and 98.2% for development and routine groups, respectively. The prostheses' survival was 100%, and the average bone resorption was low.

The high cumulative implant and prostheses survival rates indicate that the “All‐on‐Four” immediate‐function concept with Brånemark System implants used in completely edentulous mandibles is a viable concept.

Based on three‐dimensional implant planning software for computed tomographic (CT) scan data, customized surgical templates and final dental prostheses could be designed to ensure high precision transfer of the implant treatment planning to the operative field and an immediate rigid splinting of the installed implants, respectively.

The aim of the present study was to (1) evaluate a concept including a treatment planning procedure based on CT scan images and a prefabricated fixed prosthetic reconstruction for immediate function in upper jaws using a flapless surgical technique and (2) validate the universality of this concept in a prospective multicenter clinical study.

Twenty‐seven consecutive patients with edentulous maxillae were included. Treatments were performed according to the Teeth‐in‐an‐Hour™ concept (Nobel Biocare AB, Göteborg, Sweden), which includes a CT scan‐derived customized surgical template for flapless surgery and a prefabricated prosthetic suprastructure.

All patients received their final prosthetic restoration immediately after implant placement, that is, both the surgery and the prosthesis insertion were completed within approximately 1 hour. In the 24 patients followed for 1 year, all prostheses and individual implants were recorded as stable.

The present prospective multicenter study indicates that the prefabrication, on the basis of models derived from three‐dimensional oral implant planning software, of both surgical templates for flapless surgery and dental pros‐theses for immediate loading is a very reliable treatment option. It is evident that the same approach could be used for staged surgery and in partial edentulism.

Immediate loading of dental implants shortens the treatment time and makes it possible to give the patient an esthetic appearance during the whole treatment period.

The aim of the present study was to evaluate an immediate‐loading treatment protocol, which included flapless surgery, implants placed in predetermined positions and connected to prefabricated provisional restorations, and the 3‐year clinical results.

A total of 97 Brånemark System® Mk IV implants (Nobel Biocare AB, Gothenburg, Sweden) with a machined surface were inserted in the maxillas of 46 patients. A presurgical three‐dimensional model of the patients' soft tissue and underlying alveolar bone anatomy was created, which allowed the clinician to place the implants in predetermined positions and connect them to prefabricated provisional restorations. A surgical template with drilling guides corresponding to each implant was used. The apical part of the master guide was equipped with a circular “mucotome,” which punched out a 5 mm hole in the mucosa to eliminate the need for flap elevation. The patients received 25 fixed partial prostheses and 27 single‐tooth restorations. Bone quality and quantity were assessed. Radiographic examinations were performed on the day of surgery/loading and at the 1‐, 2‐, and 3‐year follow‐up visits.

All implant sites showed intact buccal and lingual bone walls during surgery, confirming the accuracy of the bone‐mapping procedure. The prefabricated temporary restorations fitted, meaning that the implants were positioned clinically in the same way as on the cast. Nine implants in eight patients failed during the first 8 weeks of loading. This resulted in a cumulative survival rate of 91% after 3 years of prosthetic load. The survival rate of splinted implants was 94%. The number of failed implants was significantly higher in cases of single‐tooth replacements and placement in soft bone sites and smokers. The failed implants were successfully replaced according to a two‐stage protocol. All patients finally received the expected restoration. The marginal bone resorption was on average 1.0 mm during the first year of loading, 0.4 mm during the second year, and 0.1 mm during the third year.

The study confirmed the feasibility of an immediate‐loading treatment protocol in the maxilla, which included flapless surgery, implants and abutments placed in predetermined positions, and prefabricated provisional restorations. All failures occurred within the first 2 months of loading. The unchanged survival rate and the low average bone loss found during the following 34‐month study period indicate a good long‐term prognosis for the performed immediate‐loading treatment.

The reasons for long‐term marginal bone loss around oral implants are not well understood.

The aim of this paper is to analyze presented evidence behind anticipated reasons for long‐term marginal bone loss around oral implants.

A computerized research was conducted onPubMed inApril 2011 with the following keywords: oral implants and marginal bone resorption/crestal bone loss/bone loss/bone resorption. This search resulted in a total of one thousand one hundred ninety‐four papers of which seven hundred fifty‐three were clinical contributions. Further search and filtering finally resulted in 21 experimental studies and one hundred sixteen clinical studies, which were reviewed.

No evidence was found that primary infection caused marginal bone resorption. Clinical papers that have reported high levels of peri‐implantitis were not supported by data given. Clinical evidence was presented that the so‐called combined factors (implant hardware, clinical handling, and patient characteristics) may lead to marginal bone resorption. However, once tissue damage has been caused by combined factors, inflammation and/or infection may develop secondarily and then result in peri‐implantitis that may need particular clinical treatment.

As marginal bone loss primarily depends on numerous background factors, it seems logical that, for example, the use of poorly constructed implants placed and handled by untrained clinicians may result in high numbers of patients with secondary problems in form of peri‐implantitis; having said this, control of combined factors may likewise lead to very good clinical results where peri‐implantitis would represent a very rare disease indeed even at follow‐up times of 10 years or more.

Little is known about the long‐term outcome of implants placed in the atrophic maxilla using osteotome sinus floor elevation (OSFE) without grafting.

The study aims to evaluate the long‐term efficiency of the procedure and stability of the peri‐implant bone formed following implant placement without grafting into resorbed posterior maxilla.

Twenty‐five implants (≤10 mm in length) were placed in 17 patients using OSFE without grafting. The mean residual bone height was 5.4 ± 2.3 mm. Bone levels were evaluated at 1, 3, 5, and 10 years using periapical radiographs.

Fifteen patients (23 implants) participated in the 10‐year examination. All implants fulfilled the survival criteria. Following surgery, the implant sites gained endo‐sinus bone (mean: 3.0 ± 1.4 mm). The mean crestal bone loss (CBL) was limited to 1.0 ± 0.9 mm. The difference in mean endo‐sinus bone gain and CBL was statistically significant between 1 and 10 years, but not between 3 and 5, 3 and 10, and 5 and 10 years.

At 10 years, the implant survival rate was 100%. Endo‐sinus bone was mainly gained during the first year. This study demonstrates the long‐term predictability of OSFE without grafting and simultaneous implant placement.

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.

To evaluate 7‐year clinical outcomes and 5‐year radiographic outcomes of the All‐on‐4 treatment concept.

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.

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).

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.