OsseoSpeed™ is the implant with a chemically modified surface and a unique nanoscale topography. The OsseoSpeed implant has clearly improved results compared to earlier generations of implants. The following summaries of the pre-clinical and clinical scientific articles reveal the mechanisms behind the performance and clinical outcome.
Immediate functional loading of implants in single tooth replacement: a prospective clinical multicenter study
Single-tooth implants have been variously reported to show high success rates both when benefitting from a delayed period of healing for osseointegration and when immediately temporized but without immediate functional loading. Only few studies have presented data on immediate functional loading of single-tooth implants (STI).
In conjunction with immediate loading of implants there has been data presented on the benefits of using an osteotome technique for lateral bone condensation to increase peri-implant bone density and the bone-to-implant contact thereby increasing primary implant stability.
Purpose: This immediate load study aimed to compare the use of an ostetome and drilling protocol for the placement of STIs (Astra Tech 4.0 mm and 4.5 mm 0) in a prospective randomized controlled manner.
Materials and Methods: Seventy male and 81 female patients with good general health were enrolled to the study. Smokers represented 23% of the study population with 11% smoking > 10 cigarettes per day. These patients were evenly distributed amongst the groups. All patients had one tooth missing for at least 3 months, with healthy adjacent teeth. A minimum criterion of 20 Ncm was required as an insertion torque and no indication for grafting was allowed. Patients were randomly allocated to one of three groups. Group 1 acted as control (n = 57) where implants were inserted using a standard drilling protocol according to manufacturer's recommendations, submerged for undisturbed healing, and exposed after 3 months for restoration and functional loading. In group 2 (n = 50) patients also benefitted from the same standard drilling protocol but implants were placed into immediate functional load while in group 3 (n = 54) osteotomy preparation was via a modified technique using first a 2.5 mm diameter drill followed by osteotomes of increasing diameter to widen the preparation, with implants placed into immediate functional load.
In order to fulfill the requirement of immediate functional loading for groups 2 and 3, an impression pick-up of the implant was made at the time of surgery and a customized abutment and temporary acrylic crown fabricated within 24 hours. Definitive abutments were tightened to 20 Ncm and the temporary crown cemented with Temp Bond. Crowns were placed into centric occlusal contact. After 3 months the implants in the control group 1 were exposed and restored with customized abutments and temporary acrylic crowns. After a further 3 months of functional loading all implants were subject to new impressions and definitive ceramometal crowns were delivered.
Patients were recalled at 3 and 12 months for assessment of plaque, probing depth and mucositis scores as well as measurement of the width of keratinized tissue and the papilla length on the mesial and distal of each implant-retained crown.
Standardized intra-oral radiographs taken with a paralleling technique were evaluated by an experienced, blinded radiologist at baseline (insertion) and at 3 and 12 months follow-up to assess the level of the marginal bone relative to the implant-abutment junction. Comparisons between groups were analyzed statistically.
Results: Three implants in group 3 failed to osseointe-grate (5.5%), while one implant in group 2 failed to integrate (2%). Periodontal parameters were comparable between the groups except for probing depth of 4-5 mm on the distal aspect of group 1 implants which was significantly higher than for groups 2 and 3, p < 0.05.
When comparing radiographs there was a notable difference between group 3 and the other two groups with less marginal bone loss, although this did not reach significance. However when considering the frequency of implants which lost > 1.0 mm there was a significant difference between groups 2 and 3 compared to the control group 1, p = 0.01. Additionally there was a significant difference in the outcome for 4.0 mm 0 implants compared to 4.5 mm 0, in favor of the former which showed less bone loss, p < 0.05. When considering treatment protocol and implant diameter as covariables the analysis revealed a highly significant difference for increased bone loss at 4.5 mm 0 implants placed using a conventional surgical protocol, p < 0.01. Other variables such as sex and smoking status had no influence, while location was influential, p = 0.04.
Discussion and Conclusion: Until now no data appears to be available using both an osteotome technique and immediate functional loading for single tooth implants. The data in the current study is broadly comparable with that of other studies, in that the outcome measures from clinical and radiographic parameters are similar to that achieved with a conventional protocol. In the current study implants lost the majority of bone between baseline and 3 months with little additional bone loss thereafter. This too is in agreement with previous studies. The finding that more bone loss was observed at 4.5 mm 0 implants is not currently explained, although one can postulate about the influence of primary stability issues and implant geometry, however the marginal bone levels recorded at the 4.5 mm 0 implants are similar to those recorded by Cooper and Norton for early and immediate restoration protocols.
The higher failure rate of implants subject to immediate loading is of concern, in particular for 5.5% in group 3 where an osteotome technique was used. It has been proposed that this technique results in trabecular fractures which do not occur when using a drilling protocol. This may require further consideration.
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