Tommie Van de Velde

A Prospective Study on the Accuracy of Mucosally Supported Stereolithographic Surgical Guides in Fully Edentulous Maxillae

BACKGROUND Flapless implant placement using guided surgery is widespread, although clinical publications on the precision are lacking. PURPOSE The purpose of this study was to evaluate the accuracy of mucosal-supported stereolithographic guides in the edentulous maxillae. MATERIALS AND METHODS Seventy-eight OsseoSpeed™ implants (Astra Tech AB, Mölndal, Sweden) of 3.5 to 5 mm width and 8 to 15 mm length were installed consecutively in 13 patients. Implants were functionally loaded on the day of surgery, and implant location was assessed with a computed tomography scan. Mimics 9.0 software (Materialise N.V., Leuven, Belgium) was used to fuse the images of the virtually planned and actually placed implants, and the locations, axes, and interimplant distances were compared. RESULTS One implant was lost shortly after insertion because of abscess formation caused by remnants of impression material. Seventy-seven implant locations were analyzed. The deviation at the entrance point ranged between 0.29 mm and 2.45 mm (SD: 0.44 mm), with a mean of 0.91 mm. Average angle deviation was 2.60° (range 0.16-8.86°; SD: 1.61°). At the apical point, the deviation ranged between 0.32 mm and 3.01 mm, with a mean of 1.13 mm (SD: 0.52 mm). The mean deviation of the coronal and apical interimplant distance was respectively 0.18 mm (range 0.07-0.32 mm; SD: 0.15) and 0.33 mm (range 0.12-0.69 mm; SD: 0.28). These deviations are lower than the global coronal and apical deviations. CONCLUSION The present study is the first to investigate the accuracy of stereolithographic, full, mucosally supported surgical guides in the treatment of fully edentulous maxillae. Clinicians should be warned that angular and linear deviations are to be expected. Short implants show significantly lower apical deviations compared with longer ones. Reasons for implant deviations are multifactorial; however, it is unlikely that the production process of the guide has a major impact on the total accuracy of a mucosal-supported stereolithographic guide.

Clinical Outcome and Bone Preservation of Single TiUnite™ Implants Installed with Flapless or Flap Surgery

BACKGROUND Flapless, free-handed implant surgery offers advantages for patient comfort, but studies on long-term clinical success based on marginal bone loss are scarce. AIM The aim of this study was to compare single implants installed with a flap (F) or flapless (FL) surgery with respect to survival and marginal bone preservation after at least 3 years. MATERIALS AND METHODS Fifty-three TiUnite™ Brånemark implants, installed in 49 patients (27 females; 22 males; mean age 53 years) were examined. Then, 25 F and 28 FL were delayed loaded; bone level from the abutment-implant level was measured on intraoral radiographs. From 44 (21 F, 23 FL), 31 (18F, 13 FL), and 36 (18 F, 18 FL) implants, radiographs were available at baseline and after 1 and 3 years of function. RESULTS The overall survival rate was 100% and the overall mean bone loss after an average of 38 months was 1.35 mm (SD 0.91; range 0-3.7). Both F and FL showed increasing bone loss during the first year with a higher bone loss for FL than for F sites (p < .01). Afterward, no further bone loss occurred and both groups were statistically equal (p > .7). On individual implant level, nearly 80% in both F and FL were considered a success showing bone loss between 1.5 and 1.9 mm. CONCLUSIONS Single implants yield an excellent prognosis with stable bone levels irrespective of the surgical technique, and free-handed flapless surgery is a viable alternative to more extensively planned guided surgery. Proper case selection and clinical experience are considered prerequisites for a predictable treatment outcome.

Effect of Implant Design on Preservation of Marginal Bone in the Mandible

BACKGROUND Implant design and surface may have an influence on the marginal bone response during immediate functional loading. AIM The purpose of this study was to radiographically study the effect of implant design on marginal bone preservation at immediately loaded implants used for prosthetic rehabilitation of the completely edentulous mandible. MATERIALS AND METHODS A total of 39 patients, previously treated with five implants for support of a full-arch fixed bridge in the mandible, were included in the study. Either machined Brånemark implants (Ma) (Nobel Biocare AB, Gothenburg, Sweden) or surface modified Astra Tech implants with (Mi) or without a microthreaded neck (Ti) (TiOblast, AstraTech AB, Mölndal, Sweden) were used. All fixtures were loaded with a provisional glass fiber or metal-reinforced screw-retained restoration within 24 hours. The provisional restorations were replaced by a 12-unit screw-retained metal-ceramic or metal-resin cantilever bridge after 3 months. Bone loss from baseline to 1 year of loading was measured by means of intraoral radiographs. Only patients with baseline and 1-year radiographs of all implants were selected for comparison. Statistical analysis was carried out on both patient and implant levels. RESULTS The survival rates after 1 year in function were 98.6, 100, and 100% for the Ma, Ti, and Mi implants, respectively. The overall mean bone loss after 1 year was 1.03 mm (SD 0.87; range -0.77 to 2.5). The mean bone loss was calculated to 1.52 (SD 0.66) for the Ma group, 0.79 (SD 0.79) for the Ti group, and 0.70 (SD 1.01) for the Mi group. There was a significant difference between Ma and Ti (p = .023) and between Ma and Mi (p = .046) groups but not within Ti and Mi implants (p = .70). These conclusions were also valid when the statistical analysis was performed on implant level. CONCLUSIONS There is no impact of design and surface on implant survival in the completely edentulous mandible. Bone preservation in immediately loaded implants in the mandible is influenced by implant design and significantly better on surface-modified AstraTech implants compared with machined Brånemark implants. In the mandible, a microthread design of the implant collar does not seem to improve bone preservation.

Succesfactoren voor implantatie

Het gebruik van tandheelkundige implantaten is de laatste jaren in vrijwel alle indicatiesmogelijk gewordenmet een steeds gunstiger prognose. Dit komtmet name door een aantalmodificaties in zowel implantaat, chirurgie als prothetiek en door een betere kennis van de biologischemechanismen