Antonio Liñares

Influence on early osseointegration of dental implants installed with two different drilling protocols: a histomorphometric study in rabbit.

OBJECTIVE to evaluate early osseointegration of dental implants installed with two different drilling protocols. MATERIAL AND METHODS thirty-six cylindrical shape Mozo Grau implants, with a diameter of 3.75 and 11 mm long, were placed into the distal condyle (submerged) of each femur of 18 New Zealand rabbits. In the control group, a 3.3 mm diameter drill was used as the last one prior implant installation (standard protocol). In the test group, the same procedure was carried out but an additional 3.5 mm drill was used as the final one (oversized protocol) Thus, we could obtain different primary stability at day 0 between groups. Sacrifice of the animals was after 2, 4 and 8 weeks. Histomorphometric analysis (bone-to-implant contact ratio [BIC%]) and implant stability quotient (ISQ) values (Ostell ) were registered at each sacrifice time. RESULTS the ISQ values were statistically significant different between groups at day 0 (control: 69.65; test: 64.81); and after 2 weeks (control: 77.93; test: 74). However, after 4 and 8 weeks the results were similar. BIC% showed a similar tendency, with 58.69% for the control group and 40.94% for the test group after 2 weeks, this difference being statistically significant. At 4- and 8-week interval, BIC% was similar. CONCLUSION at 2-week interval (early healing), osseointegration had been influenced by different primary stability at implant installation, being slower in the oversized protocol (lower primary stability), which could be especially risky in challenging clinical situations, such as soft bone (class 3 and 4) and early/immediate loading. However, from 4 week on, these differences disappeared. Nevertheless, we have to consider that a direct transfer of the results of this animal study (time bone repair mechanisms) into clinic has to be done with caution.

Effect of immediate or delayed loading following immediate placement of implants with a modified surface.

OBJECTIVE to evaluate the effect of the timing of loading on bone-to-implant contact (BIC) following immediate placement of implants with a hydrophilic sandblasted, large-grit and acid-etched surface (modSLA) into fresh extraction sockets in a minipig model. MATERIAL AND METHODS six minipigs were used in this study. In each hemi-mandible, two conical shape implants (TE, Straumann implants) with a hydrophilic surface (modSLA) were placed in fresh extraction sockets. In one side of the mandible (control), two implants were immediately placed in fresh extraction sockets. The implants were loaded after 4 weeks of healing. At the contralateral side (test), two implants were immediately placed and loaded. After 8 weeks of healing, the animals were sacrificed and histologically analysed. RESULTS during the experimental period, no implants were lost and all of them presented to be osseointegrated. The percentage of BIC was similar in both groups: 66.1% and 65.1% for the control and test group, respectively. Furthermore, the distance from the shoulder of the implant to bone crest and the distance from the shoulder to the first BIC were similar in both groups. CONCLUSION immediate implant placement and loading showed similar BIC with immediate placement and delayed loading when implants with a modSLA surface were used. Both procedures showed similar buccal bone crest levels, which presented some resorption irrespective of the treatment modality.

Ridge alterations following flapless immediate implant placement with or without immediate loading. Part II: a histometric study in the Beagle dog

OBJECTIVE To assess the effect of immediate loading on ridge alterations following implants placed into fresh extraction sockets in a dog model. MATERIAL AND METHODS Six Beagle dogs were used. Four implants were placed into post-extraction sockets in the lower jaw immediately after the removal of premolars 3 and 4. In the control side, two implants remained without occlusal loading, and in the test side, they received an immediate prosthesis with occlusal contacts (involving implant sites). Extraction sockets without implants were used as a test in non-involved implant sites. Three months later, the dogs were sacrificed. RESULTS Vertical distance from implant shoulder to bone crest (BC) was similar for both groups. BC at the buccal aspect was located 3.66 mm apical to the shoulder in the test group and 4.11 mm in the control group. This difference was not statistically significant. Buccal bone resorption was more pronounced in the premolar 3 area than in the premolar 4 area. In edentulous sites, the buccal bone crest was located 0.97 mm apical to the lingual counterpart. CONCLUSION Immediate implant placement with or without immediate loading does not prevent the amount of bone resorption that occurs following tooth extraction without immediate implant placement.

Soft tissue dimensions in flapless immediate implants with and without immediate loading: an experimental study in the beagle dog

OBJECTIVE The aim of the present study was to evaluate the peri-implant soft tissue dimensions in flapless immediate implants with and without immediate loading. MATERIAL AND METHODS This study was carried out on six beagle dogs. Four implants were placed (two per side) immediately after tooth extraction (third and fourth premolars). Flapless immediate implant placement was performed in one hemimandible (control). The same procedure was performed in the contralateral side and immediate prosthesis was connected (test). After 3 months of healing, the dogs were sacrificed. RESULTS None of the implants and prosthesis were lost. Barrier epithelium in the loaded group was 2.51 mm at the buccal and 2.34 mm at the lingual aspect. In the no loaded group, the results were similar, 2.54 and 2.2 mm at the buccal and lingual side, respectively. Connective tissue in the loaded group was 1.38 mm at the buccal and 0.65 mm at the lingual aspect, and in the no loaded group 1.48 mm at the buccal and 0.53 mm at the lingual side. Biological width dimensions were 3.9 mm at the buccal and 2.95 mm at the lingual aspect for the loaded group, and 4.01 and 2.64 mm at the buccal and lingual aspect for the no loaded group. CONCLUSIONS The results of the present study suggested that soft tissues dimensions around immediate implants with immediate loading were similar to immediate implants without loading.

Flapless immediate implant placement with or without immediate loading: a histomorphometric study in beagle dog.

OBJECTIVE To assess the osseointegration process after flapless immediate implant placement with or without immediate loading. MATERIAL AND METHODS This study was carried out on six beagle dogs. Four implants were placed in the lower jaw (two per side) in each dog immediately after tooth extraction (3rd and 4th premolars). Flapless immediate implant placement was performed in one hemimandible (control). The same procedure was carried out in the contra-lateral side and immediate prosthesis was connected with occlusal contacts (test). After 3 months of healing, the dogs were sacrificed for histomorphometric analysis. RESULTS Twelve implants were placed in each group. None of the implants and prosthesis was lost. The percentage of bone-to-implant contact (BIC %) was similar in both groups: 82.72% (test) and 76.96% (control). Differences were found neither in the inter-thread bone area (test: 83.45%, control: 80.65%) nor in peri-implant bone area (test: 94.37%, control: 94.81%). CONCLUSION In this animal model where the implants were well within the confines of the extraction socket, osseointegration following flapless immediate implant placement and loading can be achieved in the same manner as immediate placement without loading.

Vertical and horizontal ridge alterations after tooth extraction in the dog: flap vs. flapless surgery

OBJECTIVE To compare ridge alterations after flap and flapless tooth extraction in the vertical and horizontal dimension in the dog model. MATERIAL AND METHODS This study was carried out on five Beagle dogs. Four extractions were performed in the lower jaw of each dog (two per side. Pm3, Pm4). At the time of tooth extraction, flap surgery was performed on one side (control group). On the contra-lateral side, a flapless extraction was performed (test group). Mesial sockets were left untreated on both sides. After 3 months of healing, the dogs were sacrificed and prepared for histological analysis. RESULTS Ten samples were evaluated on each group. The vertical difference in height between the buccal and lingual crest was 1.48 mm for the flap, and 1.22 mm for the flapless group. The horizontal dimension of the ridge was 4.41 mm (at 1 mm from the crest), 5.72 mm (at 3 mm from the crest) and 6.67 mm (at 5 mm form the crest) in the flap group. In the flapless group, the measurements were 4.5, 5.58 mm and 6.44 at 1, 3 and 5 mm from the crest, respectively. CONCLUSION Evaluating ridge alterations in the vertical and horizontal dimension after 3 months of healing following tooth extraction, results for the flap and the flapless group were very similar.

Influence of Abutment Height on Maintenance of Peri-implant Crestal Bone at Bone-Level Implants: A 3-Year Follow-up Study

In this 3-year follow-up study, peri-implant bone loss at bone-level implants was evaluated with two definitive abutment heights: 1 mm and 2.5 mm. Peri-implant bone loss was defined as the distance between the implant shoulder and the first bone-to-implant contact from the time of loading to the 36-month follow-up, estimated using periapical radiographs. The bone loss was increased at the time of follow-up, to 1.30 mm (95% confidence interval [CI]: 0.70-1.89 mm; SD = 1.89) and 0.33 mm (95% CI: 0.11-0.55; SD = 0.59) at 36 months in short and long abutments, respectively. Placement of short abutments induced higher peri-implant bone loss at bone-level implants during a peri-implant recall program.

Impact of immediate loading on early soft tissue healing at two‐piece implants placed in fresh extraction sockets: an experimental study in the beagle dog

OBJECTIVES To study early soft tissue healing of immediately placed implants with or without immediate loading in the dog. MATERIAL AND METHODS Forty-eight implants were placed in the distal sockets of Pm3 and Pm4 in the lower jaw of 12 beagle dogs immediately after tooth extraction. In the control group, no loading was applied. In the test group, an immediate loading restoration with occlusal contacts was performed. Dogs were sacrificed at 2, 4, and 8 weeks for histological analysis. RESULTS At the end of the study, there was a 100% implant and prosthesis survival. The biological width dimension was similar in both groups at all the studied healing periods. This dimension tended to decrease from week 2 to 8 in both groups, on both the buccal and lingual side. The barrier epithelium tended to stop at the implant-abutment interface in both groups and also decreased in length from week 2 to 8, on the buccal and the lingual side. Soft tissue recession remained low and occurred mainly in the test group. CONCLUSIONS The characteristics, dimension, and healing pattern of the peri-implant soft tissues were similar around immediate implants with or without immediate loading.