Single-staged implant placement using the bone ring technique with and without membrane placement: Micro-CT analysis in a preclinical in vivo study

OBJECTIVES

To assess the impact of collagen membrane application on bone formation surrounding implants placed simultaneously with the bone ring technique.

MATERIAL AND METHODS

Dental implants were inserted simultaneously with the bone ring technique in standardized, vertical alveolar bony defects in the mandible of dogs. On one side of the mandible, the augmented sites were covered with a collagen membrane (M-Group). On the contralateral side, no membranes were used (NM-Group). Implants were left to heal with osseointegration for three and six months. The harvested samples were analyzed by means of micro-CT.

RESULTS

A nonparametric analysis of data revealed that the membranes were not a significant negative factor for bone volume (BV), but for bone-to-implant contact (BIC, p = .04). Absence of healing caps impaired BV (p = .04) and BIC (p = .02) as well. Furthermore, loss of healing caps and exposure to the oral environment significantly and negatively affected BV (p < .001) and bone mineral density (p < .05) within 2 mm below the implant shoulder. Implant exposure and healing time had a negative interaction effect on both BV (p = .01) and BIC (p = .01).

CONCLUSIONS

Within its limitations, the present study revealed no benefit of membrane application to implant placement simultaneous with the bone ring technique. Disruption of soft tissue healing was identified as a risk factor for decrease in BV and BIC.

Timing of implant placement and augmentation with bone replacement material: clinical assessment at 8 and 16 months

PURPOSE

The purpose of this study is to evaluate implants placed at different times of bone augmentation.

MATERIALS AND METHODS

Four implants were placed in seven dogs: one at a 6-month bovine mineral grafted site (6-month Bio-Oss® grafted site [6mBio]), one at a grafted membrane-protected simultaneously augmented (Fresh Bio-Oss® grafted site [FrBio]) site, one at a clotted (nongrafted clotted membrane-protected site [Clot]) membrane-protected site, and one at a pristine (nongrafted uncovered site [Cont]) site. Implants were exposed after 6 months. The same protocol was repeated on the contralateral side, at a delay of 8 months. Peri-implant care was performed throughout the hygienic phase (2 and 10 months, respectively) every 48 to 72 hours. Probing depth and bleeding on probing were recorded. Implant stability was determined by a Periotest® (Medizintechnik Gulden, Modautal, Germany). Statistical analysis was conducted using analysis of variance with repeated measures.

RESULTS

Average probing depth at the simultaneously grafted sites was 2.21 mm and 2.03 mm at 8 and 16 months, respectively. At the 6-month grafted sites, it was 1.96 mm and 1.57 mm. At the Clot sites, it was 2.68 mm and 2.07 mm, and 2.21 mm and 1.82 mm at the Cont sites, respectively. The average bleeding on probing was 0.50 and 0.42 at the FrBio sites, and 0.35 and 0.07 at the 6mBio sites during the respective periods. At the Clot sites, it was 0.50 and 0.28, and at the Cont sites, 0.43 and 0.21, respectively. Probing depth significantly reduced over the time at 6mBio, Clot, and Cont sites (p < .03). Average implant stability score at the FrBio sites was -0.24 and -0.27, and -0.50 and -0.46 at the 6mBio sites, at 8 and 16 months, respectively. At the Clot sites, it was -0.35 and -0.46. Cont sites averaged -0.37 at both periods. Implant stability was significantly higher (p < .005) comparing 6mBio over FrBio, 6mBio over Cont, and Clot over FrBio sites.

CONCLUSIONS

Immediate and delayed augmentations are safe modes. Probing depth and bleeding indices gradually improved along time. Implant stability was higher at the delayed mode.

Marginal bone-level alterations at implants installed in block versus particulate onlay bone grafts mixed with platelet-rich plasma in atrophic maxilla. a prospective 5-year follow-up study of 15 patients

BACKGROUND

Extensive atrophy of the alveolar process may require a bone-grafting procedure prior to implant treatment. Autogenous bone grafts from the iliac crest, used as onlay block and particulate bone, have been used together with sinus-lift procedure in order to rehabilitate patients with extremely resorbed maxillae. However, there are to our knowledge no 5-year follow-up studies evaluating the extent of bone-level change in patients treated with respectively block and particulate autogenous bone grafts.

PURPOSE

The purpose of this prospective clinical study was to conduct a 5-year follow-up analysis with focus on bone-level alteration in block versus particulate onlay bone grafts.

MATERIAL AND METHODS

Fifteen out of originally 19 patients who were treated with iliac bone grafts and oral implants in the maxilla have been followed through the first 5 postoperative years. In a first study conducted on 19 patients, the role of platelet-rich plasma in conjunction with autogenous bone was evaluated. In this 5-year follow-up study, the marginal bone alterations have been documented at base line, 1 year and 5 years of loading to the nearest 0,1 mm at mesial and distal surfaces of the implants. Two implants were installed on each side of the midline in either block or particulate bone grafts giving test and control sides in each patient. Additionally, two implants on each side were installed in residual bone/grafted sinus floor.

RESULT

Marginal bone alteration in the anterior maxilla appeared larger at the side augmented by block bone at baseline, and after 1 and 5 years of loading, but the change was not statistically significant. Moreover, there was a significantly higher degree of marginal alteration during the first year of loading, compared with the examinations after 5 years.

CONCLUSION

The present follow-up study showed that there is no significant difference in the extension of resorption between block- and particulate autogenous bone grafts over a 5-year period. Most of the resorption occurred during the first year in function.

Reconstruction of the severely resorbed maxilla with autogenous bone, platelet-rich plasma, and implants: 1-year results of a controlled prospective 5-year study

BACKGROUND

Prosthetic treatment of the edentulous maxilla may require bone augmentation to enable placement and integration of dental implants. This constitutes a complex healing situation, and resorption of the grafted bone and failure of the implants often occur. The application of autogenous platelet-rich plasma (PRP) has been suggested to improve incorporation and preservation of bone grafts.

PURPOSE

The aim of this controlled clinical study was to evaluate whether PRP in conjunction with grafting of particulated autogenous bone to the maxilla could improve the integration and clinical function of dental implants. An additional aim was to compare block bone grafts without PRP with PRP-treated particulated bone.

MATERIAL AND METHODS

Nineteen consecutive patients were included in the study and treated with iliac bone grafts and dental implants in the maxilla according to a split-mouth design. In the anterior maxilla, particulated bone mixed with PRP (test) was compared with onlay block grafts without additional PRP (control). In the posterior maxilla, particulated bone grafts with (test) or without (control) PRP were placed as sinus inlay grafts. After 6 months of healing, 152 implants (8 implants/patient) (TiOblast, Astra Tech AB, Mölndal, Sweden) were placed. Test (PRP; 76 implants) and non-PRP (76 implants) sides were evaluated and compared by implant survival rate, marginal bone level, and implant stability using resonance frequency analysis (RFA) during 1 year in function.

RESULTS

Two control implants in control sites in two patients were lost at abutment connection. After 1 year in function, no further implants were lost, giving an overall survival rate of 98.7%. The marginal bone level measurements showed no significant differences, although there was a tendency toward less resorption on PRP sides. RFA measurements showed statistically significantly higher implant stability quotient values for PRP sites at abutment connection in the anterior but not in the posterior regions.

CONCLUSIONS

The present clinical study showed that a high implant survival rate and stable marginal bone conditions can be achieved after 1 year of loading in the maxilla following autogenous bone grafting whether or not PRP is used. RFA measurements revealed differences at abutment connection, which could be explained by the type of graft rather than as an effect of PRP. Although no obvious positive effects of PRP on bone graft healing could be demonstrated, the handling of the particulated bone grafts was improved.

Implant design and intraosseous stability of immediately placed implants: a human cadaver study

OBJECTIVE

The objective of this study was to explore effects of implant macrodesign and diameter on initial intraosseous stability and interface mechanical properties of immediately placed implants.

MATERIAL AND METHOD

Mandibular premolars of four fresh-frozen human cadavers were extracted. Ø 4.1/4.8 mm ITI TE, Ø 4.1 and 4.8 mm solid screw synOcta ITI implants were placed into freshly prepared extraction sockets. Resonance frequency analysis was conducted to quantify primary implant stability quotient (ISQ). Installation torque value (ITV) and removal torque value (RTV) of the implants were measured using a custom-made strain-gauged torque wrench connected to a data acquisition system at a sample rate of 10,000 Hz. The vertical defect depth around the collar of each implant was measured directly by an endodontic spreader. The bone-implant contact was determined in digitalized images of periapical radiographs and expressed as percentage bone contact.

RESULTS

The ISQ values of the TE implant was higher than the Ø 4.1 mm implant (P<0.01), and comparable with the Ø 4.8 mm implants (P>0.05). ITVs and RTVs of TE and Ø 4.8 mm implants were higher than the Ø 4.1 mm implant, although the differences between groups were statistically insignificant (P>0.05). The vertical defect depths around all types of implants were similar. In the radiographic analyses, percentage bone-implant contact of the TE and Ø 4.8 mm implants were comparable at the marginal bone region and both were higher than that of the Ø 4.1 mm ITI implant. Nonparametric correlations between groups revealed a significant correlation between ITV and RTV (r=0.838; P<0.001), but not between ISQ values and ITVs and RTVs (P>0.05).

CONCLUSION

Immediately placed ITI TE implant leads to initial intraosseous stability and interface mechanical properties comparable with a wide diameter implant.

Monitoring of implant stability in grafted bone using resonance frequency analysis. A clinical study from implant placement to 6 months of loading

The aim of this prospective study was to compare implants placed in grafted and normal non-grafted maxilla by means of resonance frequency analysis (RFA), clinical stability and implant failure. Twenty-nine patients with severe atrophy of the edentulous maxilla were treated with autogenous bone grafts as onlay (24 patients) or as interpositional grafts in conjunction with a Le Fort I osteotomy (five patients) 6 months prior to placement of 222 implants. Ten non-grafted patients treated with 75 Brånemark implants in the edentulous maxillae served as a control group. RFA was performed at implant placement, abutment connection and after 6 months of bridge loading. Seventeen (8%) implants were lost in the grafted bone and one (1%) in normal bone. RFA revealed a similar pattern in both grafted and normal maxillae, i.e. increasing resonance frequency (RF) with time (Wilcoxon Signed Rank test for paired data). Twenty implants that were rotation mobile (low primary stability) at the time of insertion showed a significantly lower value at implant placement according to RFA (Mann-Whitney U-test, P = 0.020). The RF for the failed implants revealed a tendency towards lower values (Mann-Whitney U-test, P = 0.072), compared to the successful implants. It is concluded that implants placed in grafted bone when using a two-stage technique achieve a stability similar to that of implants placed in normal non-grafted bone.

Implant stability measurement of delayed and immediately loaded implants during healing.. A clinical resonance-frequency analysis study with sandblasted-and-etched ITI implants

The purpose of the present study was (1) to measure the primary stability of ITI implants placed in both jaws and determine the factors that affect the implant stability quotient (ISQ) determined by the resonance frequency method and (2) to monitor implant stability during the first 3 months of healing and evaluate any difference between immediately loaded (IL) implants and standard delayed loaded (DL) implants. The IL and DL groups consisted of 18 patients/63 implants and 18 patients/43 implants. IL implants were loaded after 2 days; DL implants were left to heal according to the one-stage procedure. The ISQ was recorded with an Osstell apparatus (Integration Diagnostics AB, Gothenburg, Sweden) at implant placement, after 1, 2, 4, 6, 8, 10 and 12 weeks. Primary stability was affected by the jaw and the bone type. The ISQ was higher in the mandible (59.8+/-6.7) than the maxilla (55.0+/-6.8). The ISQ was significantly higher in type I bone (62.8+/-7.2) than in type III bone (56.0+/-7.8). The implant position, implant length, implant diameter and implant deepening (esthetic plus implants) did not affect primary stability. After 3 months, the gain in stability was higher in the mandible than in the maxilla. The influence of bone type was leveled off and bone quality did not affect implant stability. The resonance-frequency analysis method did not reveal any difference in implant stability between the IL and DL implants over the healing period. Implant stability remained constant or increased slightly during the first 4-6 weeks and then increased more markedly. One DL and IL implant failed; both were 8 mm long placed in type III bone. At the 1-year control, the survival rate of the IL and the DL implants was 98.4% and 97.7%, respectively. This study showed no difference in implant stability between the IL and DL procedures over the first 3 months. IL short-span bridges placed in the posterior region and full arch rehabilitation of the maxilla with ITI sandblasted-and-etched implants were highly predictable.

Factors influencing the dynamic behaviour of human teeth

Modal analysis is carried out to test the natural frequencies of certain human teeth, including central incisors (CIs), canines (CAs), first premolars (FPs) and first molars (FMs). A total number of 1007 teeth are tested, taking into account tooth type, oral location, age and gender, to analyse the effects of the above-mentioned factors on the natural frequency of the sample teeth. The results reveal that no significant difference in the natural frequency is noted among teeth in the four different intra-oral quadrants. Nevertheless, tooth type and age elicit an effect upon the value of the natural frequency of teeth. On the other hand, the mean value for the natural frequency of CIs (1.27 +/- 0.15 kHz), CAs (1.30 +/- 0.15 kHz), FPs (1.27 +/- 0.15 kHz) and FMs (1.16 +/- 0.12 kHz) for males are significantly lower (p < 0.01) than the analogous figure for females (1.41 +/- 0.21 kHz for CIs, 1.40 +/- 0.18 kHz for CAs, 1.37 +/- 0.20 kHz for FPs, and 1.25 +/- 0.16 kHz for FMs). Moreover, the natural frequency of teeth in male subjects varies with age (p < 0.05). The highest mean frequency of CIs, CAs and FPs for the male subjects is found for the group aged between 40 and 49 years. On the other hand, the natural frequency for the similar set of teeth for the female subjects is shown to be in no way associated with age.

Implant Stability Measurements Using Resonance Frequency Analysis in the Grafted Maxilla: A Cross-Sectional Pilot Study

BACKGROUND

High failure rates have been presented for implants placed in grafted bone. The bone graft-implant interface constitutes a most complex healing situation, where the time scale for osseointegration and development of implant stability currently is not known.

PURPOSE

The aim of the study was to measure the stability of implants placed in grafted bone after various follow-up periods.

METHODS

Implant stability measurements by means of resonance frequency analysis were performed in 10 patients previously treated with a Le Fort I osteotomy and interpositional bone grafts. The implants were placed 3 to 4 months after the grafting procedure. Sixty-seven Brånemark implants were subjected to resonance frequency analysis measurements at fixture placement and up to 5.5 years after implant surgery. Periapical radiographs were used for assessment of marginal bone levels.

RESULTS

The radiographic examinations showed marginal bone loss with time during the 5.5-year follow-up. The resonance frequencies varied from 5860 to 8440 Hz. When accounting for abutment length and marginal bone level, there was a tendency of increasing resonance frequency with time. Two implants with low resonance frequencies failed during the prosthetic phase.

CONCLUSION

The results indicate an increased implant stability with time, which may reflect bone formation, remodeling, and maturation at the implant interface.