Sequential morphometric evaluation at UnicCa ® and DCD ® implant surfaces. An experimental study in the dog

Application of the break-even point to express the bone dynamics around implants

PURPOSE

The aim of this study was to apply the break-even point concept to express the dynamics of bone formation and resorption around implants.

METHODS

Published data on new bone and parent bone densities around implants from one human and three dog studies were selected and used for analysis. The break-even point (BEP) of the bone density (BD) was assessed. The BEP is the point at which, in a graph, the lines representing the formation of new bone and resorption of old bone intersect. BEP is expressed in time (x; days) of occurrence and percentage of bone (y; %) at which the break-even point occurs and illustrates the grade of bone modeling. The sooner the occurrence, the faster the bone formation in relation to the resorption of the old bone.

RESULTS

In the marrow and cortical compartments, BEP of bone density occurred after 7.9 days (BD% 24.5%) and >30 days, respectively. Different surfaces presented similar BEP, ranging between 9.7 and 11.2 days (BD% 19.1-22.5%). BEP at implants installed in the human maxilla occurred after 29-30.4 days (BD% 28.3-29.6%).

CONCLUSION

The present study showed that the parameters used to express the break-even point can provide information on the influence of the model used, surface characteristics, and bone quality on bone modeling/remodeling around implants.

Healing at implants installed in osteotomies prepared either with a piezoelectric device or drills: an experimental study in dogs

OBJECTIVE

To compare osseointegration and marginal bone level at implants placed in osteotomies prepared with either conventional drills or a piezoelectric device.

MATERIAL AND METHODS

Three months after the extraction of all mandibular premolars and first molars, two recipient sites were selected. The osteotomies were randomly prepared with either conventional drills (drill sites) or a piezoelectric device (piezoelectric sites). Implants were installed and a submerged healing was allowed. The animals were euthanized in groups of six after 4 and 8 weeks of healing. Biopsies were obtained for histological preparation. Coronal level of osseointegration (bone level) and bone-to-implant contact percentage (BIC%) were evaluated.

RESULTS

After 4 weeks of healing, the bone level was 0.6 ± 0.9 mm for the piezoelectric sites and 1.6 ± 0.7 mm for the drill sites (p = 0.173). After 8 weeks, the respective measures were 0.9 ± 0.3 mm and 1.0 ± 1.1 mm (p = 0.917). After 4 weeks of healing, a new bone apposed onto the implant surface was found at fractions of 54.9 ± 6.7% and 55.1 ± 16.6% for the piezoelectric and the drill sites, respectively (p = 0.674). The respective total bone fractions, including new and old bone, was 64.0 ± 4.8% and 63.4 ± 20.4% (p = 0.917). After 8 weeks, a new bone increased to 67.4 ± 6.7% and 62.9 ± 12.5% for the piezoelectric and the drill sites, respectively (p = 0.463). The respective total bone fractions were 70.4 ± 5.5% and 67.8 ± 12.1% (p = 0.753).

CONCLUSIONS

The use of a piezoelectric device for implant site preparation is a safe procedure that allows a proper integration since the early periods of healing similar to that observed using conventional drills.

Influence of the position of the antrostomy in sinus floor elevation on the healing of mini-implants: a randomized clinical trial

AIM

To evaluate histologically the healing of mini-implants installed after sinus floor elevation using a lateral approach and placing the antrostomy at different level from the sinus floor.

MATERIAL AND METHODS

Sinus floor elevation using a lateral approach was performed in 24 healthy volunteers. The antrostomy was randomly placed either close to the base of the sinus floor (group base) or at about 3-4 mm cranially to it (group standard). After 6 months of healing, mini-implants were installed within the grafted region, through the alveolar crest. Three months later, biopsies were collected.

RESULTS

Sixteen biopsies from 16 patients were available for histological analyses. The new bone reached fractions of 40.9 ± 11.9% and 48.5 ± 20.1% at the base and standard groups, respectively (p = 0.208). Xenograft particles were found in contact with the implant surface at percentages of 12.1 ± 11.0% in the base group, and 15.9 ± 23.7% in the standard group (p = 0.674).

CONCLUSIONS

Based on the present study, the choice of one or the other position of antrostomy did not influence significantly the outcome and, therefore, should be left to the preference of the surgeon.

Effect of Plasma of Argon Treated Implants on Bone Density: A Randomized, Controlled, Histomorphometric Study in Dogs

Background:

Altering surface characteristics by increasing its energy and hydrophilicity will accelerate the interaction between cells and implant surface. Energy and hydrophilicity tend to disappear over a short time. The implant surface may be reactivated by the use of argon plasma

Objective:

To assess bone density at cleaned and activated titanium implants using argon plasma.

Methods:

Mandibular premolars and first molars were extracted bilaterally in eight Beagle dogs. After three months, four implants, two treated with argon plasma (test; plasma) and two left without treatment (control), were randomly installed in one side of the mandible. Abutments were applied on the implants and a non-submerged healing was allowed. After one month, the same surgical procedures were adopted on the opposite side of the mandible. The animals were euthanized after one month and ground sections representing the healing after 1 and 2 months were obtained for histological examination.

Results:

No statistically significant differences were found between test and control sites (p < 0.05). After 1 month of healing, new bone was 32.5 ± 12.2% and 33.8 ± 8.8% at the plasma and control sites, respectively. After 2 months, the respective values were 50.8 ± 21.5% and 47.6 ± 15.6%.

Conclusion:

The treatment of the implant surface with argon plasma did not have a significant effect on bone density around implants.

Unravelling the effect of macro and microscopic design of dental implants on osseointegration: a randomised clinical study in minipigs

Several dental implants are commercially available and new prototype design are constantly being fabricated. Nevertheless, it is still unclear what parameters of the design affect most the osseointegration of dental implants. The purpose of this study is to assess the effects of the microscopic and macroscopic design of dental implants in the osseointegration by comparing three macroscopic designs (Straumann tissue level (STD), essential cone (ECD) and prototype design (PD)) and six surface treatments. A total of 96 implants were placed in 12 minipigs. The implant stability quotient (ISQ), was assessed at the time of implantation, as well as at 2, 4 and 8 weeks. Histomorphometric and statistical analyses were conducted at the different sacrifice times, being 2, 4 and 8 weeks, to analyse the bone to implant contact (BIC), the bone area density (BAT) and the density of bone outside the thread region (ROI). The macroscopic design results showed higher ISQ values for the ECD, whereas the histomorphometric analysis showed higher ossoeintegration values for the STD. Regarding the microscopic design, both Sandblasted plus acid etching (hydrochloric/sulphuric acid) in a nitrogen atmosphere (SLActive) and Shot-blasted or bombarded with alumina particles and posterior alkaline immersion and thermal treatment (ContacTi) showed superior results in terms of osseointegration and reduced the osseointegration times from 8 weeks to 4 weeks compared to the other analysed surfaces. In conclusion, each of the macroscopic and microscopic designs need to be taken into account when designing novel dental implants to enhance the osseointegration process.

Effectiveness of a new dental implant bioactive surface: histological and histomorphometric comparative study in minipigs

OBJECTIVES

The objective of this study was to assess, by histomorphometric analysis, the degree of bone apposition on two types of dental implant's surfaces: a novel implant that combines Al₂O₃ abrasive particle blasting with thermochemical treatment (ContacTi), compared to a standard surface treatment obtained by sandblasting and acid etching (shot blasting).

MATERIALS AND METHODS

Twelve minipigs were used, placing the studied implants in the maxillae, and divided into three groups according to the time of sacrifice: 2, 4, and 8 weeks after implant placement. Histological and histomorphometric analyses were performed following standardized tissue polymerization, cutting, and staining and examined under optical and high-resolution electron microscope.

RESULTS

For all measurements, the novel surface presented higher levels of osseointegration as compared to the shot blasting surface. Bone to implant contact (BIC) in the maxillae for ContacTi presented values of 49.02, 83.20, and 85.58% at 2, 4, and 8 weeks, respectively, significantly higher compared to the shot blasting surface values of 39.32, 46.53, and 46.20% for the same time points. Bone area density (BAD) presented values of 26.52, 61.21, and 59.50% for ContacTi surface implants and 22.95, 36.26, and 49.50% for the shot blasted surface implants. Signs of osteoconductivity were observed in the ContacTi surfaces at 2 weeks.

CONCLUSIONS

The ContacTi surface achieved a faster growth of hard tissues around the implants, when compared to the shot blasting surface, and for all evaluated histomorphometric parameters, the values were higher at all measured time points.

CLINICAL RELEVANCE

ContacTi could be a new surface improving the osseointegration in oral implantology.