Heat generated during seating of dental implant fixtures

LIMITED EVIDENCE SUGGESTS NO CORRELATION BETWEEN IMPLANT INSERTION TORQUE AND IMPLANT SURVIVAL AND MARGINAL BONE LOSS

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Clinical effect of the high insertion torque on dental implants: A systematic review and meta-analysis. Lemos CA, Verri FR, de Oliveira Neto OB, Cruz RS, Gomes JML, da Silva Casado BG, Pellizzer EP. J Prosthet Dent 2021; 126(4): 490-496.

SOURCE OF FUNDING

Not reported.

TYPE OF STUDY/DESIGN

Systematic review with meta-analysis (SR).

Rationale for Mini Dental Implant Treatment

Mini dental implants can be used to support crowns and partial and complete dentures in compromised edentulous sites. Lack of bone width or site length may be treated with mini implants. Mini implants have less percutaneous exposure and displacement that may reduce complications. Nonetheless, mini implants transmit about twice the load to the supporting bone, and thus, control of occlusal loading is important. In fixed prosthetics, rounded flat cusps, splinting, implant protective occlusal schemes, and placement only in dense bone sites are features of successful mini implant treatment. With removable prosthetics, multiple mini implants may be needed for appropriate retention and load resistance. Maxillary lateral incisor and mandibular incisor sites may be best suited for mini implant treatment. However, past research on dental implants has been directed at standard sized implants. While mini implants are indeed dental implants, they behave somewhat differently under functional load, and the clinician should be circumspect and very judicious in their use. This article is a mini review and not a systematic review. The topics covered are not pervasive because each would require a monograph or textbook for a complete discussion.

Surgical Drill Bit Design and Thermomechanical Damage in Bone Drilling: A Review

As drilling generates substantial bone thermomechanical damage due to inappropriate cutting tool selection, researchers have proposed various approaches to mitigate this problem. Among these, improving the drill bit design is one of the most feasible and economical solutions. The theory and applications in drill design have been progressing, and research has been published in various fields. However, pieces of information on drill design are dispersed, and no comprehensive review paper focusing on this topic. Systemizing this information is crucial and, therefore, the impetus of this review. Here, we review not only the state-of-the-art in drill bit designs-advances in surgical drill bit design-but also the influences of each drill bit geometries on bone damage. Also, this work provides future directions for this topic and guidelines for designing an improved surgical drill bit. The information in this paper would be useful as a one-stop document for clinicians, engineers, and researchers who require information related to the tool design in bone drilling surgery.

Effects of heat conduction of implant surface at thermal stimulation on implant placement

The purpose of this study is to investigate, in vitro, how two different implant placement methods (one and two-stage implant placement) affect implant surface temperature after thermal stimulation. Two titanium screw implants were used and three thermocouples were attached to the implant surface at 0.5 mm (ch1), 5.5 mm (ch2) and 9.0 mm (ch3) under each platform. Experimental devices were fabricated pouring polymerization resin under a condition that imitated the two embedded technique with the one-stage implant placement model (1-stage) and the two-stage implant placement model (2-stage). A hot water storage device was installed in each model and hot water at three temperatures (60 °C, 70 °C and 100 °C) was flowed. The temperature change over time at the implant surface by the thermocouple was recorded. From the measurement data, the maximum temperature (Max-temp) at the implant surface, the time to reach 47 °C (47 °C r-time), and the duration of 47 °C or more (47 °C c-time) were calculated, and the test was repeated 26 times using the same method. The mean of repeated measurements was determined and statistical analysis was performed. Max-temp showed significant differences between each implant placement method, each channel and each thermal stimulation (p < 0.01). In this study suggested that the implant surface could reach 47 °C with 60 °C thermal stimulation in a 1-stage. In addition, it rose over 47 °C at 70 °C. The 2-stage implant surface did not rise to 47 °C.

Heat Generation at the Implant-Bone Interface by Insertion of Ceramic and Titanium Implants

PURPOSE

The aim of this study is to record material- and surface-dependent heat dissipation during the process of inserting implants into native animal bone.

MATERIALS AND METHODS

Implants made of titanium and zirconium that were identical in macrodesign were inserted under controlled conditions into a bovine rib tempered to 37 °C. The resulting surface temperature was measured on two bone windows by an infrared camera. The results of the six experimental groups, ceramic machined (1), sandblasted (2), and sandblasted and acid-etched surfaces (3) versus titanium implants with the corresponding surfaces (4, 5, and 6) were statistically tested.

RESULTS

The average temperature increase, 3 mm subcrestally at ceramic implants, differed with high statistical significance (p = 7.163 × 10^-9, resulting from group-adjusted linear mixed-effects model) from titanium. The surface texture of ceramic implants shows a statistical difference between group 3 (15.44 ± 3.63 °C) and group 1 (19.94 ± 3.28 °C) or group 2 (19.39 ± 5.73 °C) surfaces. Within the titanium implants, the temperature changes were similar for all surfaces.

CONCLUSION

Within the limits of an in vitro study, the high temperature rises at ceramic versus titanium implants should be limited by a very slow insertion velocity.

Intraosseous Temperature Change during Installation of Dental Implants with Two Different Surfaces and Different Drilling Protocols: An In Vivo Study in Sheep

Background: The intraosseous temperature during implant installation has never been evaluated in an in vivo controlled setup. The aims were to investigate the influence of a drilling protocol and implant surface on the intraosseous temperature during implant installation, to evaluate the influence of temperature increase on osseointegration and to calculate the heat distribution in cortical bone. Methods: Forty Brånemark implants were installed into the metatarsal bone of Finnish Dorset crossbred sheep according to two different drilling protocols (undersized/non-undersized) and two surfaces (moderately rough/turned). The intraosseous temperature was recorded, and Finite Element Model (FEM) was generated to understand the thermal behavior. Non-decalcified histology was carried out after five weeks of healing. The following osseointegration parameters were calculated: Bone-to-implant contact (BIC), Bone Area Fraction Occupancy (BAFO), and Bone Area Fraction Occupancy up to 1.5 mm (BA1.5). A multiple regression model was used to identify the influencing variables on the histomorphometric parameters. Results: The temperature was affected by the drilling protocol, while no influence was demonstrated by the implant surface. BIC was positively influenced by the undersized drilling protocol and rough surface, BAFO was negatively influenced by the temperature rise, and BA1.5 was negatively influenced by the undersized drilling protocol. FEM showed that the temperature at the implant interface might exceed the limit for bone necrosis. Conclusion: The intraosseous temperature is greatly increased by an undersized drilling protocol but not from the implant surface. The temperature increase negatively affects the bone healing in the proximity of the implant. The undersized drilling protocol for Brånemark implant systems increases the amount of bone at the interface, but it negatively impacts the bone far from the implant.

Healing at sites prepared using different drilling protocols. An experimental study in the tibiae of sheep

The aim of the experiment was to study the healing at implants installed in site prepared in bone type 1 using different rotation speeds and cooling strategies. The tibiae of twelve sheep were used as experimental sites. Two implant sites were prepared in each tibia using drills either at a high or a mixed speed under irrigation. At the mixed-speed sites, 60 rpm without irrigation were applied for the last drill, the countersink and during implant installation. Biopsies representing the healing after 1, 2, and 6 weeks were obtained and ground sections were prepared. At the histological analyses, after 1 week of healing, no new bone was found at both high- and mixed-speed sites. After 2 weeks of healing, small amounts of newly formed bone were observed in the cortical layer, reaching percentages of 3.6±3.0% at the mixed-speed sites, and of 2.2±1.5% at the high-speed sites. An irrelevant quantity of new bone was seen in the marrow compartments of a few specimens. After 6 weeks of healing, new bone was found in higher quantity, reaching in the cortical compartment 66.9±6.8% and 67.3±17.7% at the mixed- and high-speed sites, respectively. The respective percentages in the marrow compartment were 23.2±13.0% and 30.6±29.2%. No statistically significant differences between high- and mixed-speed groups were found. It was concluded that the use of the last drill and the installation of the implant with or without irrigation yielded similar bone healing and osseointegration.

An ectodermal dysplasia patient treated with a small diameter implant supporting a single crown

Ectodermal dysplasia (EDD) is a developmental disorder that affects the skin, hair, and teeth among other organs generated in the ectoderm. Dental implants have been used to successfully treat partial edentulism in EDD patients, but the success rate is much lower for these patients. The report herein is a successful case of a single mini, small diameter, implant used to support a single crown of a mandibular right second premolar. A review of implant treatment in EDD patients is included.

Mini Implants Supporting Fixed Partial Dentures in the Posterior Mandible: A Retrospective

Small-diameter, or mini, dental implants have been successfully used to support removable and fixed oral prostheses. These implants impart about twice the per-square-millimeter force on the supporting bone and this should be addressed during treatment planning. In the posterior jaws, bite forces are of a higher magnitude than in the anterior jaws and may induce an overload of the supporting bone and failure of the osseointegration. Thus there should not be occlusal contact in functional excursions that induce off axial loads. The cases presented herein demonstrate that mini dental implants may be used successfully to support fixed partial dentures in mandibular sites in highly selected patients. Attention should be given to the bone density of the site, very slow seating rotation of the implant with intermissions or cooling during insertion, observation of a 4-month healing time, flapless placement, treatment of any existing periodontitis, an insoluble cement, and exclusion of occlusal contact in functional excursions. Importantly, a narrow, rounded occlusal table should be used to minimize off axial loads and an insoluble luting cement should be used to prevent loosening of the crowns due to dissolution of the cement and an overload of the retained implant with any residual cement-retained in the retainer. The implant that supports the cement retained retainer will be subjected to leveraged rotation that may destroy the osseointegration and result in exfoliation of the implant.