Temperature changes at the implant-bone interface during simulated surface decontamination with an Er:YAG laser

PURPOSE: This study investigated temperature changes at the implant-bone interface during simulated implant surface decontamination with an Er:YAG laser. MATERIALS AND METHODS: Stepped cylinder implants with three different surfaces (titanium plasma sprayed, sandblasted and acid etched, and hydroxyapatite coated) were placed in bone blocks cut from freshly resected pig femurs. An artificial periimplant bone defect with a size of 6 mm2 provided access for laser irradiation in the coronal third of the implant. A 540-pm periimplantitis application tip was used at a distance of 0.5 mm from the implant surface. Pulse energy was varied between 60 and 120 mJ at 10 pps. The bone block was placed into a 37 degrees C water bath to simulate in vivo thermal conductivity and diffusitivity of heat. K-type thermocouples connected to a digital meter were used to register temperature changes at three levels of the periimplant bone. RESULTS: The temperature at the implant-bone interface did not exceed 47 degrees C after 120 seconds of continuing laser irradiation. Temperature elevations were significantly higher at the hydroxyapatite-coated implants than in the two titanium surface groups (P < .001). CONCLUSION: Decontamination of implant surfaces by means of the Er:YAG laser did not excessively heat the periimplant bone within the energy range investigated. This technique therefore seems clinically safe, at least when used with the surfaces studied.     

Erbium,Chromium:Yttrium‐Scandium‐Gallium‐Garnet Laser Effectively Ablates Single‐Species Biofilms on Titanium Disks Without Detectable Surface Damage

Background: Increasing evidence implicates biofilms, consisting of species such as Porphyromonas gingivalis (Pg), in the etiology of peri‐implantitis. Multiple approaches to ablate biofilms on failing implants have been proposed and include use of lasers, most recently the erbium, chromium:yttrium‐scandium‐gallium‐garnet (Er,Cr:YSGG) laser. The purpose of this study is to establish an in vitro single‐species biofilm model on implant surfaces and determine power settings of the Er,Cr:YSGG laser that remove biofilm without causing physical damage to disks. Methods: Single‐species biofilms consisting of Pg strain 381 were grown on titanium disks, including: 1) sandblasted, large‐grit, acid‐etched (SLA); 2) calcium phosphate nano‐coated (CaP); 3) anodized; or 4) machined surfaces. Power settings from 0 to 1.5 W using an Er,Cr:YSGG laser equipped with radial firing tip were used. Biofilm formation/removal was quantitated using confocal and scanning electron microscopy. Surface changes in temperature, microroughness, and water contact angle were analyzed. Results: Results show confluent Pg biofilm coating all disk surfaces. The laser removed biofilms from all surfaces, with CaP and SLA surfaces requiring power setting of 1.0 to 1.5 W for ablation of bacteria coating the disks. Within this power range, and with water spray, there were no changes in surface temperature, surface roughness, or contact angle on any surfaces tested. Conclusion: The Er,Cr:YSGG laser with radial firing tip and water spray was able to effectively ablate ≥95% of biofilm on all types of tested titanium surfaces, using clinically relevant power settings, without causing measurable physical changes to surfaces.     

Adhesion pattern and growth of primary human osteoblastic cells on five commercially available titanium surfaces

Objective: The aim of this study is to analyze the morphology and proliferation of human osteoblastic cells in vitro on five commercially available titanium surfaces. Materials and methods: Human primary cells of the osteoblastic lineage were obtained from bone explants. The cells were plated on polished (T1), machined (T2), sand‐blasted/acid‐etched (T3), sand‐blasted/acid‐etched, modified with hydrogen peroxide rinse (T4), and plasma‐sprayed titanium (T5) disks. Cell morphology was studied after 6, 24, 72 h, 7 and 14 days of culture by scanning electron microscopy. The formation and distribution of focal adhesions was investigated by immunocytochemical staining at 3, 6 and 24 h. Cell growth was measured by an MTT assay after 3, 7 and 9 days of culture. Moreover, the production of osteocalcin and osteoprotegerin (OPG) was evaluated in the supernatants by ELISA. Results: Morphological analysis revealed that substrate topography profoundly affected cells' shape and their anchoring structures. Large lamellipodia were formed on polished and machined surfaces, while thin filopodia were more frequently observed on T3 and T4 samples. Moreover, cells formed stronger focal adhesions on T3 and T4 surfaces, and cell proliferation was higher on rough surfaces. Osteocalcin production was higher on the T4 surface, whereas OPG steadily increased on every surface. Conclusions: Taken together, these data show that all the surfaces allowed cell attachment, adhesion and proliferation, but T4 and T5 surfaces appeared to be a better substrate for the adhesion, proliferation and differentiation of cells of the osteoblastic lineage. To cite this article:
Passeri G, Cacchioli A, Ravanetti F, Galli C, Elezi E, Macaluso GM. Adhesion pattern and growth of primary human osteoblastic cells on five commercially available titanium surfaces.
Clin. Oral Impl. Res. 21 , 2010; 756–765.
doi: 10.1111/j.1600‐0501.2009.01906.x     

Osteoblast attachment on titanium disks after laser irradiation

PURPOSE: Osteoblast attachment on titanium surfaces is necessary to achieve new bone formation and osseointegration. The purpose of this study was to examine osteoblast attachment on irradiated titanium disks. MATERIALS AND METHODS: Machined, hydroxyapatite (HA)-coated, sandblasted, and titanium plasma-sprayed (TPS) surfaces were irradiated with either a carbon dioxide (CO2) or an Er,Cr:YSGG laser. A control group of nonirradiated disks was also examined. Osteoblast cultures were cultivated on the titanium disks and examined with scanning electron microscopy. RESULTS: The findings demonstrated that osteoblasts could be grown on all of the surfaces. Pseudopodia and a spread of cells that demonstrated maturation were observed on the lased irradiated titanium disks. CONCLUSIONS: The data show that laser irradiation of titanium surfaces may promote osteoblast attachment and further bone formation.     

Surface chemistry effects of topographic modification of titanium dental implant surfaces: 1. Surface analysis

PURPOSE: To analyze the surface composition of 34 different commercially available titanium dental implants. MATERIALS AND METHODS: Surface composition was evaluated by x-ray photoelectron spectroscopy (XPS). Samples were divided into 4 groups, depending on their surface topography (machined, sandblasted, acid etched, or plasma sprayed). RESULTS: Statistical analysis of the data showed a clear relationship between surface composition and topography, which can be easily accounted for by the chemical effects of the surface treatment performed. On average, acid-etched and plasma-sprayed surfaces had higher titanium and lower carbon concentration than machined surfaces. DISCUSSION AND CONCLUSION: Current studies aimed at the evaluation of implants with different topography should not implicitly assume that topography is the only variable controlling the biologic response. Rather, when comparing different topographies, it should be taken into account that surface chemistry may be a variable as well.     

Effects of an Erbium:Yttrium‐Aluminum‐Garnet Laser and Ultrasonic Scaler on Titanium Dioxide‐Coated Titanium Surfaces Contaminated With Subgingival Plaque: An In Vitro Study to Assess Post‐Treatment Biocompatibility With Osteogenic Cells

Background: Effects of conventional ultrasonic scaler versus an erbium:yttrium‐aluminum‐garnet (Er:YAG) laser on titanium surfaces contaminated with subgingival plaque from patients with peri‐implantitis are evaluated in terms of: 1) plaque and biocorroded titanium oxide coating removal; 2) surface change induction; and 3) residual biocompatibility toward osteoblasts. Methods: Subgingival plaque‐coated titanium disks with a moderately rough surface were fixed with ethanol and treated with an ultrasonic scaler (metal tip) or Er:YAG laser (20.3 or 38.2 J/cm²) in non‐contact mode. Fluorescent detection of residual plaque was performed. Disk surface morphology was evaluated by scanning electron microscopy. Viability, attachment, proliferation, and differentiation of Saos‐2 osteoblasts on new and treated disks were assayed by propidium iodide/DNA stain assay and confocal microscopic analysis of cytoskeleton, Ki67, expression of osteopontin and alkaline phosphatase, and formation of mineralized nodules. Results: Both methods resulted in effective debridement of treated surfaces, the plaque area being reduced to 11.7% with the ultrasonic scaler and ≤0.03% with the Er:YAG laser (38.2 J/cm²). Ultrasound‐treated disks showed marked surface changes, incomplete removal of the titanium dioxide (TiO₂) layer, and scanty plaque aggregates, whereas the Er:YAG laser (38.2 J/cm²) completely stripped away the plaque and TiO₂ layer, leaving a micropitted surface. Both treatments maintained a good biocompatibility of surfaces to Saos‐2 osteoblasts. Air‐water cooling kept disk temperature below the critical threshold of 47°C. Conclusion: This study shows that an ultrasonic scaler with metal tip is less efficient than high‐energy Er:YAG irradiation to remove the plaque and TiO₂ layer on anodized disks, although both procedures appear capable of restoring an adequate osseoconductivity of treated surfaces.     

Bone healing around titanium and titanium nitride-coated dental implants with three surfaces: an experimental study in rats

Background: Titanium nitride (TiN) has been used in many fields as a coating of surgical instruments, with the purpose of creating materials more resistant to wear and corrosion and also reducing adhesion. Purpose: The aim of this study was to evaluate the biocompatibility of TiN‐coated dental implants. Materials and Methods: Forty‐five rats were used in this study. One hundred eighty 2 mm 2 mm implants (P.H.I., San Vittore Olona, Milano, Italy) were used. The implants were divided into the following three groups: Group 1 (n= 60):30 machined and 30 machined coated with TiN Group 2(n= 60):30 sandblasted and 30 sandblasted coated with TiN Group 3 (n= 60):30 titanium plasma sprayed, 30 titanium plasma sprayed and coated with TiN Four implants were placed in each rat, two implants coated with TiN on the right tibia and two uncoated implants on the left. The animals were killed after 5, 10, 20, 30, or 60 days. Another 18 implants were used for surface roughness analysis. Results: The present study showed that the healing around the TiN‐coated implants was similar to that observed around the uncoated surfaces. Conclusions: TiN coating demonstrated a good biocompatibility, did not have untoward effects on the periimplant bone formation, and did not change the surface roughness values.     

Bactericidal effect of the Er:YAG laser on dental implant surfaces: an in vitro study

BACKGROUND: The aim of the in vitro study was to examine the bactericidal effect of an Er:YAG laser on common dental implant surfaces. METHODS: Seventy-two titanium platelets with 3 different surfaces--sandblasted and acid-etched (SA), titanium plasma-sprayed (TPS), and hydroxyapatite-coated (HA)--were incubated with a suspension of Streptococcus sanguinis (ATCC 10556). Irradiation at pulse energies of 60 and 120 mJ and a frequency of 10 pps was performed on a computer-controlled XY translation stage. After laser treatment the specimens were sonicated and the bacterial growth examined by counting colony forming units on blood agar plates. Temperature elevations during irradiation were investigated using K-type thermocouples. Laser treated implant surfaces were analyzed by means of electron microscopy. RESULTS: Compared to non-irradiated specimens, mean bacterial reductions of 99.51% (SA), 98.39% (HA), and 99.6% (TPS) at a pulse energy of 60 mJ and 99.92% (SA), 99.85% (HA), and 99.94% (TPS) at 120 mJ were calculated. At these laser parameters, no excessive temperature elevations or morphological implant surface alterations were detected. CONCLUSIONS: Even at low energy densities, the Er:YAG laser has a high bactericidal potential on common implant surfaces. Clinical studies are justified to evaluate the applicability and efficacy of the Er:YAG laser in the treatment of peri-implantitis.     

Acute inflammatory response to laser-induced micro- and nano-sized titanium surface features

Background: The inflammatory process induced by implant surfaces is an important component of the tissue response, where limited knowledge is available regarding the role of surface topography. With laser ablation, a combined micro‐ and nanoscale surfacemodification could be created, which have been shown to enhance bone growth and biomechanical stability in vivo. Purpose: The aim of this article was to evaluate the early in vivo inflammatory response to laser‐modified titanium disks, with machined titanium disks and sham operation sites serving as controls. Materials and Methods: Circular disks were installed in a subcutaneous rat model for 24 and 72 hours, where the cell number, cell types, and cytokine levels were evaluated. Results: The results revealed that significantly fewer inflammatory cells (mononuclear and polymorphonuclear) were attracted to the sites with the laser‐modified implants compared with the machined titanium implants. Similar concentrations of pro‐inflammatory cytokines (TNF‐a and MCP‐1), together with slightly higher cell viability, were observed around the laser‐modified surface compared with the machined surface. Conclusions: The results in the present study suggest that the combination of surface micro and nano features of the laser‐treated surface contributes to the downregulation of early inflammatory events.     

Early cell response of osteogenic cells on differently modified implant surfaces: Sequences of cell proliferation,adherence and differentiation

Objectives

Osseointegration of dental implants is a crucial prerequisite for long-term survival. Therefore, surface modifications are needed to interact with the extracellular environment and to trigger osteogenic cell responses such as cell proliferation, adherence, and differentiation. The purpose of this study was to investigate different surface modifications in vitro over 2 weeks.

Effect of enamel preparation method on in vitro marginal microleakage of a flowable composite used as pit and fissure sealant

OBJECTIVES: The aim of this in vitro study was to evaluate the microleakage in occlusal surfaces, after preparation with Er:YAG laser and compared to the diamond-bur conventional technique. METHODS: Thirty premolars were divided into three groups: I - high-speed handpiece + 37% phosphoric acid; II - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + 37% phosphoric acid; and III - Er:YAG laser (350 mJ, 4 Hz and 112 J/cm(2)) + Er:YAG laser (80 mJ, 4 Hz, and 25 mJ/cm(2)). All cavities received the same adhesive system and were restored with flowable composite according to manufacturer's instructions. Teeth were submitted to thermal cycling and immersed in 50% silver nitrate solutions for 8 h in total darkness. Specimens were sectioned longitudinally in the bucco-lingual direction, in slices of 1 mm thick. Each slice was immersed into photo developing solution and was photographed, and microleakage was scored from 0 to 7, by three calibrated examiners. RESULTS: A statistically significant difference (P < 0.0001) was observed between Er:YAG laser prepared and etched specimens and those in the other groups. CONCLUSIONS: It can be concluded that no significant difference was noted between the two types of enamel preparation when etching was performed. Preparing and treating the enamel surface exclusively by Er:YAG laser resulted in the highest degree of leakage.     

Effects of diode and Nd:YAG laser irradiation on titanium discs: a scanning electron microscope examination

BACKGROUND: Dental lasers have been recommended for uncovering submerged implants as well as decontaminating implant surfaces when treating peri-implantitis. The aim of this study was to show the possible alterations in titanium disc surfaces using an Nd:YAG or a diode laser. METHODS: Three different titanium discs were used (sandblasted, titanium plasma-sprayed [TPS], and hydroxyapatite [HA] coated) to determine the effects of laser irradiation on these surfaces using a scanning electron microscope (SEM). The discs were either irradiated with a pulsed Nd:YAG laser with a contact handpiece and power settings of 2.0, 4.0, and 6.0 W or with a diode laser at 5.0, 10.0, and 15.0 W power settings and continuous wave (cw) in the contact handpiece. Irradiated areas were compared with control titanium sites which were not lased. The specimens were prepared for SEM examination after the disc irradiation. RESULTS: The SEM examination demonstrated extensive melting in all of the Nd:YAG laser irradiated areas. Damage was seen in all TPS- and HA-coated discs even at the lowest power setting. Loss of porosity, coating microfractures, and a relatively smooth surface were observed. In contrast, the diode laser did not cause any damage or modify the disc surface. Regardless of the power setting, there was no visible difference between lased and non-lased surfaces after cw irradiation with the diode laser. CONCLUSIONS: From these findings, it was concluded that the diode laser (980 nm) does not damage titanium surfaces, which should be of value when uncovering submerged implants and treating peri-implantitis.     

Osteoblast response to titanium surfaces functionalized with extracellular matrix peptide biomimetics

Objective: Functionalizing surfaces with specific peptides may aid osteointegration of orthopedic implants by favoring attachment of osteoprogenitor cells and promoting osteoblastic differentiation. This study addressed the hypothesis that implant surfaces functionalized with peptides targeting multiple ligands will enhance osteoblast attachment and/or differentiation. To test this hypothesis, we used titanium (Ti) surfaces coated with poly‐l ‐lysine‐grafted polyethylene glycol (PLL‐g‐PEG) and functionalized with two peptides found in extracellular matrix proteins, arginine–glycine–aspartic acid (RGD) and lysine–arginine–serine–arginine (KRSR), which have been shown to increase osteoblast attachment. KSSR, which does not promote osteoblast attachment, was used as a control. Materials and methods: Sandblasted acid‐etched titanium surfaces were coated with PLL‐g‐PEG functionalized with varying combinations of RGD and KRSR, as well as KSSR. Effects of these surfaces on osteoblasts were assessed by measuring cell number, alkaline phosphatase‐specific activity, and levels of osteocalcin, transforming growth factor beta‐1 (TGF‐β1), and PGE₂. Results: RGD increased cell number, but decreased markers for osteoblast differentiation. KRSR alone had no effect on cell number, but decreased levels of TGF‐β1 and PGE₂. KRSR and RGD/KRSR coatings inhibited osteoblast differentiation vs. PLL‐g‐PEG. KSSR decreased cell number and increased osteoblast differentiation, indicated by increased levels of osteocalcin and PGE₂. Conclusions: The RGD and KRSR functionalized surfaces supported attachment but did not enhance osteoblast differentiation, whereas KSSR increased differentiation. RGD decreased this effect, suggesting that multifunctional peptide surfaces can be designed that improve peri‐implant healing by optimizing attachment and proliferation as well as differentiation of osteoblasts, but peptide combination, dose and presentation are critical variables. To cite this article:
Bell BF, Schuler M, Tosatti S, Textor M, Schwartz Z, Boyan BD. Osteoblast response to titanium surfaces functionalized with extracellular matrix peptide biomimetics.
Clin. Oral Impl. Res. 22 , 2011; 865–872.
doi: 10.1111/j.1600‐0501.2010.02074.x     

Comparison of marginal microleakage of flowable composite restorations in primary molars prepared by high-speed carbide bur, Er:YAG laser, and air abrasion

PURPOSE: The purpose of this study was to assess in vitro the influence of 3 cavity preparation devices (carbide bur, Er:YAG laser, and air abrasion) on the microleakage of flowable composite restorations in primary teeth. METHODS: Fifteen primary second molars were selected, and Class V cavities were prepared on the buccal/lingual surfaces, being assigned to 3 groups (n= 10). Group 1 (control) was prepared using a high-speed handpiece and was acid etched. Group 2 was prepared and treated with a Er:YAG laser (400mJ/4Hz and 80mJ/4Hz, respectively) and was acid etched. Group 3 was prepared and treated with an air abrasion system and was acid etched. Cavities were restored and stored for 7 days. Restorations were polished, thermocycled, immersed in 0.2% rhodamine B, sectioned, and analyzed for leakage. RESULTS: Er:YAG laser-prepared cavities showed the highest degree of infiltration. The performance of the air abrasion device was comparable to that of the high-speed handpiece. CONCLUSION: It may be concluded that the method of cavity preparation affected the microleakage of Class V cavities restored with flowable composite in primary teeth.     

Effect of pulse duration of Er: YAG laser on dentin ablation

The present study examined the effects on dentin ablation efficiency arising from various pulse durations of Er: YAG laser at a fixed energy fluence. Ten flat human dentin disks were prepared and exposed to an Er: YAG laser at 1 pps for three seconds at pulse durations of 100-500 microsec with 150 mJ/pulse (40.0 J/cm x pulse). The depth and diameter of the ablated dentin were measured and the ablation volume was estimated. Irradiated surfaces and cross-sections were observed using a SEM. Depth of the removed dentin increased and the diameter of the spot decreased without a change in the estimated volume at increased pulse durations. SEM observation of the irradiated surfaces revealed that there were no morphological differences when the pulse duration was changed. When the specimens were cross-sectioned, the ablated dentin had a dome shape and there was a dark layer under the irradiated surface.     

Effect of chemically modified titanium surfaces on protein adsorption and osteoblast precursor cell behavior

PURPOSE: To investigate the effects of different chemically modified titanium surfaces on protein adsorption and the osteoblastic differentiation of human embryonic palatal mesenchymal (HEPM) cells. MATERIALS AND METHODS: Three different surfaces were evaluated. The first, a machined surface (Ti-M), was considered a control. The second surface was acid etched (Ti-AE). The third surface was prepared by exposing the Ti-AE samples to sodium hydroxide (NaOH) solution (Ti-AAE). The surface characteristics of chemically modified titanium were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and profilometry. To evaluate the production of biomarkers, commercial kits were utilized. RESULTS: Surface composition and morphology affected the kinetics of protein adsorption. Ti-AE surfaces manifested a greater affinity for fibronectin adsorption compared to Ti-M or Ti-AAE surfaces. It was observed that Ti-AE and Ti-AAE surfaces promoted significantly greater cell attachment compared to Ti-M surfaces. Statistically significant differences were also observed in the expression of alkaline phosphatase (ALP) activity, osteocalcin, and osteopontin on all 3 titanium surfaces. ALP activity and osteocalcin production up to day 12 suggested that differentiation of the cells into osteoblasts had occurred and that cells were expressing a bone-forming phenotype. CONCLUSIONS: It was thus concluded from this study that surface morphology and composition play a critical role in enhancing HEPM cell proliferation and differentiation into osteoblast cells.     

Scanning electron microscopic analysis of diseased and healthy dental hard tissues after Er:YAG laser irradiation: in vitro study

The aim of this study was to treat carious lesions, sound dentin, and enamel either with conventional methods or with an Er:YAG laser and to compare the results. Thirty freshly extracted carious human teeth were divided into two groups. In the first group, lesions were treated with burs in a dental handpiece; in the second group, we used the Er:YAG laser with parameters recommended by the manufacturer (Kavo). After treatment, the teeth were prepared for scanning electron microscopic observation. On laser-treated teeth, scaly, flaky, rough surfaces were seen: surfaces were clean with several morphological reliefs that may enhance bonding resin restoration. The Er:YAG laser beam can ablate carious dentin with an energy level of 250 mJ at 2 Hz. Sound dentin can be cut at 300 mJ and 2 Hz; for enamel, 350 mJ and 3 Hz are required. The Er:YAG laser seems to be effective in the treatment of carious lesions and in cavity preparation in vitro.