Biological performance of a novel bovine hydroxyapatite in a guided bone regeneration model: A preclinical study in a mandibular defect in dogs.

OBJECTIVES: This preclinical model study aims to evaluate the performance and safety of a novel hydroxyapatite biomaterial (Wishbone Hydroxyapatite, WHA) on guided bone regeneration compared to a commercially available deproteinized bovine bone mineral (Bio-Oss, BO). MATERIAL AND METHODS: Twenty-four beagle dogs were allocated to three timepoint cohorts (4, 12, and 26 weeks) of eight animals each. In all animals, four critical-sized, independent wall mandibular defects were created (32 defects/cohort). Each animal received all four treatments, allocated randomly to separated defects: WHA + collagen membrane (M), BO + M, no treatment (Sham, Sh), and Sh + M. At each timepoint, the specimens were harvested for histologic and histomorphometric analyses to determine the newly formed bone and osteoconductivity. RESULTS: At 4 weeks, bone regeneration was significantly higher for WHA + M (46.8%) when compared to BO + M (21.4%), Sh (15.1%), and Sh + M (23.1%) (p < 0.05); at 12 and 26 weeks, regeneration was similar for WHA and BO. Bone-to-material contact increased over time similarly for WHA + M and BO + M. From a safety point of view, inflammation attributed to WHA + M or BO + M was minimal; necrosis or fatty infiltrate was absent. CONCLUSIONS: WHA + M resulted in higher bone regeneration rate than BO + M at 4 weeks. Both BO + M and WHA + M were more efficient than both Sh groups at all timepoints. Safety and biocompatibility of WHA was favorable and comparable to that of BO.

The Effects of Direct Polymethyl Methacrylate and Zirconia-on-Ti-Base Abutments on Peri-implant Soft Tissue Integration: A Study in Minipigs.

PURPOSE: To assess two types of abutment materials routinely used in daily practice-direct polymethyl methacrylate (PMMA) and a zirconia-on-Ti-base abutment-and their effects on peri-implant soft tissues and bone remodeling in a minipig model. MATERIALS AND METHODS: A total of 40 implants were placed in five minipigs in a single-stage surgery. Four different types of abutment materials (n = 10 per group) were used: (1) titanium (control); (2) zirconia (control); (3) PMMA (test 1); and (4) Ti-base (zirconia bonded to a titanium framework; test 2). After 3 months of healing, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attachment) were assessed on each abutment mesially and distally, and the distance from the implant margin to the first bone-to-implant contact (BIC) was measured. RESULTS: No statistically significant differences were found among the four groups regarding soft tissue dimensions (P = .21), and a long junctional epithelium (mean: 4.1 mm) and a short connective tissue attachment (mean: 0.3 mm) were found in the majority of abutments. In some samples, the junctional epithelium extended all the way to the bone level. The measured peri-implant bone remodeling was similar in all four groups (P = .25). CONCLUSIONS: The present findings indicate that both direct PMMA and zirconia-on-Ti-base abutments seem to allow soft tissue integration similar to that of titanium and zirconia abutments. However, clinical studies are warranted to either confirm or refute the observed findings and to further investigate the influence of different materials on mucointegration.

The effects of direct polymethylmethacrylate and zirconia-on-Ti-base abutments on peri-implant soft tissue integration: A study in minipigs.

PURPOSE: To assess two types of abutment materials routinely used in daily prac-tice-direct polymethyl methacrylate (PMMA) and a zirconia-on-Ti-base abut-ment-and their effects on peri-implant soft tissues and bone remodeling in a mini-pig model. MATERIALS AND METHODS: A total of 40 implants were placed in five mini-pigs in a single-stage surgery. Four different types of abutment materials (n = 10 per group) were used: (1) titanium (control); (2) zirconia (control); (3) PMMA (test 1); and (4) Ti-base (zirconia bonded to a titanium framework; test 2). After 3 months of healing, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attach-ment) were assessed on each abutment mesially and distally, and the distance from the implant margin to the first bone-to-implant contact (BIC) was measured. RESULTS: No statistically significant differences were found among the four groups regarding soft tissue dimensions (P = .21), and a long junctional epithelium (mean: 4.1 mm) and a short connective tissue attachment (mean: 0.3 mm) were found in the majority of abutments. In some samples, the junctional epithelium extended all the way to the bone level. The measured peri-implant bone remodeling was similar in all four groups (P = .25). CONCLUSION: The present findings indicate that both di-rect PMMA and zirconia-on-Ti-base abutments seem to allow soft tissue integration similar to that of titanium and zirconia abutments. However, clinical studies are war-ranted to either confirm or refute the observed findings and to further investigate the influence of different materials on mucointegration.

Effects of Minocycline Hydrochloride as an Adjuvant Therapy for a Guided Bone Augmentation Procedure in The Rat Calvarium.

This in vivo study reports the influence of minocycline-HCl administration on extra-skeletal bone generation in a Guided Bone Augmentation model, utilizing titanium caps placed on the intact as well as perforated calvaria of rats. The test group was administered 0.5 mg/mL minocycline-HCl with the drinking water, and the amount of bone tissue in the caps was quantified at three time points (4, 8 and 16 weeks). A continuously increased tissue fill was observed in all groups over time. The administration of minocycline-HCl as well as perforation of the calvaria increased this effect, especially with regard to mineralization. The strongest tissue augmentation, with 1.8 times that of the untreated control group, and, at the same time, the most mineralized tissue (2.3× over untreated control), was produced in the combination of both treatments, indicating that systemic administration of minocycline-HCl has an accelerating and enhancing effect on vertical bone augmentation.

Effects of Low Intensity Pulsed Ultrasound Stimulation on the Temporal Dynamics of Irradiated Bone Tissue Healing: A Histomorphometric Study in Rabbits.

The present study evaluated the influence of Low-Intensity Pulsed Ultrasound (LIPUS) on the regeneration processes of non-critical-size bone defects in irradiated and non-irradiated rabbit tibias. Bone defects were surgically created on both tibiae of six rabbits. The control group had no additional treatment. In one intervention group, one tibia was irradiated with 15 Gy in a single dose. A second group was treated with LIPUS, and a third with a combination of both treatments. The control samples showed 83.10% ± 17.79% of bone repair after 9 weeks, while the irradiated bone had regenerated significantly less during the same period (66.42% ± 29.36%). The LIPUS treatment on irradiated bones performed a 79.21% ± 21.07% bone fill and could not significantly improve the response compared to the non-treated irradiated specimens. However, LIPUS treatment on non-irradiated bone showed bone formations beyond the size defect (115.91% ± 33.69%), which was a highly significant increase when compared to the control group or any irradiated group. The application of ultrasound to healthy bone produced highly significant and enhanced bone formations with 36.70% more regenerated bone when compared to the same application on irradiated bone. LIPUS vibration stimuli may be considered as a promising complementary treatment approach in non-irradiated bone regeneration procedures to shorten the treatment and enhance bone healing. In irradiated bones, the effect of ultrasound application is less clear, and further studies are needed to refine the dynamics of the present results.

The Effects of Abutment Materials on Peri-Implant Soft Tissue Integration: A Study in Minipigs.

PURPOSE: To evaluate, in a minipig model, the soft tissue integration of four different transmucosal materials, as well as the peri-implant bone remodeling. MATERIALS AND METHODS: A total of 40 implants were placed in five minipigs in a single stage surgery, and two of each of the following abutment materials were used in each animal: (1) titanium (Ti; control), (2) polymethylmethacrylate (PMMA), (3) zirconia (Zi), and (4) veneering ceramic (VC). After a healing period of 3 months, the samples were collected and subjected to nondecalcified histology. The soft tissue dimensions (sulcus, junctional epithelium, and connective tissue attachment) were assessed on each abutment and the distance from the implant margin to first bone-to-implant contact (BIC) was measured. RESULTS: The mean biological width-characterized by the sum of junctional epithelium and connective tissue measurements-was 3.8 (0.6) mm and no statistically significant difference was found between the four groups (p = 0.41). However, a long junctional epithelium (3.3-3.8 mm) and a very short connective tissue attachment (0.1-0.2 mm) were observed with all abutments. The measured peri-implant bone remodeling was similar in all four groups (p = 0.88). CONCLUSIONS: Within its limitations, this study showed that all tested materials allowed soft tissue integration, consisting of a long junctional epithelium, extending close to the bone level, and a rather short portion of connective tissue.

Assessment of Disinfection Potential of Q-Switch Nd: YAG Laser on Contaminated Titanium Implant Surfaces.

Peri-implantitis (PI) is a relatively frequent pathology that compromises the overall survival of the dental implant. Adjunctive approaches for the conventional mechanical debridement are being suggested to optimize the treatment of PI. The goal of the study was the assessment of the disinfection potential of the Q-Switch Nd: YAG laser on contaminated titanium implant surfaces. A total of 72 sterile titanium discs were used and divided into three groups: 24 contaminated titanium discs treated with the laser (study Group L), 24 contaminated titanium discs with no treatment (control 1-Group C), and 24 sterile titanium discs with no treatment (control 2-Group S). Multi-species biofilm was used: Porphyromonas gingivalis, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, Streptococcus sobrinus, and Prevotella intermedia. Commensal bacteria were included also: Actinomyces naeslundii, Actinomyces viscosus, Streptococcus cristatus, Streptococcus gordonii, Streptococcus mitis, Streptococcus oralis, Streptococcus sanguinis, Streptococcus parasanguinis, and Veillonella parvula. Parameters delivered per pulse on the targeted surfaces of the titanium discs were an energy density of 0.597 J/cm2 each pulse, a pulse power of 270 mW, a laser beam spot of 2.4 mm in diameter, and a rate of repetition of 10 Hertz (Hz) for a pulse duration of 6 nanoseconds (ns). The mode was no contact, and a distance of 500 micrometers was used with a total time of irradiation equal to 2 s (s). The collection of microbiological samples was made for all groups; colony-forming units (CFU) were identified by two different practitioners, and the average of their examinations was considered for each sample. The average of the TBC (CFU/mL) was calculated for each group. Values were 0.000 CFU/mL, 4767 CFU/mL, and 0.000 CFU/mL for Group L, Group C, and Group S, respectively. Therefore, the suggested treatment protocol was able to provoke a total disinfection of the contaminated titanium surfaces. A statistical difference was only found between Group L vs. Group C and between Group S vs. Group C. The difference was not significant between Group S and Group L. In conclusion, the present study confirmed that the Q-Switch Nd: YAG laser under our specific conditions can provide a total disinfection of the contaminated titanium surfaces.

Clinical Performance of a Novel Two-Piece Abutment Concept: Results from a Prospective Study with a 1-Year Follow-Up.

Development of a stable and healthy soft-tissue barrier around dental implants is key to long-term success of implant-supported prostheses. The novel two-piece abutment concept shifts the prosthetic interface to the soft-tissue level to protect bone interface/connective tissue during the healing phase and restorative procedures. This prospective study included 72 patients treated with 106 implants to support a single-tooth or a three-unit bridge restored with two-piece abutments. The evaluation included marginal bone level change (MBLC), implant and prosthetic survival, soft-tissue health including keratinized mucosa height and mucosal margin position, patient quality of life (QoL) and satisfaction, and clinician satisfaction and ease-of-use rating of the concept. Mean MBLC from implant placement to 1 year was -0.36 ± 1.26 mm (n = 89), the 1-year implant and prosthetic survival rates were 97.1 and 96.7%, respectively, while keratinized mucosa height increased from 2.9 ± 1.2 mm at prosthetic delivery to 3.2 ± 1.3 mm, and mucosal margin migrated coronally by 0.49 ± 0.61 mm by 1 year. Patient satisfaction and QoL were high. Clinicians were satisfied with the esthetic and functional results and rated the concept as easy to use. In conclusion, the novel two-piece abutment concept promotes good peri-implant tissue health, while providing an easy-to-use workflow and high treatment satisfaction to both patients and clinicians.

Intraoperative and postoperative outcomes of sinus floor elevation using the lateral window technique versus the hydrodynamic transalveolar approach: a preliminary randomized controlled trial.

OBJECTIVES: To compare the clinical and radiographic outcomes of two sinus floor elevation techniques: the conventional lateral window technique versus the transalveolar approach using a hydrodynamic ultrasonic device. MATERIALS AND METHODS: The study was designed as a randomized controlled clinical trial, and participants were randomly allocated to the control group (lateral window: LW) or to the test group (hydrodynamic transalveolar approach: HTA). The intraoperative and postoperative data, including procedure duration and patient-reported outcome measures (PROMs), were collected during the surgery and up to 1 year post-surgery. Additionally, qualitative assessment of gained bone volumes and implant survival rates was recorded. RESULTS: Twenty-two patients were included in the study. The mean surgical time was significantly longer in the HTA compared to the LW group (48.1 ± 11.2 min vs. 35.2 ± 9.1 min, P = 0.0011). Perforation of the Schneiderian membrane occurred in 2/11 and 5/11 patients in the LW and the HTA group, respectively (P = 0.36). Postoperatively, higher morbidity and consumption of nonsteroidal anti-inflammatory drugs (NSAIDs) were associated with the LW group. However, self-reported satisfaction with surgical procedures was similar in the two groups. At 1 year, implant survival rates of 80% in the HTA group and 100% in the LW group were recorded (P = 0.12). CONCLUSIONS: Although the new transalveolar approach seems to reduce postoperative morbidity, an increased risk of intraoperative complications compared to the LW approach needs to be considered when choosing a technique. CLINICAL RELEVANCE: Our results provide new insights regarding clinical and radiographic outcomes of HTA and may help further determine indications for its use. TRIAL REGISTRATION: ClinicalTrivals.gov : NCT04499625.

Tunnel/Pouch versus Coronally Advanced Flap Combined with a Connective Tissue Graft for the Treatment of Maxillary Gingival Recessions: Four-Year Follow-Up of a Randomized Controlled Trial.

BACKGROUND: The long-term stability after soft tissue graft for covering gingival recession remains a pivotal goal for both patient and periodontist. Therefore, the aim of this study was to compare the four-year outcomes of the coronally advanced flap (CAF) versus the pouch/tunnel (POT) technique, both combined with connective tissue graft (CTG), for gingival recession treatment. METHODS: Forty patients were initially randomly assigned to the control group (CAF + CTG; N = 20) and the test group (POT + CTG; N = 20). Clinical outcomes included mean root coverage (MRC) and complete root coverage (CRC), gingival thickness (GT), and keratinized tissue (KT) gain. Esthetic outcomes were also analyzed using the pink esthetic score (PES) and patient-reported outcome measures (PROMs). All outcomes initially assessed at six months were extended to four years post-surgery. RESULTS: No significant differences were observed between the two patient groups in terms of MRC and CRC. At four years, significantly greater GT and KT gain were noted in the POT + CTG group, and tissue texture enhancement was also more prominent in the test group. CONCLUSIONS: The POT + CTG technique allows for long-term clinical coverage of gingival recessions comparable to that of the CAF + CTG technique, but it potentially improves gingival thickness, keratinized tissue and esthetic results.

Practical considerations for reducing mortality rates in alloxan-induced diabetic rabbits.

Chemically-induced diabetic animal models have been employed in many areas of diabetes mellitus (DM) research, but managing post-induction animal survival rates remains one of the main downsides. The aim of the present study was to propose a reliable approach to animal management and monitoring after DM induction in a rabbit model in order to reduce animal mortality rates. DM was induced by injecting alloxan in 12 New Zealand White rabbits. A preventive subcutaneous glucose administration to counteract a potentially lethal hypoglycemic phase following alloxan injection was performed on individual bases. Blood glucose level (BGL) was checked hourly for the first 36 h, then every 2 h until the hyperglycemic state was confirmed. All 12 rabbits survived a 48-hour post-induction phase. The critical hypoglycemic phase's start points and duration differed significantly among the rabbits, lasting from 6.7 to 37 h (19.75 ± 8.44). The rabbits entered the final hyperglycemic phase 18 h at the earliest and 42 h at the latest after induction (26.63 ± 7.07). The average daily BGLs throughout the study period ranged from 268 to 512 mg/dL (413.73 ± 76.69). Eleven rabbits survived until the end of the experiment. The variability of rabbits' responses to alloxan injection emphasizes the importance of monitoring rabbit behavior and thoroughly checking BGLs, followed by a preventive glucose administration based on rabbits' individual needs for up to 36 h after alloxan injection. The proposed approach seems to reduce animal mortality.

Clinical and radiographic assessment of circular versus triangular cross-section neck Implants in the posterior maxilla: A 1-year randomized controlled trial.

OBJECTIVES: Implants with a triangular neck were recently introduced to limit peri-implant bone loss. The primary objective of this randomized controlled trial was to compare peri-implant bone changes of circular versus triangular cross-section neck implants 1 year after loading. The secondary objectives were to assess buccal hard tissue thickness changes, Pink Esthetic Score (PES), and patient satisfaction. MATERIAL AND METHODS: Thirty four patients requiring replacement of the single, intercalated missing tooth of healed site for at least 4 months in the posterior maxilla were randomized into 2 groups according to the type of implant. Immediately after surgery and 1 year after final restoration, a cone beam CT (CBCT) was performed to assess proximal bone remodeling and buccal bone thickness. Peri-implant soft tissue health, PES, and patient-reported outcome measures (PROMs) were recorded. RESULTS: No implant loss occurred within the follow-up period. The mean ± SD peri-implant proximal bone loss 1 year after loading was 0.22 ± 0.30 mm for triangular and 0.42 ± 0.67 mm for circular implants necks (p = .25). Peri-implant bone loss exceeding 2 mm was observed in a single implant in the circular neck group. Buccal bone thickness remained stable and did not differ different between the 2 groups. The peri-implant soft tissue health, PES, and patient satisfaction were also comparable. CONCLUSIONS: Within the limitations of the present study, patient clinical and radiographic outcomes did not differ between triangular and circular cross-section neck implants in the posterior maxilla.

Maxillary implant overdenture retained by four unsplinted attachments and opposed by a natural or fixed dentition: One-year clinical outcomes.

OBJECTIVES: The aim of this prospective study was to evaluate the implant, prosthesis, and patient-reported outcomes of maxillary removable prostheses retained by 4 implant-supported study abutments after a follow-up period of 1 year in patients with natural teeth or a fixed rehabilitation in the mandible. MATERIALS AND METHODS: A total of 30 patients were included, and all received 4 implants in the upper maxilla. After 12 weeks, the prostheses were connected to the implant with unsplinted attachments. The implant and prosthodontics outcomes were assessed over a follow-up period of 1 year. Patient-reported outcome measures (PROMs) were evaluated with the Oral Health Impact Profile (OHIP-20) questionnaire and an adaptation of the McGill Denture Satisfaction Instrument using a visual analogue scale (VAS). RESULTS: A single patient dropped out. At the post-operative 12-week follow-up, 79.3% (95% CI: 64.6%-94.1%) of the patients displayed peri-implant mucosa hyperplasia and 69.0% (95% CI: 52.1%-85.8%) showed pain. After 1 year, 16 implants failed in 10 patients, leading to an implant survival rate of 86.2% (95% CI: 79.0%-92.5%), and the mean peri-implant bone loss was 1.01 ± 0.77 mm (95% CI: 0.85-1.16 mm). The prosthesis survival rate was 96.6% (95% CI: 82.2%-99.9%). The OHIP-20 and VAS scores both improved significantly from baseline to 1 year (p < .001). CONCLUSION: The implant survival rate was lower compared to the literature for the upper maxilla. Despite the encountered problems, PROMs showed significant improvement with the implant overdenture retained by 4 unsplinted implants compared to conventional dentures.

Hard and soft tissue analysis of alveolar ridge preservation in esthetic zone using deproteinized bovine bone mineral and a saddle connective tissue graft: A long-term prospective case series.

AIM: Although alveolar ridge preservation (ARP) procedures appear to limit bone resorption after dental extraction, long-term outcomes remain limited. The objective of this prospective case series was to evaluate the long-term hard and soft tissue changes after ARP procedure in the aesthetic area, using deproteinized bovine bone mineral (DBBM) and saddle connective tissue graft. MATERIALS AND METHODS: Fifteen patients were subjected to ARP and impressions and CT scans were taken at baseline and 3 months. After 5 to 7 years, a secondary long-term clinical and radiological analysis was carried out. Horizontal alveolar bone changes, soft tissue profiles and implant outcomes were assessed. RESULTS: Although a limited hard and soft tissue remodeling occurred during the first 3 months after ARP, from 3 months to the long-term evaluation, the alveolar bone dimensions remained stable and the soft tissue profiles significantly increased, in the more cervical levels. The implant survival rate after 5 to 7 years yielded 100% and peri-implant bone levels and soft tissue health were good. CONCLUSION: Within the limits of the study, the present data confirms the long-term effectiveness of ARP using DBBM and a saddle connective tissue graft offering stable hard and soft tissue conditions up to 5 to 7 years.

Q-Switch Nd:YAG Laser-Assisted Elimination of Multi-Species Biofilm on Titanium Surfaces.

(1) Background: The relatively high prevalence of peri-implantitis (PI) and the lack of a standard method for decontamination of the dental implant surface have pushed us to conduct further research in the field. Bacterial biofilms were found to play a primordial role in the etiology of PI. Therefore, the aim is to evaluate the efficacy of a laser-assisted elimination of biofilm protocol in the removal of a multi-species biofilm on titanium surfaces. (2) Methods: In total, 52 titanium discs (grade 4) were used. The study group consisted of 13 titanium disks contaminated with multi-species biofilms and subsequently irradiated with the laser (T + BF + L). The control groups consisted of the following types of titanium disks: 13 contaminated with multi-species biofilms (T + BF), 13 sterile and irradiated (T + L), 13 sterile and untreated (T). Q-Switch Nd:YAG laser Irradiation parameters were the following: energy density equal to 0.597 J/cm2 per pulse, power equal to 270 milliwatt per pulse, 2.4 mm of spot diameter, and 10 Hz repetition rate for pulse duration of six nanoseconds (ns). The laser irradiation was made during 2 s of total time in non-contact and at 0.5 mm away from the titanium disc surface. After treatment, presence of biofilms on the disks was evaluated by staining with crystal violet (CV), which was measured as optical density at six hundred thirty nm, and statistical analyses were done. (3) Results: the optical density values were 0.004 ± 0.004 for the study group T + BF + L, 0.120 ± 0.039 for group T + BF, 0.006 ± 0.003 for group T + L, and 0.007 ± 0.007 for group T. For the study group, laser treatment resulted in a total elimination of the biofilm, with mean values statistically significantly lower than those of contaminated titanium surfaces and similar to those of sterile titanium surfaces. (4) Conclusions: Our irradiation protocol provided a significant elimination of the multi-species biofilm on titanium surfaces. Laser treated titanium surfaces were biofilm-free, similar to the sterile ones.

A Randomized Comparative Clinical Study to Evaluate the Longevity of Esthetic Results of Gingival Melanin Depigmentation Treatment Using Different Laser Wavelengths (Diode, CO2, and Er:YAG).

Background: Gingival melanin hyperpigmentation is due to excessive deposition of melanin granules. The duration of pigmentation reappearance after treatment using different laser wavelengths remains controversial. Objective: The study aims to assess the longevity of gingival depigmentation (GD) and the consistency in esthetic results as three laser wavelengths (Er:YAG laser, CO2 laser, and diode laser, 980 nm) were used in two different groups (smokers and nonsmokers). This is attained by comparing the periods of time in each group before pigmentation reappearance. Methods: Seventy-two subjects were divided into daily smokers (S) and nonsmokers. Subjects underwent a randomized GD with: Erbium laser (Er), CO2 laser (CO2), and Diode laser (Diode). The subjects were divided into six groups: S and nonsmokers were treated with three different wavelengths. Irradiation was performed until there was no visible pigmentation. For qualitative measurement, Hedin Melanin Index (HMI) was used, before treatment, after 2 weeks, and until 60 months. Pigmentation reappearance of degree 1 or above of the HMI was noted. Descriptive statistics were also calculated. Results: HMI showed a 0 in all groups after 14 days of treatment. The time before pigmentation rebound was: Diode > CO2 > S-Diode > S-CO2 > Er > S-Er. The first signs of relapse shown among all groups were seen in the group S-Er group. The longest time before rebound was observed with the Diode group for the nonsmoker. Conclusions: Diode laser provides the longest-term stability in treatment. Smoking negatively affects the longevity of GD. Er laser gives the shortest time before the reappearance of gingival pigmentation.

Influence of implant scanbody material, position and operator on the accuracy of digital impression for complete-arch: A randomized in vitro trial.

PURPOSE: To evaluate the influence of implant scanbody (ISB) material, position and operator on the accuracy of a confocal microscopy intraoral scanning (IOS) for complete-arch implant impression. METHODS: An edentulous maxillary model with 6 internal hexagonal connection analogues was scanned with an extraoral optical scanner to achieve a reference file. Three ISBs made of different materials (polyetheretherketone (Pk), titanium (T) and Pk with a titanium base (Pkt)) were scanned with IOS by 3 operators. The resulting 45 test files were aligned to the reference file with a best fit algorithm. Linear (ΔX, ΔY and ΔZ-axis) and angular deviations (ΔANGLE) were assessed. Absolute values of the linear discrepancies were summed up to obtain a global measure of linear absolute error (ΔASS). Influence of ISB material, position and operator was statistically assessed using the mixed general linear model. RESULTS: At multivariate analysis, whenΔASS was considered as response variable, it was identified a significant influence of material (p<0.0001) and position (p=0.0009) while no significant operator effect was detected. When ΔANGLE was considered as response variable, material and position significantly influenced the expected ΔANGLE (p=0.0232 and p<0.0001) and no operator effect was identified. CONCLUSIONS: The investigated IOS for complete-arch digital impression was influenced by the ISB material with peek reporting the best results on both linear and angular measurements followed by titanium, peek-titanium resulting as the less accurate. Implant angulation affected significantly the linear deviations while implant position the angular deviations. Operator did not show any significant effect on the IOS accuracy.

Effect of Sintering on In Vivo Biological Performance of Chemically Deproteinized Bovine Hydroxyapatite.

The influence of the manufacturing process on physicochemical properties and biological performance of xenogenic biomaterials has been extensively studied, but its quantification on bone-to-material contact remains poorly investigated. The aim of this study was to investigate the effect of different heat treatments of an experimental chemically-deproteinized bovine hydroxyapatite in vivo in terms of new bone formation and osteoconductivity. Protein-free hydroxyapatite from bovine origin was produced under sub-critical conditions and then either sintered at 820 °C or 1200 °C. Structural and morphological properties were assessed by scanning electron microscopy (SEM), measurement of surface area and X-ray diffractometry (XRD). The materials were then implanted in standardized alveolar bone defects in minipigs and histomorphometric evaluations were performed using non-decalcified sections. Marked topographical differences were observed by SEM analysis. As the sintering temperature of the experimental material increased, the surface area significantly decreased while crystallite size increased. In vivo samples showed that the highly sintered BHA presented a significantly lower percentage of newly formed bone than the unheated one (p = 0.009). In addition, the percentage of bone-to-material contact (BMC) was significantly lowered in the highly sintered group when compared to the unsintered (p = 0.01) and 820 °C sintered (p = 0.02) groups. Non-sintered or sintered at 820 °C BHA seems to maintain a certain surface roughness allowing better bone regeneration and BMC. On the contrary, sintering of BHA at 1200 °C has an effect on its morphological and structural characteristics and significantly modify its biological performance (osteoconductivity) and crystallinity.

Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface.

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm2, pick powers density of 56 mW/cm2, 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.