Domenico Baldi

Degenerative periodontal-diseases and oral osteonecrosis: The role of gene-environment interactions

Chronic-degenerative dentistry diseases, including periodontal diseases and oral osteonecrosis, are widespread in human populations and represent a significant problem for public health. These diseases result from pathogenic mechanisms created by the interaction between environmental genotoxic risk-factors and genetic assets conferring individual susceptibility. Osteonecrosis occurs in subjects undergoing exposure to high doses of DNA-damaging agents for chemo- and radiotherapy of neoplastic diseases. In susceptible patients, ionizing radiation and biphosphonate-chemotherapy induce severe, progressive, and irreversible degeneration of facial bones, resulting in avascular necrosis of the jaw. This may also occur in patients receiving biphosphonate for osteoporosis therapy. Periodontal diseases include chronic, aggressive, and necrotizing periodontitis, often resulting in severe alteration of periodontal tissues and tooth loss. Cigarette smoking and chronic inflammation caused by specific bacteria are the main risk factors for periodontitis. Oxidative damage plays a fundamental pathogenic role, as established by detection of mitochondrial DNA damage in the gingival tissue of patients with periodontitis. Endogenous risk factors in dental diseases include polymorphisms for metabolic enzymes such as glutathione transferases M1 and T1, N-acetyl transferase 2, and CYP 1A1. Other genetic polymorphisms that confer susceptibility to dentistry diseases affect genes encoding metalloproteases (involved in periodontal tissue remodeling and degradation), cytokines (involved in inflammation), prothrombin, and DNA repair activities. These findings provide evidence that dentistry diseases are related to risk factors associated with environmental mutagenesis. This issue warrants future investigations aimed at improving oral health and preventing oral degenerative diseases using molecular and experimental approaches currently utilized in mutagenicity studies.

Ultrasonic Implant Site Preparation Using Piezosurgery: A Multicenter Case Series Study Analyzing 3,579 Implants with a 1- to 3-Year Follow-Up

This multicenter case series introduces an innovative ultrasonic implant site preparation (UISP) technique as an alternative to the use of traditional rotary instruments. A total of 3,579 implants were inserted in 1,885 subjects, and the sites were prepared using a specific ultrasonic device with a 1- to 3-year follow-up. No surgical complications related to the UISP protocol were reported for any of the implant sites. Seventy-eight implants (59 maxillary, 19 mandibular) failed within 5 months of insertion, for an overall osseointegration percentage of 97.82% (97.14% maxilla, 98.75% mandible). Three maxillary implants failed after 3 years of loading, with an overall implant survival rate of 97.74% (96.99% maxilla, 98.75% mandible).

Influence of Different Surface Characteristics on Peri-implant Tissue Behavior: A Six-Year Prospective Report.

PURPOSE The aim of this study was to evaluate the behavior of hard and soft tissue around implants with different surface treatments. MATERIALS AND METHODS Eight patients were identified for this study. Each patient received at least 2 implants (1 control, 1 test) into an edentulous quadrant, for a total of 10 pairs of implants. Two types of implants were used: hybrid implants (control) with a dual acid-etched surface in their apical portion and a machined coronal part, and test implants with an acid-etched surface throughout their entire length. Standardized periapical radiographs were taken at baseline, 3 months, 6 months, and 1 year post implant placement and then annually until the 6-year follow-up. Bleeding on probing (BOP) and Plaque Index (PI) were recorded annually. Probing depth (PD) was recorded at the 6-year follow-up. RESULTS Moderate crestal bone remodeling was observed during the 1-year postimplant placement evaluation (P=.001), and test implants revealed smaller marginal bone resorption (P=.030). No significant changes in bone level were observed between the 1-year and the 6-year follow-up appointments, and a significantly smaller bone resorption was found at test implants. No statistically significant differences in bone resorption were found between maxilla and mandible. No statistically significant differences were detected between test and control implants for BOP, PI, or PD. CONCLUSIONS The preliminary results suggest that implant surface characteristics might affect the bone remodeling phase subsequent to the surgical trauma. However, once osseointegration was established, implant surfaces did not affect bone maintenance over time. Implant surfaces did not affect soft tissue behavior. The results of this pilot study need to be confirmed in a study with a larger sample size and over a longer time frame.

Dental implants osteogenic properties evaluated by cDNA microarrays.

Objective:This study aims at applying cDNA microarray analysis in vitro for establishing and comparing the osteogenic properties of dental implants with different surface characteristics. Materials and Methods:Saos-2 osteoblasts were cultured in bottom-cone tubes in presence of 5 different dental implants with various surface characteristics. Cells adherent to dental implants were detached and RNA purified. The expression of 18,401 genes was tested by cDNA microarray. Results:The number and viability of cells adherent to different dental implants varied but without any significant statistical difference. Conversely, gene expression was revealed to be a more sensitive biomarker being remarkably different in cells adherent to different implants. The 5 dental implants significantly modulated the expression of 14 osteogenic activities mainly including bone morphogenetic proteins, osteomodulin, and osteoprotegerin. Conclusion:Despite no significant differences having been found in in vitro cell number and viability, cells adherent to 5 differently surfaced implants showed different gene expression profiles. Thus, to evaluate osteogenesis as related to dental implants, it is important to analyze not only the number of adherent cells but also the activation of genes encoding for osteogenic activities.

Morphological and chemical characteristics of different titanium surfaces treated by bicarbonate and glycine powder air abrasive systems.

Objectives:This in vitro study investigated possible morphological and chemical changes induced by glycine or sodium bicarbonate powder air polishing on machined and acid-etched titanium surfaces. Materials and Methods:The glycine powder (granulometry <65 &mgr;m) and sodium bicarbonate powder (granulometry <150 &mgr;m) were applied on 2 machined healing abutments and on 2 acid-etched healing abutments. The samples were characterized by scanning electron microscopy coupled with energy dispersive x-ray spectroscopy. The analyses were performed at different steps: (1) as received, right after opening the abutment packaging; (2) after 20 minutes air exposure; (3) after aging in artificial saliva; (4) after glycine or sodium bicarbonate powder air polishing for 5 seconds; (5) after repetition of steps 3 and 4 with longer time of polishing (20 seconds). Conclusions:Air polishing using glycine and sodium bicarbonate powder seemed to be safe for professional oral hygiene of titanium dental implants, although acid-etched abutments and abutments treated with bicarbonate harbored more salts. This might indicate a greater plaque accumulation in a clinical situation. However, this result has to be investigated in vivo to understand its clinical relevance.

Correlation between insertion torque and implant stability quotient in tapered implants with knife-edge thread design

Aim To evaluate the correlation between insertion torque (IT) and implant stability quotient (ISQ) in tapered implants with knife-edge threads. Methods Seventy-five identical implants (Anyridge, Megagen) were inserted by using a surgical drilling unit with torque control and an integrated resonance frequency analysis module (Implantmed, W&H). IT (N/cm) and ISQ were recorded and implants were divided into three groups (n = 25) according to the IT: low (<30), medium (30 < IT < 50), and high torque (>50). ISQ difference among groups was assessed by Kruskal-Wallis test, followed by Bonferroni-corrected Mann–Whitney U-test for pairwise comparisons. The strength of the association between IT and ISQ was assessed by Spearman Rho correlation coefficient (α = 0.05). Results At the pairwise comparisons, a significant difference of ISQ values was demonstrated only between low torque and high torque groups. The strength of the association between IT and ISQ value was significant for both the entire sample and the medium torque group, while it was not significant in low and high torque groups. Conclusions For the investigated implant, ISQ and IT showed a positive correlation up to values around 50 N/cm: higher torques subject the bone-implant system to unnecessary biological and mechanical stress without additional benefits in terms of implant stability. This trial is registered with NCT03222219.

A 4-Year Retrospective Radiographic Study of Marginal Bone Loss of 156 Titanium Implants Placed with Ultrasonic Site Preparation

This retrospective study evaluated implant survival rate (SR) and marginal bone loss around dental implants placed with ultrasonic implant site preparation. A total of 156 implants were placed in 28 totally and partially edentulous patients. Bone loss was measured on intraoral paralleling digital radiographs taken at the impression phase and after 4 years of loading. As 3 implants (1.92%) failed at the second surgery stage, the SR was 98.08% after 4 years. The mean marginal bone loss was 0.52 ± 0.33 mm (0.51 ± 0.35 mm mesially and 0.53 ± 0.35 mm distally), with comparable values for implants inserted into the maxilla (0.52 ± 0.32 mm) and the mandible (0.52 ± 0.35 mm).

Immediate Loading of Implant-Supported Single Crowns after Conventional and Ultrasonic Implant Site Preparation: A Multicenter Randomized Controlled Clinical Trial

Aim To compare implant survival rate and marginal bone loss (MBL) of immediately loaded single implants inserted by using ultrasonic implant site preparation (UISP) (test) and conventional rotary instrumentation (control). Methods Two single implants were inserted for each patient: after randomization, test site was prepared by using an ultrasonic device (Piezosurgery Touch, Mectron, Italy) and control site was prepared by using the drills of the selected implant system (Premium AZT, Sweden & Martina, Italy), until reaching a final diameter of 3 mm in both groups. Identical implants (3.8x11.5 mm) were inserted in all sites at crestal level. Impressions were taken and screwed resin single crowns with platform-switched provisional abutments were delivered with 48 hours. Periapical radiographs were taken at provisional crown insertion (T0), 6 months (T1) and one year (T2) after prosthetic loading to measure MBL. All data were tested for normality and subsequently analyzed by paired samples t-test and forward multiple linear regression. Results Forty-eight patients were treated in six centers with the insertion of ninety-six implants (48 test; 48 control). Four implants in four patients failed within the first six months of healing (two in test group; two in control group; no difference between groups). Forty patients (age 60.1±10.7 years; 22 female, 18 male) were included in the final analysis. Mean MBL after six months of loading was 1.39±1.03 mm in the test group and 1.42±1.16 mm in the control group (p>0.05) and after one year was 1.92±1.14 mm and 2.14±1.55 mm in test and control, respectively (p>0.05). Conclusions No differences in survival rate and MBL were demonstrated between UISP and conventional site preparation with rotary instruments in immediately loaded dental implants: UISP, with its characteristics of enhanced surgical control and safety in proximity of delicate structures, may be used as a reliable alternative to the traditional drilling systems.

Evaluation of a new ultrasonic insert for prosthodontic preparation

PURPOSE This paper describes a new ultrasonic instrument (tipholder DB1 with crown prep tip inserts) designed to optimize prosthodontic margin repositioning and finishing. MATERIALS AND METHODS The insert movement was assessed, and it was demonstrated that tipholder DB1 provides its inserts with an elliptical-like movement, making the entire insert surface able to cut. Then, 20 extracted teeth were prepared using tipholder DB1, sonic instruments, and traditional drills. Dental surface roughness produced using each of the three tools was measured using a roughness tester. Results were compared using univariate analysis of variance and Bonferroni post hoc test. RESULTS The roughness produced using tipholder DB1 with crown prep insert presented no statistically significant differences compared to the roughness produced using sonic instruments and traditional drills. CONCLUSION Tipholder DB1 with crown prep inserts is a promising treatment for margin repositioning and finishing.