Massimo Amato

Evaluation of Leakage of Bacteria and Endotoxins in Teeth Treated Endodontically by Two Different Techniques

Root canal recontamination occurs after contact between oral-bacterial flora and the coronal extremity of the root canal. The aim of this study was to evaluate the time required for endotoxins and bacteria to penetrate through root-canal obturations performed with vertical and lateral gutta-percha condensation techniques. Specimens prepared by the two alternative methods were exposed to contaminated saliva, and leakage into the root was evaluated over time. None of the obturated roots was infiltrated by endotoxins after 31 days. On the contrary, between day 13 and day 37 bacteria had infiltrated all specimens.

Effect of Nickel Chloride on Cell Proliferation

Objective: Metal alloys used in dentistry and in other biomedical fields may release nickel ions in the oral environment. The release of nickel might influence the normal biological and physiological processes, including tissue wound healing, cell growth and proliferation. The aim of this study was to evaluate in vitro the effects of nickel ions on cell cycle, viability and proliferation. Materials and Methods: Human osteosarcoma cells (U2OS) and human keratinocytes (HaCat) were exposed to different nickel chloride (NiCl2) concentrations (0 - 5mM) for various periods exposure. The viability of cultured cells was estimated by flow cytometry using Annexin V-FITC and Propidium Iodide (PI). Cell proliferation was evaluated by using carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) and flow cytometry. Finally, the effects of NiCl2 on cell cycle were assessed and quantified by flow cytometry. Statistical analysis was performed by means of ANOVA followed by Tukey’s test. Results: NiCl2 induced a dose and time dependent decrease in cell viability. After 24h, 1mM NiCl2 caused a similar and significant reduction of viability in U2OS and HaCat cells, while higher NiCl2 concentrations and longer exposure times showed a reduced cytotoxic effect in HaCat as compared to U2OS cells. Exposure to NiCl2 caused a dose- and time-dependent inhibition of cell proliferation in both cell lines tested, with a prominent effect on U2OS cells. Furthermore, both cell lines exposed to NiCl2 exhibited significant changes in cell cycle distribution after 24h exposure 2mM NiCl2, as compared to untreated cells (p<0.05). Conclusion: Our results indicate that release of nickel ions may affect cell proliferation. The inhibition of cell growth by NiCl2 is mediated by both cell cycle arrest and by induction of cell death.

New palatal distraction device by both bone-borne and tooth-borne force application in a paramedian bone anchorage site: surgical and occlusal considerations on clinical cases.

AbstractMaxillary constriction is a very common pathology with implications on dental occlusion, temporomandibular joint dysfunction, nasal breathing, and impairment on the smile and face esthetic.New techniques for expansion of the maxillary bones are particularly useful in relation to the new esthetic ideals of smile and face beauty.To achieve a bodily expansion of the maxillary bones, we developed a new rigid palatal distractor device with both tooth-borne and paramedian bone–borne anchorages to achieve a safe and simple anchorage site suitable also for orthodontic appliances.The reported cases show good results, with bodily maxillary expansion and cross-bite correction without any problems or complications. Substantial advantages of this new device and technique, in comparison with other commonly used palatal distractors, consisting of bodily maxillary movements, avoidance of relapse risks, and safe and simple screw insertion site for bone anchorage also suitable for orthodontic movements, are discussed.

In vitro cellular detoxification of triethylene glycol dimethacrylate by adduct formation with N-acetylcysteine

OBJECTIVE Various protective effects of N-acetylcysteine (NAC) against triethylene glycol dimethacrylate (TEGDMA)-induced cell damage have been demonstrated, but so far there is no evidence on NAC direct monomer detoxification mechanism. Here, we hypothesized that NAC might reduce TEGDMA cytotoxicity due to direct NAC adduct formation. METHODS We measured the cytotoxic effects of TEGDMA in presence and in absence of NAC by MTT test. Then we analyzed the presence of TEGDMA-NAC adduct formation in extracellular and intracellular compartments by capillary electrophoresis-UV detection (CE-UV) and capillary electrophoresis-mass spectrometry (CE-MS) analytical techniques. Moreover, we quantified the effective intracellular and extracellular TEGDMA concentrations through HPLC in the presence and absence of 10 mmol/L NAC. RESULTS TEGDMA reduced 3T3 cell vitality in a dose- and time-dependent manner, while NAC decreased monomer cytotoxicity and extracellular monomer concentrations by a direct reaction with TEGDMA. The adducts between the two molecules were detected both in the presence and absence of cell. Moreover a signal ascribed to the methacrylic acid was present in the CE-UV electropherogram of cellular lysates obtained after incubation with TEGDMA. SIGNIFICANCE Our results suggest that in vitro detoxification capability of NAC against TEGDMA-induced cell damage might occur also through the formation of NAC-TEGDMA adduct.

The thioredoxin system in the dental caries pathogen Streptococcus mutans and the food-industry bacterium Streptococcus thermophilus.

The Streptococcus genus includes the pathogenic species Streptococcus mutans, the main responsible of dental caries, and the safe microorganism Streptococcus thermophilus, used for the manufacture of dairy products. These facultative anaerobes control the levels of reactive oxygen species (ROS) and indeed, both S. mutans and S. thermophilus possess a cambialistic superoxide dismutase, the key enzyme for a preventive action against ROS. To evaluate the properties of a crucial mechanism for repairing ROS damages, the molecular and functional characterization of the thioredoxin system in these streptococci was investigated. The putative genes encoding its protein components in S. mutans and S. thermophilus were analysed and the corresponding recombinant proteins were purified. A single thioredoxin reductase was obtained from either S. mutans (SmTrxB) or S. thermophilus (StTrxB1), whereas two thioredoxins were prepared from either S. mutans (SmTrxA and SmTrxH1) or S. thermophilus (StTrxA1 and StTrxA2). Both SmTrxB and StTrxB1 reduced the synthetic substrate DTNB in the presence of NADPH, whereas only SmTrxA and StTrxA1 accelerated the insulin reduction in the presence of DTT. To reconstitute an in vitro streptococcal thioredoxin system, the combined activity of the thioredoxin components was tested through the insulin precipitation in the absence of DTT. The assay functions with a combination of SmTrxB or StTrxB1 with either SmTrxA or StTrxA1. These results suggest that the streptococcal members of the thioredoxin system display a direct functional interaction between them and that these protein components are interchangeable within the Streptococcus genus. In conclusion, our data prove the existence of a functioning thioredoxin system even in these microaerophiles.

La responsabilità professionale in odontoiatria: analisi di una casistica interdipartimentale

Riasunto Obiettivi L’incremento degli addebiti di responsabilita professionale in ambito sanitario, unitamente alla diffusione di dati espressivi di una differente distribuzione percentuale dei settori odontoiatrici coinvolti nel contenzioso, ha indotto gli autori a condurre un’analisi conoscitiva del fenomeno attraverso lo studio di una casistica interdipartimentale di accertata responsabilita professionale odontoiatrica in ambito civilistico. Materiali e metodi E stata condotta un’analisi descrittiva di tipo poliparametrico su un campione costituito da 436 casi di errata condotta odontoiatrica accertata, promossi da soggetti di eta compresa tra 14 e 70 anni. Risultati Il settore odontoiatrico in cui e piu frequentemente ravvisato un errore tecnico-deontologico e quello protesico e implantoprotesico, seguito da quelli endodontico- conservativo e ortognatodontico. Nella maggioranza dei casi si e accertata la carenza della documentazione sanitaria descrittiva dello stato anteriore, in assenza di un modulo di consenso informato al trattamento odontoiatrico. Il danno ha riguardato piu frequentemente strutture dentarie, concretizzandosi in un danno permanente alla persona ≤ 4% in oltre due terzi dei casi, con un importo del danno emergente quasi sempre (97%) Conclusioni Gli autori propongono un decalogo comportamentale al fine di ridurre i possibili addebiti di responsabilita professionale o, comunque, utile a documentare la corretta condotta tecnico- deontologica.

Intraoral epimucosal fixation for reducible maxillary fractures of the jaws; surgical considerations in comparison to current techniques.

Fractures of the jaw are often treated with rigid and stable internal fixation using plates or miniplates. Early surgery for jaw fractures is the optimal treatment; however, if a late treatment is begun, often the adoption of other protocols is needed. When the jaw fracture has one free bone fragment with 2 full-thickness lesions of mucoperiosteal soft tissues both on the buccal and palatal sides, the risk of resorption or necrosis is very high after elevating a mucoperiosteal flap for rigid fixation. For this reason, we developed an intraoral epimucosal fixation technique using self-locking screws and plates. Substantial advantages of this new technique, in comparison with other commonly used fixation techniques, consisted in the prevention of bone resorption or necrosis by safe and simple screw insertion procedure after manipulation of the fracture for reduction in closed surgery. Major indications for epimucosal fixation in closed surgery are the presence of jaw fractures without dislocation or reducible jaw fractures by manipulation particularly in edentulous patients.

µCT analysis of mandibular molars before and after instrumentation by Reciproc files

Cleaning and shaping are important section for the root canal treatment. A number of different methodologies have been developed to overcome these problems, including the introduction of rotary instruments nickel-titanium (NiTi). In endodontics NiTi have been shown to significantly reduce procedural errors compared to manual techniques of instrumentation. The efficiency of files is related to many factor. Although previous investigations that have used µCT analysis were hampered by insufficient resolution or projection incorrect. The new generation of μCT performance best offer, as micron resolution and accurate measurement software for evaluating the accurate anatomy of the root canal. The aim the paper was to evaluate the efficiency of Reciproc files in root canal treatment, evaluated before and after instrumentation by using μ-CT analysis.

Use of piezosurgery device in management of surgical dental implant complication: a case report.

An implant displacement into the maxillary sinus could be a complication of implant surgery in the upper jaw. In such cases, implant removal is needed to avoid the occurrence of sinus pathologies. Piezosurgery techniques could assure safer management of such complications because of clear surgical visibility and a selective ability to cut. The aim of this report is to present a case of an implant-related oral surgery complication that was resolved by means of a piezosurgery technique.

On the comparison of age determination methods based on dental development radiographic studies in a sample of Italian population

Abstract Objectives This study investigated the degree of reliability, complexity of use and possibility of further refinement of eight radiographic methods for the age determination of subjects in the growth phase, applied on a sample of Italian population. Materials and methods Each considered method was tested on a sample of 178 digitized panoramic radiographs (97 males and 81 females, aged 5 to 22 years). The obtained data were processed by statistical analysis. Results The overall Absolute Mean Error (AME) was on average equal to 0.89 years; within this error range fell approximately 61% of the subjects in our sample. The overall average of AME plus 1 standard deviation (SD) was equal to approximately 1.70 years, in the context of which fell about 84.5% of the sample investigated. Conclusions The statistical analysis of the data obtained by applying on our sample the considered methods showed, for each of them, the level of reliability in terms of absolute error with the relative SD (i.e., exact match between the age determined by the evaluators and the actual age, in terms of absolute value).