The medical device regulation (MDR) from a dental perspective

A new regulation for the marketing and application of medical devices has become applicable in the European Union as of May 2021. This regulation is termed EU 2017/745 or Medical Device Regulation (MDR). Initially published and entered into force in 2017, it replaces the former Medical Device Directive 93/42/EEC (MDD), but is still under amendment. The implication of this legislation has broad effects on manufacturers, importers, distributors, users of medical devices, and patients. This article discusses the MDR from the dental perspective. As is illuminated in this text, the MDR will create more red tape for industrial players to get their products CE (Conformitée Européenne) marked, and more documentation work for dentists. This also means that smaller companies acting out of Europe are affected in a disproportionally negative manner compared to their globally acting counterparts. The MDR could and most probably will result in a considerable reduction and price increase of the products that are available to European dentists. Moreover, the MDR could create a rift between dental materials scientists working at universities and the dental industry, because the latter now has to direct more money towards regulatory affairs rather than product development or innovation. On the other hand, the MDR may also act as an antetype for similar regulations in other parts of the world, and could offer new career opportunities for individuals in dental materials research, especially in the regulatory field

Hydrogen Peroxide Versus Sodium Hypochlorite: All a Matter of pH?

Introduction: Hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl) solutions are similar in that they contain oxidizing agents with a bleaching effect. NaOCl solutions are stable at a high pH, at which they also exert increased cleansing/proteolysis. On the other hand, H2O2 solutions are natively acidic, yet gain bleaching power on organic stains when alkalized. It was investigated whether alkalizing a H2O2 solution would also let it dissolve soft tissue or increase its bleaching power on blood-stained dentin. Methods: The stability of alkalized H2O2 solutions was assessed by iodometric titration. Soft tissue dissolution was investigated on porcine palatal mucosa. The bleaching effect (ΔL∗) after 60 minutes of exposure was monitored in blood-stained human dentin using a calibrated spectrophotometer. To compare similar molarities, 2.5% H2O2 solutions were used here, and 5.0% NaOCl was used as the positive control, whereas nonbuffered saline solution served as the negative control. Results: Adding alkali (NaOH) to the H2O2 solutions rendered them unstable in a dose-dependent manner. A H2O2 solution of pH 11.1 was chosen for the main experiments (tissue dissolution and bleaching effect) and compared with a native counterpart (pH = 4.7). Alkalizing the H2O2 solution had no discernible effect on its soft tissue dissolution or bleaching power (P = .75 compared with the native H2O2 solution). The NaOCl solution of similar molar concentration had a considerably (P < .001) higher tissue dissolving and bleaching effect under current conditions. Conclusions: The proteolytic/bleaching effects of NaOCl solutions are unique and cannot be achieved by altering the pH of peroxide solutions. Keywords: Bleaching; dentin; hydrogen peroxide; tissue dissolution

The Impact of Changing from First- to Fifth-Generation Nickel-Titanium Rotaries on Root-Filling Quality in a Clinical Undergraduate Course

In this retrospective study, it was investigated whether the use of a fifth-generation rotary system (ProTaper Next) resulted in improved radiological root filling quality compared to a first-generation counterpart (ProFile) in a controlled student course setting. Cases treated by fourth-year dental students in the 2020/21 academic year were collected and compared to those treated in 2019/20. Root canals in the former group were all instrumented using the ProTaper Next system, and the latter using the ProFile system. All other clinical parameters were similar between the two academic years, including the time of pre-clinical teaching, hands-on course hours, endodontic auxiliaries, and chemicals used for treatment. After excluding patients who were not available or refused to give their informed consent to this study (n = 20), and excluding teeth with missing or poor radiographs (n = 16), the fillings in 178 roots could be assessed by two calibrated observers blinded to the system that was used. The primary outcome was the radiographic quality of the root fillings according to the five-scale modified MOLANDER score. The secondary outcome was the number of separated rotary instruments by group. Both instrumenting systems resulted in a similar number of "excellent" root fillings (score I), 59 % in the ProTaper Next group and 60% in the ProFile group, with no statistically significant difference in outcome scores between groups (Probability > ChiSquare = 0.70). Furthermore, there was merely one separated instrument in the ProTaper Next group, and none in the ProFile group (Fisher's exact test, p = 1.00)

Stabilizing sodium hypochlorite at high pH: effects on soft tissue and dentin

NaOH-stabilized NaOCl solutions have a higher alkaline capacity and are thus more proteolytic than standard counterparts

Assessment of Irrigant Agitation Devices in Simulated Closed and Open Root Canal Systems

INTRODUCTION The in vitro efficacy of irrigant activation devices has not been contrasted to their safety. This was attempted in this study using apically closed versus patent simulated root canal systems in epoxy resin models, with the latter featuring a simulated periapical lesion. METHODS All 72 models had 2 joining canals connected by an isthmus, which was filled with dentin debris. The simulated periapical lesion was filled with colored gelatin in the 36 respective models. Canals were irrigated with 1.3% sodium hypochlorite. Samples were divided into 4 subgroups per system (n = 9): conventional irrigation, sonic low (EndoActivator; Dentsply Sirona, Charlotte, NC) and high frequency (EDDY; VDW, Munich, Germany), and ultrasonic agitation of the irrigant (always applying 3 cycles of 20 seconds). The total cleared surface areas (mm$^{2}$) in the simulated isthmus and periapical lesion were compared between systems and devices using parametric tests (P < .05). RESULTS The cleaning of the isthmus was more effective in the apically open compared with the closed systems and was also significantly influenced by the agitation method (P < .001). In the closed systems, EDDY and ultrasonic agitation achieved the significantly (P < .05) best cleaning of the isthmus. In the open systems, ultrasonic agitation showed the single best result (P < .05). EDDY caused by far the highest and ultrasonic agitation the lowest dissolution of the gelatin in the simulated periapical lesion. CONCLUSIONS Under the conditions of this study, ultrasonic agitation of a previously administered sodium hypochlorite irrigant was more laterally targeted and thus safer and more effective than sonic agitation methods

Indikationsbereiche von MTA, eine Übersicht

Mineral trioxide aggregate (MTA) has been used in dentistry for the last five to eight years. Because of its high biocompatibility, its good sealing ability, and the fact that cemental tissues grow on this material, it has a relatively wide range of applications in endodontics. MTA may be used to cap exposed vital pulps, to seal open apices or perforations, or as a retro-filling material in apical surgery. These applications are presented in the current article, and discussed based on case reports

The receptor activator of NF-κB ligand-osteoprotegerin system in pulpal and periapical disease

AIM: To summarize the collective in vitro, in vivo and clinical evidence of the involvement of the receptor activator of NF-κB ligand (RANKL)-osteoprotegerin (OPG) system, a system of two molecules controlling osteoclast differentiation and hard-tissue resorption, in pulpal and periapical pathophysiology. METHODOLOGY: A systematic search related to RANKL and/or OPG and pulp or periapical disease was conducted on Medline, Biosis, Cochrane, Embase and Web of Science databases using keywords and controlled vocabulary. No language restriction was applied. Two independent reviewers first screened titles and abstracts and then the full texts that were initially included. The reference lists of the identified publications were examined for additional titles. RESULTS: A total of 33 papers were identified. In vitro studies (N = 11) revealed that pulpal cells can be stimulated by various inflammatory agents to produce RANKL, whilst many studies did not consider the RANKL/OPG ratio. Animal studies (N = 9) mostly focused on the time course and development of periapical lesions in relation to the RANKL-OPG system. Levels of RANKL and OPG in the necrotizing pulp were not investigated. Human studies (N = 13) showed a steady-state expression of OPG in the odontoblast layer. Conflicting results have been reported regarding the role of RANKL in active apical periodontitis, again because the correlation of this molecule with its inhibitor (OPG) was often disregarded. CONCLUSIONS: There is relatively little information currently available that would highlight the specific role of RANKL and OPG in pulpal and periapical disease. OPG may play a protective role against internal resorption, whilst an increased periapical RANKL/OPG ratio might indicate bone resorption

Contrast-induced encephalopathy with acute stroke symptomatic: A case report

Background: Contrast induced encephalopathy is an infrequent complication of contrast media administration. It is usually transient but occasionally leads to permanent neurological deficits and death. Case presentation: We report here a case of non-ionic iodized contrast induced encephalopathy after an urgent coronary angiography, in a 62 year old woman who developed symptoms of acute stroke. Although diagnostic challenge and under not specific but supportive therapy the symptoms resolved completely within 72 hours without further complications. Conclusion: CIE is a rare entity whose frequency is dependent on the increasing use of diagnostic/interventional procedures with contrast media. The exclusion of more common complications of such procedures should be prompt. The clinical scenario is challenging and should be considered, in particular in high-risk patients. The course is generally benign and requires supportive therapy

Conversion of lanthanide glutarate chlorides with interstitial THF into lanthanide glutarates with unprecedented topologies

Using slow diffusion methods at room temperature (RT), we obtained four isomorphous lanthanide glutarate chlorides, accommodating interstitial THF and water molecules, [Ln2(Glut)2Cl2(H2O)8]•2H2O•THF (1 - 4), with Ln = La (1), Ce (2), Pr (3), Nd (4). They assemble as 3-dimensional (3D) lanthanide (Ln) coordination polymers with LnO10 coordination polyhedra. Their topology was elucidated to be a 4-coordinated sql net. 1 – 4 slowly dissolve in water liberating the entrapped THF molecules and reassemble as regular Ln-glutarate hydrates when the solution is deprived of THF and water by slow evaporation. The new products crystallize as [Ln2(Glut)3(H2O)3]•5H2O (5 - 7), with Ln = La (5), Ce (6), Pr (7), and [Nd2(Glut)3(H2O)2]•3.5H2O (8). 5 – 7 are isomorphous and crystallize as 3D-networks with two crystallographically independent LnO10 and LnO9 coordination spheres that assemble into Ln2O18 and Ln2O16 polyhedra via edge sharing. Their topology has not previously been observed and was found to be a 3,4,4,5,6-coordinated 3,4,4,5,6T61 net. The known compound 8 crystallizes also as a 3D-network and is isomorphous to other previously described lanthanide glutarate hydrates. 8 has a 3,4,5-coordinated 3,4,5T202 net topology, which has not been determined before