Endodontic Medicine has gained more attention and is becoming a more important issue in Endodontics. As an example, more than one hundred articles on this topic have been published in the last eight years. Several of these studies have found an association between endodontic variables, that is the prevalence of apical periodontitis, the prevalence of root canal treatment (RCT) and the outcome of RCT assessed as root filled teeth (RFT) with radiolucent periapical lesions (RPL) or non‐retained RFT, and several systemic diseases, such as diabetes, cardiovascular disease, smoking habits, osteoporosis, inherited coagulopaties, biological medications, low birth weight or physical fitness. However, the demonstration of association does not prove by itself the existence of a cause–effect relationship. Two variables can be related statistically to each other without either variable directly affecting the values of the other thus resulting in a non‐causal relationship. Causality is assumed when one variable is shown to contribute to the development of the other, and its removal is shown to reduce the frequency of disease. Therefore, once a significant statistical association has been found between two variables, it is necessary to exclude the presence of bias, which would imply that the association is artefactual, and to analyse if the causation criteria defined by Hill (Proceedings of the Royal Society of Medicine 1965; 58: 295‐300) are fulfilled to establish a causal relationship. Only if they are satisfied, can it be concluded that the association is causal. The aim of this study was to analyse the difference between association and causation, applying the criteria of causality to the specific case of the association between endodontic disease and diabetes mellitus.

Previous studies have found an association between the outcome of root canal treatment (RCT) and diabetic status. This systematic review and meta‐analysis aimed to analyse the potential relationship between diabetes and the occurrence of extracted root filled teeth (RFT). The clinical PICO question was as follows: in adult patients with RFT, does the absence or presence of diabetes influence the prevalence of RFT extraction? The key words used in the systematic search were as follows: (Diabetes OR Diabetes Mellitus OR Hyperglycaemia OR Diabetic) AND (Endodontic OR Endodontics OR Endodontic Treatment OR Root Canal Treatment OR Root Canal Preparation OR Root Canal Therapy OR Root Filled Teeth OR Endodontically Treated Teeth) AND (Extraction OR Retention OR Survival OR Success OR Failure OR Outcome). The primary outcome variable was odds ratio (OR) for the frequency of extracted RFT in diabetics and healthy subjects. The method of DerSimonian–Laird with random effects was used to calculate the overall OR. Three hundred titles were identified, and three studies achieved the inclusion criteria. Data from 54 936 root canal treatments, 50 301 in nondiabetic control subjects and 4635 in diabetic patients, were analysed. The calculated overall odds ratio (OR = 2.44; 95% CI = 1.54–3.88; P = 0.0001) implies that diabetics had a significantly higher prevalence of extracted RFT than healthy nondiabetic subjects. The results of available studies indicate a significant relationship between DM and increased frequency of nonretained root filled teeth. Diabetes mellitus should be considered an important preoperative prognostic factor in root canal treatment.

Titanium surface is an important factor in achieving osseointegration during the early wound healing of dental implants in alveolar bone. The purpose of this study was to evaluate sandblasted-etched surface implants to investigate the osseointegration. In the present study, we used two different types of sandblasted-etched surface implants, an SLA™ surface and a Nanoblast Plus™ surface. Roughness and chemical composition were evaluated by a white light interferometer microscope and X-ray photoelectron spectroscopy, respectively. The SLA™ surface exhibited the higher values (Ra 3.05 μm) of rugosity compared to the Nanoblast Plus™ surface (Ra 1.78 μm). Both types of implants were inserted in the femoral condyles of ten New Zealand white rabbits. After 12 weeks, histological and histomorphometric analysis was performed. All the implants were osseointegrated and no signs of infection were observed. Histomorphometric analysis revealed that the bone–implant contact % (BIC) ratio was similar around the SLA™ implants (63.74 ± 13.61) than around the Nanoblast Plus™ implants (62.83 ± 9.91). Both implant surfaces demonstrated a favorable bone response, confirming the relevance of the sandblasted-etched surface on implant osseointegration.