Risk factors associated with the longevity of multi-rooted teeth. Long-term outcomes after active and supportive periodontal therapy

AIM To investigate risk factors for the loss of multi-rooted teeth (MRT) in subjects treated for periodontitis and enrolled in supportive periodontal therapy (SPT). MATERIAL AND METHODS A total of 172 subjects were examined before (T0) and after active periodontal therapy (APT)(T1) and following a mean of 11.5 ± 5.2 (SD) years of SPT (T2). The association of risk factors with loss of MRT was analysed with multilevel logistic regression. The tooth was the unit of analysis. RESULTS Furcation involvement (FI) = 1 before APT was not a risk factor for tooth loss compared with FI = 0 (p = 0.37). Between T0 and T2, MRT with FI = 2 (OR: 2.92, 95% CI: 1.68, 5.06, p = 0.0001) and FI = 3 (OR: 6.85, 95% CI: 3.40, 13.83, p < 0.0001) were at a significantly higher risk to be lost compared with those with FI = 0. During SPT, smokers lost significantly more MRT compared with non-smokers (OR: 2.37, 95% CI: 1.05, 5.35, p = 0.04). Non-smoking and compliant subjects with FI = 0/1 at T1 lost significantly less MRT during SPT compared with non-compliant smokers with FI = 2 (OR: 10.11, 95% CI: 2.91, 35.11, p < 0.0001) and FI = 3 (OR: 17.18, 95% CI: 4.98, 59.28, p < 0.0001) respectively. CONCLUSIONS FI = 1 was not a risk factor for tooth loss compared with FI = 0. FI = 2/3, smoking and lack of compliance with regular SPT represented risk factors for the loss of MRT in subjects treated for periodontitis.

Climate refugia: joint inference from fossil records, species distribution models and phylogeography

Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial–interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia – fossil records, species distribution models and phylogeographic surveys – in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate.

Diurnal cycle of fossil and nonfossil carbon using radiocarbon analyses during CalNex

Radiocarbon (14C) analysis is a unique tool to distinguish fossil/nonfossil sources of carbonaceous aerosols. We present 14C measurements of organic carbon (OC) and total carbon (TC) on highly time resolved filters (3–4 h, typically 12 h or longer have been reported) from 7 days collected during California Research at the Nexus of Air Quality and Climate Change (CalNex) 2010 in Pasadena. Average nonfossil contributions of 58% ± 15% and 51% ± 15% were found for OC and TC, respectively. Results indicate that nonfossil carbon is a major constituent of the background aerosol, evidenced by its nearly constant concentration (2–3 μgC m−3). Cooking is estimated to contribute at least 25% to nonfossil OC, underlining the importance of urban nonfossil OC sources. In contrast, fossil OC concentrations have prominent and consistent diurnal profiles, with significant afternoon enhancements (~3 μgC m−3), following the arrival of the western Los Angeles (LA) basin plume with the sea breeze. A corresponding increase in semivolatile oxygenated OC and organic vehicular emission markers and their photochemical reaction products occurs. This suggests that the increasing OC is mostly from fresh anthropogenic secondary OC (SOC) from mainly fossil precursors formed in the western LA basin plume. We note that in several European cities where the diesel passenger car fraction is higher, SOC is 20% less fossil, despite 2–3 times higher elemental carbon concentrations, suggesting that SOC formation from gasoline emissions most likely dominates over diesel in the LA basin. This would have significant implications for our understanding of the on-road vehicle contribution to ambient aerosols and merits further study.

Localization of impacted maxillary canines and root resorption of neighbouring teeth: a study assessing the diagnostic value of panoramic radiographs in two groups of observers.

OBJECTIVES To assess the diagnostic value of panoramic views (2D) of patients with impacted maxillary canines by a group of trained orthodontists and oral surgeons, and to quantify the subjective need and reasons for further three-dimensional (3D) imaging. MATERIALS AND METHODS The study comprises 60 patients with panoramic radiographs (2D) and cone beam computed tomography (CBCT) scans (3D), and a total of 72 impacted canines. Data from a standardized questionnaire were compared within (intragroup) and between (intergroup) a group of orthodontists and oral surgeons to assess possible correlations and differences. Furthermore, the questionnaire data were compared with the findings from the CBCT scans to estimate the correlation within and between the two specialties. Finally, the need and reasons for further 3D imaging was analysed for both groups. RESULTS When comparing questionnaire data with the analysis of the respective CBCT scans, orthodontists showed probability (Pr) values ranging from 0.443 to 0.943. Oral surgeons exhibited Pr values from 0.191 to 0.946. Statistically significant differences were found for the labiopalatal location of the impacted maxillary canine (P = 0.04), indicating a higher correlation in the orthodontist group. The most frequent reason mentioned for the further need of 3D analysis was the labiopalatal location of the impacted canines. Oral surgeons were more in favour of performing further 3D imaging (P = 0.04). CONCLUSIONS Orthodontists were more likely to diagnose the exact labiopalatal position of impacted maxillary canines when using panoramic views only. Generally, oral surgeons more often indicated the need for further 3D imaging.

Soft tissue wound healing around teeth and dental implants.

AIM To provide an overview on the biology and soft tissue wound healing around teeth and dental implants. MATERIAL AND METHODS This narrative review focuses on cell biology and histology of soft tissue wounds around natural teeth and dental implants. RESULTS AND CONCLUSIONS The available data indicate that: (a) Oral wounds follow a similar pattern. (b) The tissue specificities of the gingival, alveolar and palatal mucosa appear to be innately and not necessarily functionally determined. (c) The granulation tissue originating from the periodontal ligament or from connective tissue originally covered by keratinized epithelium has the potential to induce keratinization. However, it also appears that deep palatal connective tissue may not have the same potential to induce keratinization as the palatal connective tissue originating from an immediately subepithelial area. (d) Epithelial healing following non-surgical and surgical periodontal therapy appears to be completed after a period of 7–14 days. Structural integrity of a maturing wound between a denuded root surface and a soft tissue flap is achieved at approximately 14-days post-surgery. (e) The formation of the biological width and maturation of the barrier function around transmucosal implants requires 6–8 weeks of healing. (f) The established peri-implant soft connective tissue resembles a scar tissue in composition, fibre orientation, and vasculature. (g) The peri-implant junctional epithelium may reach a greater final length under certain conditions such as implants placed into fresh extraction sockets versus conventional implant procedures in healed sites.

Osteo-odonto-keratoprosthesis (OOKP) and the testing of three different adhesives for bonding bovine teeth with optical poly-(methyl methacrylate) (PMMA) cylinder.

AIM Preparation of the lamina during osteo-odonto-keratoprosthesis (OOKP) design is complex, and its longevity and watertightness important. To date, only acrylic bone cements have been used for bonding the optical cylinder to the tooth dentine. Our aim was to evaluate different dental adhesives for OOKP preparation. METHODS Specimens of bovine teeth were produced by preparing 1.5-mm thick dentine slices with holes having a diameter of 3.5 mm. Each group (n=10 per group) was luted with either classic poly-(methyl methacrylate) (PMMA) bone cement, universal resin cement or glass ionomer cement. All specimens underwent force measurement using a uniaxial traction machine. RESULTS The highest mean force required to break the bond was measured for PMMA bone cement (128.2 N) followed by universal resin cement (127.9 N), with no statistically significant difference. Glass ionomer cement showed significantly lower force resistance (78.1 N). CONCLUSIONS Excellent bonding strength combined with easy application was found for universal resin cement, and thus, it is a potential alternative to acrylic bone cement in OOKP preparation.

Crestal bone changes at teeth and implants in periodontally healthy and periodontally compromised patients. A 10-year comparative case-series study

BACKGROUND Limited data exist on the longitudinal crestal bone changes around teeth compared with implants in partially edentulous patients. This study sought to compare the 10-year radiographic crestal bone changes (bone level [BL]) around teeth and implants in periodontally compromised (PCPs) and periodontally healthy (PHPs) patients. METHODS A total of 120 patients were evaluated for the radiographic crestal BL around dental implants and adjacent teeth at time of implant crown insertion and at the 10-year follow-up. Sixty patients had a previous history of periodontitis (PCPs), and the remaining 60 were PHPs. In each category (PCP and PHP), two different implant systems were used. The mean BL change at the implant and at the adjacent tooth at the interproximal area was calculated by subtracting the radiographic crestal BL at the time of crown cementation from the radiographic crestal BL at the 10-year follow-up. RESULTS At 10 years after therapy, the survival rate ranged from 80% to 95% for subgroups for implants, whereas it was 100% for the adjacent teeth. In all eight different patient categories evaluated, teeth demonstrated a significantly more stable radiographic BL compared with adjacent dental implants (teeth BL, 0.44 ± 0.23 mm; implant BL, 2.28 ± 0.72 mm; P <0.05). Radiographic BL changes around teeth seemed not to be influenced by the presence or absence of advanced bone loss (≥3 mm) at the adjacent implants. CONCLUSIONS Natural teeth yielded better long-term results with respect to survival rate and marginal BL changes compared with dental implants. Moreover, these findings also extend to teeth with an initial reduced periodontal attachment level, provided adequate periodontal treatment and maintenance are performed. As a consequence, the decision of tooth extraction attributable to periodontal reasons in favor of a dental implant should be carefully considered in partially edentulous patients.

Morphologic characteristics, location, and associated complications of maxillary and mandibular supernumerary teeth as evaluated using cone beam computed tomography.

OBJECTIVES To evaluate the location and morphologic characteristics of supernumerary teeth and to assess the frequency and extent of root resorption of adjacent teeth using cone beam computed tomography (CBCT). MATERIALS AND METHODS CBCT scans of 82 patients with supernumerary teeth in the maxilla and mandible were evaluated by two orthodontists independently. Data regarding the type, shape, and three-dimensional (3D) location of the supernumeraries including the frequency and extent of root resorption of adjacent teeth were recorded and evaluated for possible associations. RESULTS The study comprised a total of 101 supernumerary teeth. Most of the patients (80.5 per cent) exhibited one single supernumerary tooth, while 15.8 per cent had two and 3.7 per cent had three supernumeraries. Males were affected more than females with a ratio of 1.65:1. Mesiodentes were the most frequently diagnosed type of supernumerary teeth (48.52 per cent), followed by supernumerary premolars (23.76 per cent) and lateral incisors (18.81 per cent). Supernumeraries were most commonly conical in shape (42.6 per cent) with a normal or inclined vertical position (61.4 per cent). Root resorption of adjacent teeth was detected for 22.8 per cent of the supernumerary teeth, most frequently for supernumerary premolars. There was a significant association between root resorption of adjacent teeth and type and shape of tooth. Interrater agreement for the measurements performed showed kappa values ranging from 0.55 to 1 with a kappa value of 1 for type and shape of the supernumerary teeth. CONCLUSIONS CBCT provides 3D information about location and shape of supernumerary teeth as well as prevalence and degree of root resorption of neighbouring teeth with moderate to high interrater correlation.

Salivary Contamination and Decontamination: Bond Strength to Dentin of Primary and Permanent Teeth

Aim: To evaluate the effects of salivary contamination and decontamination on bond strength of two one-step adhesives to primary and permanent dentin. Methods: Dentin specimens were prepared from extracted primary and permanent molars (210 of each) and were distributed to seven groups (n=15/group/molar type) for each adhesive (Xeno V+ and Scotchbond Universal): no saliva contamination (control); saliva contamination before or after light-curing of the adhesives followed either by air-drying, by rinsing with water and air-drying, or by rinsing with water, air-drying and reapplication of the adhesives. Resin composite was applied and the specimens were stored for 24h (37°C, 100% humidity). Then, shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA and Wilcoxon rank sum tests. Results: Saliva contamination reduced SBS of Xeno V+, the reduction being more pronounced when contamination occurred before light-curing than after. In both situations, decontamination involving reapplication of the adhesive restored SBS. Saliva contamination had no significant effect on Scotchbond Universal. There were no differences in SBS between primary and permanent teeth. Conclusion: Saliva contamination reduced SBS of Xeno V+, but not of Scotchbond Universal. SBS was restored when contaminated dentin was rinsed with water and air-dried followed by reapplication of the adhesive.

Effect of Salivary Contamination and Decontamination on Bond Strength of Two One-Step Self-Etching Adhesives to Dentin of Primary and Permanent Teeth

Purpose: To evaluate the effects of human saliva contamination and two decontamination procedures at different stages of the bonding procedure on the bond strength of two one-step self-etching adhesives to primary and permanent dentin. Materials and Methods: Extracted human primary and permanent molars (210 of each) were ground to mid-coronal dentin. The dentin specimens were randomly divided into 7 groups (n = 15/group/molar type) for each adhesive (Xeno V+ and Scotchbond Universal): no saliva contamination (control); saliva contamination before or after light curing of the adhesives followed by air drying, rinsing with water spray/air drying, or by rinsing with water spray/air drying/reapplication of the adhesives. Resin composite (Filtek Z250) was applied on the treated dentin surfaces. The specimens were stored at 37°C and 100% humidity for 24 h. After storage, shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA followed by exact Wilcoxon rank sum tests. Results: Xeno V+ generated significantly higher SBS than Scotchbond Universal when no saliva contamination occurred. Saliva contamination reduced SBS of Xeno V+, with the reduction being more pronounced when contamination occurred before light curing than after. In both situations, decontamination involving reapplication of the adhesive restored SBS. Saliva contamination had no significant effect on Scotchbond Universal. There were no differences in SBS between primary and permanent teeth. Conclusion: Rinsing with water and air drying followed by reapplication of the adhesive restored bond strength to saliva-contaminated dentin.

Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013

During winter 2013, extremely high concentrations (i.e., 4–20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) mass concentrations (24 h samples) were found in four major cities in China including Xi'an, Beijing, Shanghai and Guangzhou. Statistical analysis of a combined data set from elemental carbon (EC), organic carbon (OC), 14C and biomass-burning marker measurements using Latin hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. Based on 14C measurements of EC fractions (six samples each city), we found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% across all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xi'an (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10 and 48 ± 9% of OC and total carbon (TC), respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8, 48 ± 18, 53 ± 4 and 65 ± 26% of non-fossil OC for Xi'an, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass-burning emissions. For each site, we also compared samples from moderately to heavily polluted days according to particulate matter mass. Despite a significant increase of the absolute mass concentrations of primary emissions from both fossil and non-fossil sources during the heavily polluted events, their relative contribution to TC was even decreased, whereas the portion of SOC was consistently increased at all sites. This observation indicates that SOC was an important fraction in the increment of carbonaceous aerosols during the haze episode in China.

In vitro performance of a pen-type laser fluorescence device and bitewing radiographs for approximal caries detection in permanent and primary teeth.

AIM To evaluate the performance of a pen‑type laser fluorescence device (DIAGNOdent 2190; LFpen, KaVo, Germany) and bitewing radiographs (BW) for approximal caries detection in permanent and primary teeth. MATERIALS AND METHODS A total of 246 anterior approximal surfaces (102 permanent and 144 primary) were selected. Contact points were simulated using sound teeth. Two examiners assessed all approximal surfaces using LFpen and BW. The teeth were histologically assessed for the reference standard. Optimal cut‑off limits were calculated for LFpen for primary and permanent teeth. Sensitivity, specificity, accuracy and area under the receiver operating characteristic curve (Az) were calculated for D1 (enamel and dentin lesions) and D3 (dentin lesions) thresholds. The reproducibility was assessed by intraclass correlation coefficient (ICC) and Cohen's weighted kappa values. RESULTS For permanent teeth, the LFpen cut‑off were 0- 27 (sound), 28- 33 (enamel caries) and >33 (dentin caries). For primary teeth, the LFpen cut‑off were 0- 7 (sound), 8- 32 (enamelcaries) and >32 (dentin caries). The LFpen presented higher sensitivity values than BW for primary teeth (0.58 vs. 0.32 at D1 and 0.80 vs. 0.47 at D3) and permanent teeth (0.80 vs. 0.57 at D1 and 0.94 vs. 0.51 at D3). Specificity did not show a significant difference between the methods. Rank correlations with histology were 0.59 and 0.83 (LFpen) and 0.36 and 0.70 (BW) for primary and permanent teeth, respectively, considering all lesions. ICC values for LFpen were 0.71 (inter) and 0.86 (intra) for permanent teeth and 0.94 (inter) and 0.90/0.99 for primary teeth. Kappa values for BW were 0.69 (inter) and 0.68/0.90 (intra) for permanent teeth and 0.64 (inter) and 0.89/0.89 for primary teeth. CONCLUSION LFpen presented better reproducibility for primary and permanent teeth and higher accuracy in detecting caries lesions at D1 threshold than BW for permanent teeth. LFpen should be used as an adjunct method for approximal caries detection.

Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex

Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively.

Wet deposition of fossil and non-fossil derived particulate carbon: insights from radiocarbon measurement

Radiocarbon (14C) measurements of both organic carbon (OC) and elemental carbon (EC) allow a more detailed source apportionment, leading to a full and unambiguous distinction and quantification of the contributions from non-fossil and fossil sources. A thermal-optical method with a commercial OC/EC analyzer to isolate water-insoluble OC (WIOC) and EC for their subsequent 14C measurement was applied for the first time to filtered precipitation samples collected at a costal site in Portugal and at a continental site in Switzerland. Our results show that WIOC in precipitation is dominated by non-fossil sources such as biogenic and biomass-burning emissions regardless of rain origins and seasons, whereas EC sources are shared by fossil-fuel combustion and biomass burning. In addition, monthly variation of WIOC in Switzerland was characterized by higher abundance in warm than in cold seasons, highlighting the importance of biogenic emissions to particulate carbon in rainwater. Samples with high particulate carbon concentrations in Portugal were found to be associated with increased biogenic input. Despite the importance of non-fossil sources, fossil emissions account for approximately 20% of particulate carbon in wet deposition for our study, which is in line with fossil contribution in bulk rainwater dissolved organic carbon as well as aerosol WIOC and EC estimated by the 14C approach from other studies.