Force decay evaluation of thermoplastic and thermoset elastomeric chains: A mechanical design comparison

Objectives:To compare the following over a period of 8 weeks: (1) force decay between thermoplastic (TP) and thermoset (TS) elastomeric chains; (2) force decay between light (200-g) and heavy (350-g) initial forces; and (3) force decay between direct chains and chain loops (stretched from one pin around the second pin and back to the first pin).Materials and Methods:TP and TS chains were obtained from American Orthodontics™ (AOTP, AOTS) and ORMCO™ (OrTP, OrTS). Each of the four chain groups was subdivided into four subgroups with 10 specimens per subgroup: (1) direct chains light force, (2) direct chains heavy force, (3) chain loops light force, and (4) chain loops heavy force. The experiment was performed in artificial saliva (pH of 6.75) at 37°C.Results:A significant difference was found between TP and TS chains, with an average mean difference of around 20% more force decay found in the TP chains (P < .001, α  =  .05). There was no significant difference between direct chains and chain loops except in OrTP, in which direct chains showed more force decay. There was also no significant difference in force decay identified when using light vs heavy forces.Conclusions:TS chains decayed less than TP chains, and chain loop retraction was beneficial only when using OrTP chains. Contrary to the interchangeable use of TP and TS chains in the published literature and in clinical practice, this study demonstrates that they perform differently under stress and that a clear distinction should be made between the two.     

The in vitro biomechanics of anterior arch expansion using fixed lingual appliances with coil springs or archwire stops

Introduction

The presented study investigates differences in the biomechanics of straight and mushroom fixed lingual appliances when implementing coil springs and stops for anterior arch expansion.

Materials and Methods

An in vitro orthodontic simulator was used to measure three-dimensional forces and moments on each tooth of a simulated maxillary arch. Mushroom and straight archwire forms of 0.016″ NiTi round archwire were considered, using 0.010″ × 0.030″ NiTi open coils and 0.016″-0.018″ archwire stops (n = 44 per group). Teeth in the anterior dental arch were moved from a neutral to crowded position to replicate anterior crowding of central and lateral incisors. Forces and moments of interest for lateral incisors and first premolars were compared using repeated measures mixed multivariate analysis of variance (α = 0.05).

Results

Three comparisons between straight versus mushroom archwires and two comparisons of coil springs vs. stops were not statistically significant. Overall, it was found that the use of a straight lingual archwire produced larger differences in forces and moments between using stops and coil springs than when using a mushroom archwire. Using stops produced larger forces and moments for both types of archwires as compared to using coil springs. The largest expansion forces were produced using straight archwires with stops, exceeding 3.0 N of force. Straight archwires with coil springs produced the lowest expansion forces on lateral incisors, just exceeding 1.5 N.

Conclusions

The findings of this study have elucidated significant differences in the biomechanics of transverse arch expansion using straight or mushroom fixed lingual appliances with coil springs or stops.     

Effects of Pulpectomy on the Amount of Root Resorption during Orthodontic Tooth Movement

Introduction

Previous studies have revealed that orthodontic force affects dental pulp via the rupture of blood vessels and vacuolization of pulp tissues. We hypothesized that pulp tissues express inflammatory cytokines and regulators of odontoclast differentiation after excess orthodontic force. The purpose of this study was to investigate the effects of tensile force in human pulp cells and to measure inflammatory root resorption during tooth movement in pulpless rat teeth.

Methods

After cyclic tensile force application in human pulp cells, gene expression and protein concentration of macrophage colony-stimulating factor, receptor activator of nuclear factor kappa-B ligand, interleukin-1 beta, and tumor necrosis factor alpha were determined by real-time polymerase chain reaction and enzyme-linked immunoassay. Moreover, the role of the stretch-activated channel was evaluated by gadolinium (Gd³⁺) treatment. The upper right first molars of 7-week Wistar rats were subjected to pulpectomy and root canal filling followed by mesial movement for 6 months.

Results

The expression of cytokine messenger RNAs and proteins in the experimental group peaked with loading at 10-kPa tensile force after 48 hours (P < .01). Gd³⁺ reduced the expression of these cytokine messenger RNAs and protein concentrations (P < .01). The amount of inflammatory root resorption was significantly larger in the control teeth than the pulpectomized teeth (P < .05).

Conclusions

This study shows that tensile forces in the pulp cells enhance the expression of various cytokines via the S-A channel, which may lead to inflammatory root resorption during tooth movement. It also suggests that root canal treatment is effective for progressive severe inflammatory root resorption during tooth movement.     

The effect of orthodontic forces on calcitonin gene-related peptide expression in human dental pulp

Introduction

The purpose of this study was to quantify the effect of moderate and severe orthodontic forces on calcitonin gene-related peptide (CGRP) expression in healthy human dental pulp.

Methods

Thirty human dental pulp samples were obtained from healthy premolars in which extraction was indicated for orthodontic reasons. Before extraction, teeth were divided into 3 groups of 10 premolars each: (1) the control group: healthy premolars without application of orthodontic forces; (2) the moderate force group: a 56-g force was applied to the premolars for 24 hours; and (3) the severe force group: a 224-g force was applied to the premolars for 24 hours. All dental pulp samples were processed, and CGRP was measured by radioimmunoassay.

Results

Greater CGRP expression was found in the severe force group followed by the moderate force group. The lower CGRP values were for the control group. The Kruskal-Wallis test showed statistically significant differences between groups (P < .0001). Least significant difference (LSD) post hoc tests showed statistically significant differences in CGRP expression between the control group and the severe force group (P < .0001) but not with the moderate force group (P = .06). Differences between the moderate and severe force groups were statistically significant (P < .0001).

Conclusions

CGRP expression in human dental pulp increases when teeth are submitted to severe orthodontic forces.     

In vitro fracture strength and patterns in root‐filled teeth restored with different base materials

Background

There is little research on the effects of an intermediate base on the fracture strength of root‐filled teeth. This study compared the fracture strengths and patterns of root‐filled teeth restored with intermediate bases of glass‐ionomer cement (GIC), zinc polycarboxylate cement (ZPC), dual‐cured resin composite (DCRC) and Biodentine^® under resin composite.

Methods

Standardized cavities were prepared in 100 extracted human maxillary and mandibular premolars, and root canal treatment was performed. The teeth were stratified and randomly allocated to five groups (n = 20): (i) GIC; (ii) ZPC; (iii) DCRC; (iv) Biodentine; and (v) prepared but unrestored (control). The teeth were subjected to an oblique, ramped load until fracture. The fracture loads, level, mode and location were recorded.

Results

Mean fracture strengths of all restored groups were not significantly different amongst the groups. There were significant overall effects on mean fracture strength for tooth type (P = 0.002) and buccolingual width of the crown (P = 0.001).

Conclusions

The four materials were appropriate intermediate bases. The laminate restorative technique promoted fracture strengths that are likely to withstand normal and maximum masticatory function. The base material can influence failure mode, which may have implications for the clinical presentation of fractures of root‐filled teeth.     

In Vitro Assessment of Torque and Force Generated by Novel ProTaper Next Instruments during Simulated Canal Preparation

Introduction

The purpose of this study was to assess torque and force for simulated canal preparation with a new root canal instrument, ProTaper Next.

Methods

Six sets of ProTaper Next Instruments (X1–X5) were used to prepare 36 artificial canals. Files were divided into 6 groups. Different settings of rotations per minute (250, 300, and 350 rpm) and numbers of in-and-out movements to reach working length (3 or 4 insertions [ins]) were applied in each group (250 rpm/3 ins, 250 rpm/4 ins, 300 rpm/3 ins, 300 rpm/4 ins, 350 rpm/3 ins, and 350 rpm/4 ins) by using an automated torque bench. Peak torques (Ncm) as well as positive and negative forces (N) were registered. Analysis of variance and Tukey post hoc tests were applied. Preliminary data for angle and stationary torque at failure were also obtained and compared with peak torque for each instrument.

Results

Significant differences in peak torque (P < .0001), positive force (P < .002), and negative force (P < .0001) were found for ProTaper Next instruments overall. X2 showed the highest torque with all settings. X5 showed the highest positive force in all groups. X1 and X2 showed the highest negative forces for all groups except for 350 rpm/4 ins. Significantly lower torque (P < .0001) and positive force (P < .007) were measured in the group 350 rpm/4 ins for all instruments except for X4. In contrast, X1 showed a significantly lower negative force for 350 rpm/4 ins. Torque at failure according to American Dental Association no. 28/ISO 36030-1 was lower for X1, X2, and X3 than torque during simulated canal preparation (P < .0001).

Conclusions

Under the conditions of this study, using ProTaper Next at 350 rpm and with 4 in-and-out movements resulted in lowest levels of peak torque as well as positive and negative forces.     

Calcium phosphate precipitation in experimental gaps between fluoride‐containing fast‐setting calcium silicate cement and dentin

A novel fast‐setting calcium silicate cement containing fluoride (novel‐CSC) has been developed for applications in tooth crowns. The aim of this study was to assess the ability of the novel‐CSC to close the experimental gaps at the dentin–cement interface. The novel‐CSC was tested against Vitrebond and GC Fuji II LC. Experimental gaps of 50 or 300 μm width were created between the materials and dentin. Specimens with the 300‐μm‐wide gap were immersed in phosphate‐buffered saline and the closed gap area was measured during 96 h. All specimens with 50 or 300 μm gap width were analyzed by scanning electron microscopy equipped with energy dispersive X‐ray spectroscopy (SEM/EDX) to assess the morphology and chemical composition of the precipitates after 96 h immersion in phosphate‐buffered saline. High‐resolution micro‐computed tomography (μCT) was used to evaluate the integrity and continuity of the precipitiates after 96 h and 180 d. In all novel‐CSC samples, precipitates closed the gap area completely after 96 h. The SEM/EDX revealed that the globular precipitates closing the gap area were mainly composed of calcium and phosphorus. After 180 d, μCT indicated thicker precipitates compared with initial precipitates only in the novel‐CSC group, whereas no precipitates were observed in resin‐modified glass ionomers. Novel‐CSC promoted continuous precipitation of calcium phosphate, including apatite, and closed the experimental gaps.     

Class II composite restoration technique teaching: A randomised controlled crossover laboratory-based trial involving a novel ringless sectional matrix technique

Introduction

Objectives were to assess how different techniques (including a novel ringless sectional matrix approach) affect students' restorative outcomes, and their preferences for and preparedness to clinically implement new techniques with the aim of introducing appropriate techniques to the undergraduate curriculum.

Materials and Methods

Students performed two class II composite restorations in plastic teeth using two sectional matrix techniques (separating ring vs. without [ringless]), and two composite restorative techniques (incremental vs. injection-moulded bulk-fill). Restorations were assessed on multiple parameters which were combined to rate them as “good” or not. Online surveys assessed students' preferences for and preparedness to clinically implement new techniques.

Results

Contact area concavity (OR = 106, p < .001) and cervical marginal overhang (OR = 7.4, p < .001) were much more likely with the separating ring compared to the ringless sectional matrix technique. “Good” restorations were 29.5 times more likely when using ringless compared to separating ring techniques and 3.3 times more likely when using the injection-moulding bulk-fill compared to layered composite technique. A majority of students preferred the ringless to separating ring sectional matrix technique and the injection-moulding bulk-fill to layered composite technique. Large majorities felt prepared to implement the new techniques clinically with no or minimal guidance.

Conclusions

A classic sectional matrix technique with separating ring resulted in a much greater occurrence of contact area concavity and cervical marginal overhang than a novel ringless approach. When allied with student preferences and clinical preparedness, inclusion of the novel ringless approach in the undergraduate curriculum can be supported alongside bulk-fill injection-moulding techniques.     

Double-Crown Prosthesis Retention Using Polyetherketoneketone (PEKK): An In Vitro Study

Purpose

To assess the retentive force of telescopic crowns using polyetherketoneketone (PEKK) high-performance polymer in relation to conventional materials over a long period of time in an in vitro setting.

Materials and Methods

Thirty-six sets of primary and secondary crowns were fabricated as per the double crown-retained prostheses approach. Six samples were included in each of the five test groups (1: zirconia/PEKK [Zr/PEKK]; 2: titanium/PEKK [Ti/PEKK]; 3: cobalt-chrome/PEKK [CoCr/PEKK]; 4: PEKK/PEKK; and 5: gold/PEKK [Au/PEKK]) and the single control group (gold/galvano-gold [Au/GA]). The insertion-removal test was performed for 20,000 cycles, and the surface condition was observed. Retentive forces were analyzed using two-way ANOVA (α<0.05).

Results

The retention forces in groups Zr/PEKK and Ti/PEKK significantly decreased over time (group 1: p = 0.035 and group 2: p = 0.001), whereas retentive force increased significantly in groups PEKK/PEKK, Au/PEKK, and control (group 4: p = 0.001, group 5: p = 0.008, and control: p = 0.042). Similar wear was observed on the primary crown in groups PEKK/PEKK, gold/PEKK, and control.

Conclusions

Groups PEKK/PEKK and Au/PEKK showed a transition of retentive force similar to the control group. Groups PEKK/PEKK and Au/PEKK had similar wear on the surface compared to control. Therefore, PEKK has a promising clinical potential.     

Influence of ozone on the composite-to-composite bond

The study evaluated the effect of ozone application on the composite-to-composite bond. Three hundred and twenty cylindrical composite specimens were divided into two groups: group 1 was subjected to a 60 s ozone application, whereas group 2 remained untreated. Four subgroups were obtained from each group according to the intermediate repair agent: an adhesive, a silane, silane/adhesive combination, or flowable composite. Repair composite cylinders were built-up. The composite repair strength was tested after 24 h and after thermocycling with a shear test. Additionally, 4 mm × 4 mm × 2 mm composite specimens were prepared and stored 24 h in deionized water. Half of the specimens were subjected to ozone application and the other served as control. The elastic modulus (E) and the Vicker’s hardness (VH) of the composite surfaces were tested immediately and after thermocycling. Significant differences among the experimental groups were detected (p < 0.001). The composite repair strength was affected by the pretreatment and by the intermediate agent, whereas, the thermocycling was not significant. The partial eta-squared statistics showed that the intermediate agent was the main factor affecting the composite repair strength, whereas the pretreatment played a minor role. No differences were observed between ozone and control groups when the same intermediate agent and the same aging conditions were applied. Repairing with flowable composite tended to achieve higher bond strengths (20.7 and 26.5 MPa in ozone and control groups, respectively, after 24 h). The use of silane coupling agent showed the lowest composite repair strengths. Ozone did not affect E and VH (p > 0.05) and the thermocycling affected only E (p < 0.05). In conclusion, the application of ozone does not impair the composite-to-composite bond.     

In Vitro Comparison in a Manikin Model: Increasing Apical Enlargement with K3 and K3XF Rotary Instruments

Introduction

The aim of the study was to compare the K3 and K3XF systems (SybronEndo, Glendora, CA) after 1 and 2 uses by evaluating apical transportation, working length loss, and working time in a manikin model.

Methods

Mesial canals of 40 extracted first mandibular molars were instrumented. Radiographs taken after instrumentation with #25, #30, #35, and #40 files were superimposed on the preoperative image in both mesiodistal and buccolingual angulations. AutoCAD (Autodesk Inc, San Rafael, CA) was used to measure working length loss and apical transportation at 0, 0.5, and 1 mm from the working length (WL). The working time was measured. Group comparison was analyzed using post hoc Tukey honestly significant difference tests (P < .05).

Results

No significant differences were found in apical transportation, working length loss between K3 and K3XF systems, or between the number of uses. Significant differences were found when canal enlargement was performed to a #35–40 (P < .05). K3 instrumentation performed significantly faster (29.6 ± 15.4) than with the K3XF system (40.2 ± 17.7) (P < .05). No differences were observed in working time when comparing the number of uses.

Conclusions

K3 and R-phase K3XF rotary systems shaped curved root canals safely with minimal apical transportation, even up to a 40/04 file.     

High serum procalcitonin levels in patients with periodontitis and chronic migraine

1 Background

To evaluate the contribution of chronic periodontitis (CP) to serum procalcitonin (proCT) levels in chronic migraine (CM) patients in a cross‐sectional study.

2 Methods

We included 138 subjects divided into 4 groups based on clinical features of CM and periodontal parameters: systemically and periodontally healthy individuals (n = 37), systemically healthy and CP patients (n = 19), CM and periodontally healthy patients (n = 34), and CM+CP patients (n = 48). Demographic, neurological, clinical data as well as full‐mouth periodontal records were obtained. ProCT and high sensitive C‐reactive protein (hs‐CRP) serum levels were determined from blood samples taken during migraine interictal period.

3 Results

Patients from the CP+CM group (0.056±0.006 ng/mL) had significantly higher serum proCT levels in comparison with the systemically and periodontally healthy group (0.029±0.019 ng/mL), CM group (0.041±0.002 ng/mL), or CP group (0.034±0.014 ng/mL) (p < 0.001). There were no significant differences in hs‐CRP between groups (p = 0.081). Multiple linear regression analysis showed that CP was associated with increased proCT levels in CM patients (R² = 0.293, p < 0.001).

4 Conclusions

CP independently contributes to elevated serum proCT levels in CM patients. These findings suggest that CP could play a role in migraine chronification.     

Influence of surface roughness on streptococcal adhesion forces to composite resins

Objective

To determine streptococcal adhesion forces with composite resins with different surface roughness.

Methods

Polishing and grinding were applied to obtain smooth (roughness 20 nm), moderately rough (150 nm) and rough (350 nm) surfaces of two orthodontic, light-cured composites. Adhesion forces between Streptococcus sanguinis and Streptococcus mutans and the composite surfaces were measured using atomic force microscopy in absence or presence of a salivary conditioning film. Initial adhesion forces were measured as well adhesion after 120 s of contact, as longer contact times are known to result in stronger adhesion forces (“bond-strengthening”). Surface roughness in absence and presence of salivary conditioning films were compared using ANOVA, while adhesion forces were subjected to a Weibull analysis.

Results

Initial adhesion forces in absence of a salivary conditioning film amounted between −0.7 and −0.9 nN for smooth composite resins and increased between −1.0 and −2.0 nN for the roughest surfaces. Streptococcal adhesion forces after bond-strengthening were significantly stronger than upon initial contact, irrespective of the composite type. Salivary conditioning films significantly decreased the surface roughness of the composites, as well as the streptococcal adhesion forces. Yet, also in the presence of a conditioning film, rougher composite surfaces exerted stronger adhesion forces, irrespective of composite type or bacterial strain.

Conclusion

Streptococcal adhesion forces to orthodontic composite resins increase with increasing roughness of the composite surfaces. Composite surface roughness less affects adhesion forces with S. mutans than with S. sanguinis.     

An in vitro investigation of the effect of bevel design on the penetration and withdrawal forces of dental needles

Objectives

To compare the effect on insertion and withdrawal forces using needles with a standard atraumatic bevel to those with a novel asymmetrical bevel in vitro.

Methods

Maximum needle penetration forces were measured using a 10 N load cell mounted on an Instron universal testing machine. Forces were determined during insertion through a 0.4 mm polyurethane membrane mounted at 90° (n = 30 of each design), 30° (n = 16 of each design) and 150° (n = 16 of each design) to the needle bevel and during a 10 mm insertion into a polyvinyl siloxane block mounted at 90° to the bevel (n = 16 of each design). In all tests the rate of insertion was 50 mm/min.

Results

The novel design required less force to penetrate the membrane at 30° and 150° compared to the standard design (mean forces at 30° being 0.75 N and 0.98 N for novel and standard designs respectively [p < 0.001] and at 150° 0.52 N and 0.66 N respectively [p < 0.001] but more force at 90° penetration tests (0.60 N and 0.46 N respectively [p < 0.001]). The novel design required less force to insert 10 mm into the polyvinyl siloxane (1.80 N and 2.54 N respectively [p < 0.001]).

Conclusion

The novel design needed less force than the standard version to penetrate a thin membrane when used at 30° and 150° to the surface and to penetrate a polyvinyl siloxane block to a depth of 10 mm but required more force to penetrate a thin membrane at 90°.

Clinical significance

Needle bevel design affects the penetration and withdrawal forces of dental needles in vitro.     

Human periodontal ligament cells exhibit no endotoxin tolerance upon stimulation with Porphyromonas gingivalis lipopolysaccharide

Background/Objectives

Endotoxin tolerance is characterized by a state of hyporesponsiveness after confrontation with endotoxins such as lipopolysaccharides (LPS) at low concentrations. The aim of this study was to investigate, whether pretreatment with Porphyromonas gingivalis leads to endotoxin tolerance induction and possible alterations in toll‐like receptor (TLR) 2‐ and 4‐induced response in human periodontal ligament cells (hPDLCs).

Material and Methods

Primary hPDLCs were pretreated with P. gingivalis (0.1 or 0.3 μg/mL) LPS for 24 hours and afterwards treated with one of the following stimuli: P. gingivalis LPS (1 μg/mL); TLR4 agonist Escherichia coli LPS (0.1 μg/mL; 1 μg/mL); TLR2 agonist Pam3CSK4 (0.1 μg/mL; 1 μg/mL). The protein expression of interleukin (IL)‐6, IL‐8 and monocyte chemotactic protein‐1 was analyzed with quantitative polymerase chain reaction and enzyme‐linked immunosorbent assay. Gene expression levels of TLR2 and TLR4 were determined by quantitative polymerase chain reaction.

Results

Pretreatment of cells with low concentrations of P. gingivalis LPS did not result in lower production of IL‐6, IL‐8 and monocyte chemotactic protein‐1 compared to control group. In some cases, pretreated cells exhibited lower gene expression levels of TLR2 and TLR4 compared to non‐pretreated cells.

Conclusion

The results of this study implicate that hPDLCs do not develop endotoxin tolerance. Furthermore, the amplitude of the inflammatory response shows no significant dependency on TLR2 and TLR4 expression levels.     

Titanium‐prepared platelet‐rich fibrin provides advantages on periodontal healing: A randomized split‐mouth clinical study

1 Background

The aim of this study to evaluate the contributions of titanium‐prepared platelet‐rich fibrin (T‐PRF) combined with open flap debridement (OFD) on biological markers in gingival crevicular fluid (GCF)and periodontal outcomes.

2 Methods

Twenty‐nine participants with chronic periodontitis were treated either with autologous T‐PRF+OFD or OFD alone. GCF growth factor levels and relative receptor activator nuclear factor kappa‐B/osteoprotegerin (RANKL/OPG) ratio at baseline and 2, 4, and 6 weeks postoperatively were analyzed, and clinical parameters such as probing depth (PD), relative attachment level (RAL) and gingival margin level (GML) at baseline and 9 months after surgery were compared.

3 Results

The mean PD reduction, RAL gain, and GML change were significantly greater in the OFD+T‐PRF sites than in the OFD sites (P = 0.033, P = 0.029, and P = 0.026, respectively). Both groups demonstrated increased growth factor levels at week 2 compared with baseline, followed by reductions at weeks 4 and 6. GCF growth factor levels in the test group were seen at higher concentrations with respect to control group until 6 weeks post‐surgery. During this 6‐week period, relative RANKL/OPG ratio was found significantly lower in the OFD+T‐PRF group compared to the OFD group(P < 0.05).

4 Conclusions

Using T‐PRF membrane combined with OFD provided significantly higher concentrations of growth factors and lower RANKL/OPG ratio in GCF for approximately 4 to 6 weeks, and improved periodontal healing compared to conventional flap sites.     

Restoration techniques and marginal overhang in Class II composite resin restorations

Objectives

The objective of the study was to compare in vitro interproximal overhang formation of Class II composite resin restoration when using different matrix systems.

Methods

240 lower left molar phantom head teeth with an MO-preparation were divided into 12 groups (n = 20). In six groups a circumferential matrix (Tofflemire X-thin matrix, HaweNeos 1001-c, SuperCap) was used, combined with either a hand-instrument (PFI49 or OptraContact) or separation ring (Composi-Tight Gold). In the other six groups two sectional matrix systems were used (flexible and dead-soft), with three separation rings (Composi-Tight Gold, Contact Matrix, Palodent BiTine). Matrices were secured with wooden wedges and preparations were restored with composite resin Clearfil AP-X (Kuraray) placed and polymerized in increments. After matrix removal overhang was measured on a standardized digital macroscopic image in mm². For analysis a multiple linear regression model was used.

Results

Use of circumferential matrices resulted in less overhang than sectional matrices (−0.85 mm², p < 0.001). A flexible matrix led to less overhang than dead-soft matrices (−0.54 mm², p < 0.001), and no difference was found between straight and pre-contoured matrices (p = 0.945). The insertion of the OptraContact resulted in a much increased overhang of 2.54 mm² (p < 0.001). The Composi-Tight Gold and the Contact Matrix System rings resulted in less overhang, −0.69 and −0.68 mm², respectively (both p < 0.001), whereas the Palodent BiTine ring did not.

Conclusions

Use of circumferential matrices or sectional flexible matrices resulted in the least marginal overhang when combined with a Contact Matrix separation ring or a Composi-Tight Gold ring.     

Platelet indices (mean platelet volume and platelet distribution width) have correlations with periodontal inflamed surface area in coronary artery disease patients: A pilot study

1 Background

The plausible mechanisms regarding the relationship between periodontitis and coronary artery disease (CAD) has long been the focus of studies. This study aimed to test the hypothesis that higher periodontal inflamed surface area (PISA) values have positive correlations with increased complete blood parameters in patients with CAD.

2 Methods

Patients who underwent coronary angiography with a suspicion of CAD between the ages 30 to 75 years were included. Clinical periodontal parameters (probing depth [PD], clinical attachment loss, bleeding on probing) were recorded, and the participants were divided into four groups after the coronary angiography: group 1: CAD (+) with periodontitis (n = 20), group 2: CAD (+) without periodontitis (n = 20), group 3: CAD (‐) with periodontitis (n = 21), group 4: CAD (‐) without periodontitis (n = 16). Complete blood counts were analyzed regarding the differences and correlations between the investigated parameters.

3 Results

CAD (+) P (+) individuals had significantly higher platelet distribution width (PDW) values than the other groups (P < 0.0125). Positive lower correlations were found between PISA scores and mean platelet volume (MPV, P = 0.021, rho = 0.264), PISA and PDW (P = 0.240, rho = 0.036) in the whole study group; and moderate correlation between PD and red blood cell distribution width (RDW, P = 0.049, rho = 0.445) in CAD (‐) groups with/without periodontitis were found. Age was found to predict CAD with o lower OR (1.17, P < 0.01).

4 Conclusion

The results of the present study highlight some blood parameters (PDW, RDW, and MPV) in CAD patients with/without periodontitis in terms of the relationship between inflammatory diseases and their significant low and moderate correlations with PISA values.     

A comprehensive approach to assigning periodontal prognosis

Aim

The purpose of this retrospective case series study was to evaluate the usefulness and performance of a comprehensive approach to assigning periodontal prognosis by assessing the risk of tooth loss due to periodontal disease (TLPD) and estimate the survival time (ST) of periodontally compromised teeth (PCT).

Material and Methods

The Long‐Term Outcome (LTO) index was utilized to assess the risk of TLPD, at baseline, in 100 patients following periodontal maintenance for a mean 24.7 year (±2.4). A TLPD prediction model was utilized to assign ST to PCT. The performance of the TLPD prediction based on both parameters was assessed.

Results

The mean TLPD rate increased as the LTO index increased (Kruskal–Wallis p < .001). The percentage of TLPD increased as the ST decreased, with significantly differences between the LTO categories <4 and ≥4 for all ST intervals (Mann–Whitney p < .001 to p .021). Only 21% of PCT were lost. This percentage was 58% for teeth assigned the shortest ST and increased to 71% and 88% for these teeth in LTO ≥4 patients.

Conclusions

This approach might be useful to predict TLPD in patients with an initial higher risk of TLPD while it was not useful in patients with lower risk of TLPD.     

Influence of periodontal treatment on subgingival and salivary microbiotas

1 Background

The purpose of this study was to characterize and compare subgingival and salivary microbiotas before and after periodontal treatment to learn if any changes of the subgingival microbiota were reflected in saliva. We tested the hypothesis that salivary levels of specific periopathogens correlate with corresponding subgingival levels before and after periodontal treatment.

2 Methods

Twenty‐five patients with generalized chronic periodontitis completed the study. Stimulated saliva samples and subgingival plaque samples were collected at baseline and 2, 6, and 12 weeks after nonsurgical periodontal therapy. Subgingival and salivary microbiotas were processed by means of the Human Oral Microbe Next Generation Sequencing (HOMINGS) technique and characterized based on relative abundance. Spearman signed rank test was used to test correlation of periopathogens in subgingival and saliva samples.

3 Results

Periodontal treatment resulted in significantly higher relative abundance of Streptococcus, Rothia and Actinomyces in combination with a significant decrease in Porphyromonas and Treponema in subgingival plaque samples. Relative abundance of the overall predominant genera in saliva was not influenced by periodontal treatment. However, there was a positive correlation between samples of subgingival plaque and saliva before and after periodontal treatment (p < 0.0001) with respect to relative abundance of specific periopathogens, such as Porphyromonas gingivalis (r = 0.68), Prevotella intermedia (r = 0.72), Filifactor alocis (r = 0.58), Treponema denticola (r = 0.51), Tannerella forsythia (r = 0.45) and Parvimonas micra (r = 0.45).

4 Conclusions

Subgingival and salivary abundance of periodontal pathogens correlated before and after treatment. Thus, data from this study suggest that periopathogens identified in saliva may be spill‐over from the subgingival microbiota.