Assessment of colour modifications in two different composite resins induced by the influence of chlorhexidine mouthwashes and gels, with and without anti-staining properties: An in vitro study.

OBJECTIVES: Chlorhexidine (CHX)-based products are the most effective chemical agents used in plaque control and oral disinfection. One of their side effects is tooth and restoration staining. For this reason, CHX products with anti-discolouration systems (ADS) have been developed. The aim of this in vitro study was to compare different CHX-based products (gel and mouthwash) with or without ADS in composite colour modification. METHODS: Two hundred specimens were created, 100 of which were made of packable composite and 100 of flowable composite. After 24 h, colour coordinates (L*, a*, b*, C*, h°) were recorded using a spectrophotometer (T0). Then, all samples were subjected to a CHX/tea staining model and immersed in human saliva for 2 min. Composite specimens were divided in 10 groups (N = 20). Control groups (PC, FC) were soaked in distilled water and test groups (PG, PGads, FG, FGads, PM, PMads, FM and FMads) were immersed in CHX-based solutions or brushed with CHX gel. Then the cycle was repeated 6 times, and colour differences (ΔEab and ΔE00 ) were finally calculated. RESULTS: Through flowable composites, FC and FG showed the highest colour differences, respectively ΔEab = 3.48 ± 1.0, ΔE00 = 2.24 ± 0.6 and ΔEab = 2.95 ± 1.3, ΔE00 = 1.53 ± 0.6. In the composite groups instead, PM and PMads showed the highest colour differences, respectively ΔEab = 2.78 ± 1.3, ΔE00 = 1.94 ± 0.8 and ΔEab = 2.71 ± 1.4, ΔE00 = 1.84 ± 0.9. CONCLUSIONS: CHX-containing products are able to cause stains on restorative composite materials. Discolouration is more likely to occur in flowable composites than packable composites, and ADS-containing products cause fewer pigmentations than CHX products without ADS. Packable composites showed more staining after mouthwash treatment, whereas flowable composites underwent higher discolouration after treatment with gels.

Dentin Cross-linking Effect of Carbodiimide After 5 Years.

Carbodiimide (EDC)-based dentin primers preserve hybrid layer (HL) integrity. However, aging >1 y has not been investigated. The present study examined whether the cross-linking effect of EDC was reflected in dentin bond strength, endogenous enzymatic activity, and the chemical profile of the HL after 5-y aging in artificial saliva. Noncarious human third molars (N = 42) were cut to expose middle/deep coronal dentin and treated as follows: group 1, dentin etched with 35% H3PO4, pretreated with a 0.3M aqueous EDC primer for 1 min and restored with XP Bond (Dentsply Sirona); group 2, as in group 1 but without EDC pretreatment; group 3, Clearfil SE Bond (Kuraray-Noritake) primer applied to dentin surface, followed by EDC pretreatment as in group 1 and application of bond; group 4, as in group 3 without EDC pretreatment. After composite buildup, the specimens were cut into sticks or slabs, depending on the experiment. All tests were performed at baseline (T0) and after 5 y of aging (T5) in artificial saliva at 37 °C. Microtensile bond strength (µTBS) was tested at a crosshead speed of 1 mm/min until failure. Endogenous enzymatic activity was investigated with in situ zymography. The chemical profile of HL was determined via Raman spectroscopy. Three-way analysis of variance and post hoc Tukey test were used to analyze µTBS and in situ zymography data (α = 0.05). EDC pretreatment and aging significantly influenced µTBS and in situ zymography results (P < 0.05). Higher bond strength and lower gelatinolytic activity were identified in the EDC-treated groups at T5 (P < 0.05), especially in the etch-and-rinse groups. Raman spectra revealed less defined amide III peaks in control specimens at T5. The EDC cross-linking effect persisted in the HL for 5 y in terms of bond strength, collagen structure preservation, and dentinal enzyme silencing.

Bacteria prevalence in a large Italian population sample: a clinical and microbiological study.

The present study detects those bacterial species which are more strongly related to bleeding on probing, suppuration and smoking in periodontal-affected patients. Nine hundred and fifty-one patients with periodontal diseases were admitted to the Department of Periodontology and Implantology, Dental School of Bologna University where they underwent microbiological tests for six periodontal pathogens (Actinomyces actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, Fusobacterium nucleatum and Tannerella forsythia). Cluster analysis explored the variables that mostly influence both the presence and absolute\relative bacterial load. Logistic regression and multivariate linear regression quantifies these relations. The probability of recovering bacteria belonging to the Red Complex is greater by 25-48% in presence of bleeding on probing. When probing depth is less than 3 mm the probability of presence of each bacterial species is inferior in comparison with depth >6 mm both for Red Complex (of 20-37%), the Orange complex (of 41-61%) and Actinomyces actinomycetemcomitans (46%). Total bacterial cell count increases with pocket depth above all for the Red Complex. As Treponema Denticola and Tannerella Forsytia presence is associated with bleeding on probing and Prevotella intermedia presence with suppuration and smoking. The examination of these three as indicators of periodontitis evolution is suggested.

Role of dentin MMPs in caries progression and bond stability.

Dentin can be described as a biological composite with collagen matrix embedded with nanosized hydroxyapatite mineral crystallites. Matrix metalloproteinases (MMPs) and cysteine cathepsins are families of endopeptidases. Enzymes of both families are present in dentin and collectively capable of degrading virtually all extracellular matrix components. This review describes these enzymes and their presence in dentin, mainly focusing on their role in dentin caries pathogenesis and loss of collagen in the adhesive hybrid layer under composite restorations. MMPs and cysteine cathepsins present in saliva, mineralized dentin, and/or dentinal fluid may affect the dentin caries process at the early phases of demineralization. Changes in collagen and noncollagenous protein structure may participate in observed decreases in mechanical properties of caries-affected dentin and reduce the ability of caries-affected dentin to remineralize. These endogenous enzymes also remain entrapped within the hybrid layer during the resin infiltration process, and the acidic bonding agents themselves (irrespective of whether they are etch-and-rinse or self-etch) can activate these endogenous protease proforms. Since resin impregnation is frequently incomplete, denuded collagen matrices associated with free water (which serves as a collagen cleavage reagent for these endogenous hydrolase enzymes) can be enzymatically disrupted, finally contributing to the degradation of the hybrid layer. There are multiple in vitro and in vivo reports showing that the longevity of the adhesive interface is increased when nonspecific enzyme-inhibiting strategies are used. Different chemicals (i.e., chlorhexidine, galardin, and benzalkonium chloride) or collagen cross-linker agents have been successfully employed as therapeutic primers in the bonding procedure. In addition, the incorporation of enzyme inhibitors (i.e., quaternary ammonium methacrylates) into the resin blends has been recently promoted. This review will describe MMP functions in caries and hybrid layer degradation and explore the potential therapeutic role of MMP inhibitors for the development of improved intervention strategies for MMP-related oral diseases.

Periodontal healing after 'orthodontic extraction' of mandibular third molars: a retrospective cohort study.

In this study we investigated periodontal healing of mandibular second molars following 'orthodontic extraction' of adjacent impacted third molars, under the null hypothesis that there would be no difference in probing pocket depths (PPD) and clinical attachment levels (CAL) at the distal aspect of second molars before and after treatment. A retrospective survey was conducted of 64 patients who consecutively underwent 'orthodontic extraction' of mandibular third molars in close anatomical relationship with the mandibular canal from January 1997 to January 2011. Age, smoking habit, and PPD and CAL at the distal aspect of second molars before and after treatment were recorded. A statistically significant difference was found in PPD and CAL before and after treatment for the overall sample and for the sample classified by age (>25 or ≤25 years), smoking habit (smoker or non-smoker), and type of third molar impaction (horizontal, mesioangular, or vertical). Median PPD and CAL reductions amounted to 6mm and 5mm, respectively. The null hypothesis was rejected and orthodontic extraction proved to be indicated for those impacted mandibular third molars at high risk of a postoperative periodontal defect at the distal aspect of the adjacent second molar.

Carbodiimide inactivation of MMPs and effect on dentin bonding.

The use of protein cross-linking agents during bonding procedures has been recently proposed to improve bond durability. This study aimed to use zymography and in situ zymography techniques to evaluate the ability of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linker to inhibit matrix metalloproteinase (MMP) activity. The hypotheses tested were that: (1) bonding procedures increase dentin gelatinolytic activity and (2) EDC pre-treatment prevents this enzymatic activity. The zymographic assay was performed on protein extracts obtained from dentin powder treated with Optibond FL or Scotchbond 1XT with or without 0.3M EDC pre-treatment. For in situ zymography, adhesive/dentin interfaces were created with the same adhesives applied to acid-etched dentin slabs pre-treated or not with EDC conditioner. Zymograms revealed increased expression of dentin endogenous MMP-2 and -9 after adhesive application, while the use of EDC as a primer inactivated dentin gelatinases. Results of in situ zymograpy showed that hybrid layers of tested adhesives exhibited intense collagenolytic activity, while almost no fluorescence signal was detected when specimens were pre-treated with EDC. The correlative analysis used in this study demonstrated that EDC could contribute to inactivate endogenous dentin MMPs within the hybrid layer created by etch-and-rinse adhesives.

Clinical-radiographic and histological evaluation of two hydroxyapatites in human extraction sockets: a pilot study.

After tooth extraction the healing process involves bone resorption and soft tissue contraction, events that can compromise the ideal implant placement with functional and aesthetic limitations. Following tooth extraction, a socket preservation technique can limit bone resorption. This study evaluated two different types of hydroxyapatite (HA) grafting materials placed into fresh extraction sockets, 6 months after tooth extraction, histologically, clinically and radiographically. Ten extraction sockets from 10 patients were divided in two groups: 5 sockets received a biomimetic HA and 5 received nanocrystalline HA. After 6 months, before implant placement, samples from the grafted area were harvested and evaluated clinically, radiographically and histologically. The percentages of bone, osteoid areas and residual material in the two groups were not statistically different. All samples showed great variability with extensive bone formation and total material resorption or amounts of osteoid tissue that filled the spaces between the residual material particles. The authors did not find any differences between biomimetic and nanocrystalline HA and assume that, within the limits of this study, both these materials could be applied into fresh extraction sockets to limit bone resorption. A control material and a much larger sample size are needed to confirm these findings.

Self-assessed bruxism and phobic symptomatology.

AIM: The aim of this observational study was to compare two samples of patients (identified, from a previous survey carried out in 2007, as self-assessed bruxers and not) on the basis of the presence of anxious/phobic symptoms, general and linked to an oral surgery. METHODS: Forty-three bruxers and 207 non-bruxers were identified; among these last ones a sub-sample of 89 subjects was randomly selected as control and analyzed. The instruments for data collecting were two self-administered psychological questionnaires: STAI-Y1, Phobia Scale by Marks-Sheehan, and supplementary items on specific dental fear/phobia. RESULTS: No significant differences were observed for age, gender and occupation data but interestingly bruxers are significantly more represented among widows/divorced and graduated in comparisons with non-bruxers. Alcohol consumers were more frequent in bruxers than in non-bruxers (55.8% and 12.4%, respectively; P=0.0001). Global anxiety (P=0.02), agoraphobia, claustrophobia, pathophobia, social phobia (P<0.05), are more frequent in bruxers as also a suffocation feeling (P=0.02). The severity of behaviours that aim to avoid the same situations that causes phobias is low and similar in the two groups. CONCLUSION: The involuntary habit of clenching is, in our opinion, reported by the patients who control their anxiety/phobias without avoiding behaviours, increasing the muscular activity at a level relevant to bruxism.

Dental phobia in dentistry patients.

AIM: This study evaluated the presence of current and general phobia and anxiety symptoms in periodontology patients just before treatment in relation to specific dental fears and to general health status and quality of life. METHODS: The study population was all consecutive outpatients attending the Periodontics and Implantology Services, School of Dentistry, University of Bologna, over a 12-month period in 2007. Data collection instruments were psychological questionnaires (State-Trait Anxiety Inventory [STAI]-Y1, Marks-Sheehan Phobia Scale [MSPS], World Health Organization Quality of Life [WHOQOL] short form) plus supplementary items investigating specific dental fears, patient's dental history, and the dentist's clinical assessment of the patient. RESULTS: In all, 250 consecutive patients were recruited. Most (86%) presented with very mild anxiety and phobia symptoms; 13.2% and 13% presented with psychological symptoms of anxiety and phobia, respectively, independently of those subjects with specific dental fears who were significantly younger. The most common dental fears were fear of pain (48.8%) and of receiving an injection (29.9%). The patients' quality of life did not appear to be affected by these fears. CONCLUSIONS: In the dental outpatients seeking treatment for moderate-to-severe dental pathology at a university periodontics and implantology clinic and referring good general health and psychosocial functioning, levels of anxiety and phobia were usually low or absent; but when present, they were independent of ascertained specific dental fears.