Edward P. Allen

Annual review of selected dental literature: Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

This review was conducted to assist the busy dentist in keeping abreast of the latest scientific information regarding the clinical practice of dentistry. Each of the authors, who are considered experts in their disciplines, was asked to peruse the scientific literature in their discipline published in 2016 and review the articles for important information that may affect treatment decisions. Comments on experimental methodology, statistical evaluation, and the overall validity of conclusions are included with many of the reviews. The reviews are not meant to stand alone but are intended to inform the interested reader about what has been discovered in the past year. The readers are then invited to go to the source, if they want more detail.

Periodontal soft tissue root coverage procedures: a consensus report from the AAP Regeneration Workshop.

BACKGROUND Management of gingival recession defects, a common periodontal condition, using root coverage procedures is an important aspect of periodontal regenerative therapy. The goal of the periodontal soft tissue root coverage procedures group was to develop a consensus report based on the accompanying systematic review of root coverage procedures, including priorities for future research and identification of the best evidence available to manage different clinical scenarios. METHODS The group reviewed and discussed the accompanying systematic review, which covered treatment of single-tooth recession defects, multiple-tooth recession defects, and additional focused questions on relevant clinical topics. The consensus group members submitted additional material for consideration by the group in advance and at the time of the meeting. The group also identified priorities for future research. RESULTS All reviewed root coverage procedures provide significant reduction in recession depth, especially for Miller Class I and II recession defects. Subepithelial connective tissue graft (SCTG) procedures provide the best root coverage outcomes. Acellular dermal matrix graft (ADMG) or enamel matrix derivative (EMD) in conjunction with a coronally advanced flap (CAF) can serve as alternatives to autogenous donor tissue. Additional research is needed to do the following: 1) assess the treatment outcomes for multiple-tooth recession defects, oral sites other than maxillary canine and premolar teeth, and Miller Class III and IV defects; 2) assess the role of patient- and site-specific factors on procedure outcomes; and 3) obtain evidence on patient-reported outcomes. CONCLUSIONS Predictable root coverage is possible for single-tooth and multiple-tooth recession defects, with SCTG procedures providing the best root coverage outcomes. Alternatives to SCTG are supported by evidence of varying strength. Additional research is needed on treatment outcomes for specific oral sites. Clinical Recommendation: For Miller Class I and II single-tooth recession defects, SCTG procedures provide the best outcomes, whereas ADMG or EMD in conjunction with CAF may be used as an alternative.

Antioxidants counteract nicotine and promote migration via RacGTP in oral fibroblast cells.

BACKGROUND Smoking is associated with an increased risk of oral health and dental problems. The aim of this study is to address the hypothesis that nicotine impairs wound healing by increasing reactive oxygen species and inhibiting cell migration, and antioxidants (AOs) may counteract nicotine effects. METHODS Primary human gingival fibroblasts (HGFs) and human periodontal ligament (HPDL) fibroblasts were grown to confluence, pretreated with 6 mM nicotine for 2 hours, and treated with AOs in the presence of nicotine. The pure AO compounds ferulic acid (F), phloretin (P), tetrahydrocurcuminoid Cockroft Gault (T), and resveratrol (R) were tested in single, double, or triple combinations (10(-5) M). The migratory behavior at a scratch-wound edge was recorded every 15 minutes for 10 hours by using live-cell imaging. The active form of the Rho-associated protein (Rac) and guanosine triphosphate (GTP) (RacGTP) was immunolabeled and analyzed using confocal microscopy. RESULTS Combinations of double and triple AOs had a greater effect than single AOs on migration rates and Rac activation. The triple combinations PFR and RFT clearly and unambiguously counteracted the effects of nicotine and significantly increased migration rates in HGF and HPDL fibroblast. CONCLUSIONS Treatment with AO combinations clearly counteracted the effects of nicotine by restoring and increasing cell-migration rates. We found the combination of PFR was the most effective in HGFs, whereas, RFT was the most effective combination in HPDL fibroblast. These results clearly demonstrate that PF, RFT, and PFR counteract the negative effects of nicotine on cultured oral fibroblasts via the RacGTP signal-transduction pathway.

Bioactive antioxidant mixtures promote proliferation and migration on human oral fibroblasts.

OBJECTIVE Antioxidants (AOs) are the first line of defence against free radical damage and are critical for maintaining optimum health and well being. The need for AOs becomes even more critical with increased exposure to free radicals generated by pollution, cigarette smoke, drugs, illness, stress and exercise. Antioxidant supplementation is an excellent way of improving free radical protection. The aim of this study was to provide cytotoxicity, proliferation and migration data on the in vitro effects of bioactive AO mixtures on human oral fibroblasts. METHODS Human oral fibroblasts were obtained from human gingival (HGF) and periodontal (HPDL) tissues. Each of these oral fibroblasts was cultured separately in three concentrations of the bioactive pure polyphenol and turmeric derivative mixtures; resveratrol (R), ferulic acid (F), phloretin (P) and tetrahydrocurcuminoids (T); [(RFT), (PFR), and (PFT)]. Cell viability, proliferation, morphology and migratory behaviour were analysed in vitro using high throughput in vitro 96 well plate wound assay. RESULTS RFT decreased (10(-3)M) and increased (10(-5)M) cell number in HGF cells. Three concentrations (10(-3), 10(-4), and 10(-5)M) of PFR and PFT increased DNA synthesis in HGF cells. PFT promoted cell migration but PFR and RFT had no significant change in HGF wound healing rates in a 96 well plate assay monolayer wound. In the HPDL cells, the 10(-4)M concentration of both RFT and PFT increased cell number at 72 h and 96 h whereas the lower concentration 10(-5)M of RFT significantly stimulated cell number at 96 h. PFR (10(-3)M and 10(-5)M) and PFT (10(-3)M) increased DNA synthesis after 48 h treatment in HPDL cells. CONCLUSIONS High and low concentrations (10(-3)-10(-5)M) of these AOs (RFT, PFR) may have beneficial effects on functional mechanisms regulating fibroblast migration and proliferation during gingival healing or periodontal repair.

Periodontal Soft Tissue Root Coverage Procedures: Practical Applications From the AAP Regeneration Workshop

Focused Clinical Question: How should gingival recession (GR) defects be managed based on current evidence? Summary: The purpose of this practical application is to illustrate the management of GR defects with a primary outcome goal of complete root coverage. The consensus in dental literature and among expert clinicians is that root coverage may be attained through the application of different procedures and that outcomes are generally measured by reduced defect depth, gain in clinical attachment, and an increase in keratinized tissue (KT). These procedures may include the use of: 1) subepithelial connective tissue graft (SCTG); 2) coronally advanced flap; 3) free gingival graft; and 4) soft tissue graft substitutes (acellular dermal matrix and xenogeneic collagen matrix materials) and biologics (recombinant human platelet-derived growth factor and enamel matrix derivative). The variability in these techniques revolves around the inclusion or avoidance of a palatal donor graft. The decision as to how to approach a specific clinical GR-type defect should be a combination of considerations relative to the clinicians surgical goals and the patients understanding of the anticipated outcome. The associated systematic review (Chambrone and Tatakis, J Periodontol 2015;86(Suppl.):S8-S51) provides clear evidence that SCTG-based procedures provide the best outcome for mean and complete root coverage, as well as an increase in KT. Patient-reported outcomes, a topic that needs additional research, should be considered in the decision-making process. Conclusion: Based on the available evidence and the illustrated cases included in this practical application, root coverage can be predictably achieved and a successful clinical outcome can be maintained long term.

Bioactive polyphenol antioxidants protect oral fibroblasts from ROS-inducing agents

BACKGROUND Oxidative damage to soft oral tissues may result from exposure to the chemicals or biochemicals found in teeth-whitening products, dental restorations, tobacco, and alcohol. Our working hypothesis is that oral tissues are susceptible to the toxic effects of stressors such as hydrogen peroxide (H(2)O(2)), ethanol (EtOH) and nicotine (Nic), which decrease cell viability/DNA synthesis and elevate reactive oxygen species (ROS). In this study, we investigated specific polyphenols and turmeric derivative antioxidants (AO) in combinations that counteracted the effects of these stressors on cultured oral fibroblast proliferation and ROS production. METHODS Oral fibroblasts were exposed to stressors for 30 min and then treated with 10(-5) M of bioactive AO mixtures [resveratrol, ferulic acid and tetrahydrocurcuminoid (RFT), phloretin, ferulic acid and resveratrol (PFR), phloretin, ferulic acid and tetrahydrocurcuminoid (PFT)] for 24 h. Cell viability and DNA synthesis were monitored using incorporated 3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulphophenyl]-2H-tetrazolium (MTS) and 5-bromo-2-deoxyuridine (BrdU) assays, respectively. Total ROS was measured with dichlorodihydrofluorescein diacetate (H(2)DCFDA). RESULTS Incubation of oral fibroblasts in the stressors for 30 min resulted in a dose-dependent decrease of DNA synthesis and number of viable cells, and an increased total ROS activity. AO treatment counteracted the insults by restoring DNA synthesis levels and cell viability, and decreasing the total ROS activity. CONCLUSION The AO combinations of RFT, PFR and PFT protected the oral fibroblasts from the detrimental effects of H(2)O(2), EtOH and Nic by decreasing total ROS and increasing cell viability and DNA synthesis.

Antioxidant combinations protect oral fibroblasts against metal-induced toxicity §

OBJECTIVE In dentistry, the use of metals in fillings, braces, implants, bridges and other prosthodontic restorations is a common practice. Previous studies revealed that zinc (Zn) and copper (Cu) released from gold alloys, and nickel (Ni) released from nickel-chromium alloys, have a highly cytotoxic effect on fibroblast cell cultures. Our working hypothesis is that oral fibroblasts are susceptible to damage from metals because they elevate reaction oxygen species (ROS). In this study, we investigated specific antioxidant (AO) combinations to determine if they counteract the effects of Cu, Ni and Zn on cultured oral fibroblast proliferation and oxidative damage. METHODS Oral fibroblasts were pretreated with Cu, Ni and Zn for 60min. Thereafter, cells were treated with 10(-5)M combinations of bioactive AO resveratrol (R), ferulic acid (F), phloretin (P) and tetrahydrocurcuminoids (T) (RFT, PFR, PFT) for 24h. Cell viability and DNA synthesis were monitored by 3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium (MTS) and 5-bromo-2-deoxyuridine (BrDU) assays. ROS was measured using the fluorescence response of dichlorodihydrofluorescein diacetate (DCF). RESULTS AO compounds increased recovery of cells exposed to Cu and Zn. Moreover, AO treatment induced DNA synthesis in the presence of the metal stressors. Cu and Ni stimulated production of ROS. PFR treatment decreased ROS in the presence of Cu, Ni and Zn. SIGNIFICANCE These data indicate that pure AOs counteracted the detrimental effects of Cu, Ni, Zn on oral fibroblasts in vitro by increasing cell viability, and DNA synthesis and decreasing ROS activity.

A stab-and-roll biopsy technique to maintain gingival epithelium for desquamative gingivitis.

BACKGROUND Desquamative gingivitis (DG) is a clinical manifestation common to several diseases. It is known that most cases of DG are caused by mucous membrane pemphigoid (MMP), oral lichen planus (OLP), or pemphigus vulgaris (PV). Early recognition and treatment of these diseases can improve the prognosis, but diagnostic delays are common in patients with DG because obtaining a diagnostic biopsy is technically challenging. A biopsy technique designed to maintain the gingival epithelium for patients with DG was developed. The usefulness of this technique is discussed. METHODS This study is based on a retrospective review of 27 DG cases. A stab-and-roll technique was used to obtain gingival tissue. This technique is designed to reduce lateral forces on the epithelium during the procedure and to thereby prevent the inadvertent removal of the epithelium from the biopsy specimen. A total of 52 biopsies comprising 27 for hematoxylin and eosin (H&E)-stained samples and 25 for direct immunofluorescence (DIF) testing were reviewed. RESULTS Fifty-one of the 52 biopsies (98.1%) maintained the epithelium. Only one biopsy (1.9%) showed that the epithelium was totally absent. Therefore, H&E and DIF features of 51 biopsies were analyzed. Definitive diagnoses of the diseases causing DG included MMP (13 cases), PV (eight cases), and OLP (six cases). CONCLUSIONS A diagnostic biopsy was obtained from the gingiva of patients with DG using the stab-and-roll technique. The gingival epithelium was well maintained, and the relationship with the underlying connective tissue was diagnostic. In the future, this stab-and-roll biopsy technique may facilitate early diagnosis and treatment of diseases causing DG.

CROWN MARGINS IN THE ESTHETIC ZONE

In determining where to place a crown margin in the presence of gingival recession, soft tissue grafting would cover the root completely and allow crown margin placement at the new gingival level, thus providing ideal esthetics. However, complete root coverage is not always possible. Complete root coverage is highly predictable only at sites without loss of interdental tissue according to the Miller Classification. If there is loss of interdental tissue fill, only partial root coverage can be expected.

COMMENTARY. Gingival zenith positions and levels of the maxillary anterior dentition.

This article provides some very useful information regarding the gingival form in the esthetic zone. The authors rightfully point out the importance of gingival form in esthetic dentistry as well as the lack of strong evidence supporting the ideal form and relative levels of the gingival margin in the maxillary anterior segment. As the gingival margin provides one border of the tooth, its level and form contribute to the expression of tooth form, the most important feature in dental esthetics.