Effects of desensitizing dentifrices on dentin tubule occlusion and resistance to erosive challenges.

BACKGROUND: Many studies have demonstrated efficacy of casein phosphopeptide (CPP) containing products for dentin tubule occlusion for treatment of dentin sensitivity, but their effectiveness under dynamic erosive challenges remains to be elucidated. The purpose of the present study was to investigate the effectiveness of a desensitizing dentifrice containing CPP in occluding dentin tubules and resisting erosive challenges in comparison to that containing polyvinyl methyl ether/maleic acid (PVM/MA) copolymers. METHODS: A total of 33 dentin discs were prepared from coronal sections of human third molars and divided into 3 groups: a toothpaste containing CPP; a toothpaste containing PVM/MA and submicron silica; and a regular toothpaste (Controls). A soft-bristle toothbrush was used to brush the dentin discs with the dentifrices for 45 strokes in 30 s at a force of approximately 200 g. The brushing cycle was repeated after immersion of the dentin discs in artificial saliva overnight. The dentin discs were then challenged in orange juice for 10 min in an incubator rocking at 120 rpm. Three fields were randomly selected on each dentin disk surface to assess dentin tubule occlusions after each brushing cycle and after orange juice challenge with a 3D laser scanning microscope. Specimen cross sections were examined with a scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS). RESULTS: After the first and second cycles of brushing, dentin tubules were occluded on average by 56.3% and 85.7% in CPP group, 66.2% and 88.1% in PVM/MA group, and 0.0 and 13.0% in the controls, respectively. There were no statistically significant differences in dentin tubule occlusions between the CPP and PVM/MA groups after two cycles of brushing (p>0.05). After dynamic erosive challenges with orange juice, 20.3% of the dentin tubules in the CPP group, 79.1% in the PVM/MA group and none in the control remained occluded (P<0.05). SEM/EDS imaging showed that dentin tubules were blocked with plugs containing dentifrice substances in CPP and PVM/MA groups after treatments, but none in the controls. CONCLUSIONS: Desensitizing dentifrices containing CPP or PVM/MA could effectively occlude dentin tubules after two cycles of brushing. PVM/MA in combination with submicron silicon dioxide exhibited stronger resistance to dynamic erosive challenges by acidic beverages. Inorganic fillers that can enter dentin tubules and resist erosive challenges may be key for desensitizing dentifrices.

Pathogenesis, diagnosis and management of dentin hypersensitivity: an evidence-based overview for dental practitioners.

Though dentin hypersensitivity (DHS) is one of the most common complaints from patients in dental clinics, there are no universally accepted guidelines for differential diagnosis as well as selection of reliable treatment modalities for this condition. The neurosensory mechanisms underlying DHS remain unclear, but fluid movements within exposed dentinal tubules, i.e., the hydrodynamic theory, has been a widely accepted explanation for DHS pain. As several dental conditions have symptoms that mimic DHS at different stages of their progression, diagnosis and treatment of DHS are often confusing, especially for inexperienced dental practitioners. In this paper we provide an up-to-date review on risk factors that play a role in the development and chronicity of DHS and summarize the current principles and strategies for differential diagnosis and management of DHS in dental practices. We will outline the etiology, predisposing factors and the underlying putative mechanisms of DHS, and provide principles and indications for its diagnosis and management. Though desensitization remains to be the first choice for DHS for many dental practitioners and most of desensitizing agents reduce the symptoms of DHS by occluding patent dentinal tubules, the long-term outcome of such treatment is uncertain. With improved understanding of the underlying nociceptive mechanisms of DHS, it is expected that promising novel therapies will emerge and provide more effective relief for patients with DHS.

Effectiveness of resin-based materials against erosive and abrasive enamel wear.

OBJECTIVE: The objective of this study was to test the effectiveness of resin-based materials against erosive enamel wear under erosive and abrasive challenges by orange juice and tooth brushing. METHODS: Fifty enamel specimens from third molars were assigned to five groups: ICON resin infiltration with no etching (ICON-NE), ICON resin infiltration with 15 % HCl etching (ICON-AE), Seal & Protect sealant (S&P), Tetric EvoFlow (TEF), and control. Erosive lesions were first created on enamel, then treated with resin-based materials. Erosive and abrasive challenges by orange juice and tooth brushing were repeated after treatments. Erosive wear of the treated areas was measured with 3D scanning microscopy, and data were analyzed using ANOVA and paired t tests. RESULTS: Treatments with ICON, S&P, and TEF created a protective material coating of 4.5 ± 1.9 µm, 44.3 ± 8.1 µm, and 84.6 ± 15.7 µm in thickness on the lesion surfaces, respectively. After 15 cycles of erosive and abrasive challenges, enamel or material losses were 21.9 ± 2.3 µm for control, 24.5 ± 4.0 µm for ICON-NE, 24.6 ± 7.4 µm for ICON-AE, 11.2 ± 4.1 µm for S&P, and 3.9 ± 1.9 µm for TEF, respectively. The protective coatings were completely lost in the ICON infiltration groups but remained intact in both the S&P and TEF groups after erosive and abrasive challenges. CONCLUSION: In contrast to a resin sealant and a flowable composite, ICON infiltration resin was not effective in protecting enamel surfaces from erosive and abrasive wear. CLINICAL RELEVANCE: Sealant and flowable composite resin may create protective coatings on eroded enamel surfaces and prevent further tissue loss.

Healing outcomes of open versus closed flap procedures for collagen membrane coverage following immediate dental implant placements with simultaneous guided tissue regeneration.

OBJECTIVE: To compare the outcomes of open healing to complete closure for collagen membrane coverage for immediate implant placements with simultaneous guided bone regeneration (GBR) in two retrospective cohorts. METHODS: The subjects included 118 patients who received Bio-Gide® collagen membrane coverage for immediate implant placements and GBR in 20 anterior and 98 posterior teeth. For 58 patients, gingival flaps were released to achieve full coverage of collagen membrane (CC group). For 60 patients, no efforts were made to release the gingival flaps and collagen membrane was left exposed for open healing (OH group). Antibiotics and analgesics were prescribed for 7 days after surgery. The width of crestal open wounds were measured after surgery (W0), and at 1, 2 and 16 weeks (W16). Changes in bone mass were assessed by cone-beam computed tomography after implant placement and again at W16. Gingival and bone tissues over the implant cover screws were harvested and assessed for 16 patients in the OH group at W16. RESULTS: No wound dehiscence occurred in the CC group from W0 to W16. Both the vertical and horizontal bone dimension changes were not significantly different between the OH and CC group. For the OH group, soft tissue was completely healed at W16 when the initial wound widths were ≤6 mm. For those with initial wound widths ≥ 7 mm, the cover screws were exposed in 5/16 patients at W16 but did not affect the final restorations. Tissue staining showed keratinized mucosa and new bone formation above the dental implant in the OH group. CONCLUSION: Open healing achieved healing outcomes similar to those of complete closure for collagen membrane coverage following immediate implant placements. CLINICAL SIGNIFICANCE: For immediate implant placement requiring bone grafting and collagen membrane coverage, it is unnecessary to release the gingival flaps or use tissue grafts to achieve full coverage of the crestal wounds. Open healing with exposed membrane could achieve similar outcomes with less pain and swelling.

Dentin tubule occlusion and erosion protection effects of dentifrice containing bioadhesive PVM/MA copolymers.

OBJECTIVES: To study the effectiveness of a dentifrice containing polyvinylmethyl ether-maleic acid (PVM/MA) copolymer in occluding dentin tubules and investigate the interaction between PVM/MA and type I collagen using surface plasmon resonance (SPR). MATERIALS AND METHODS: Fifteen volunteers brushed dentin discs in situ using dentifrices with and without PVM/MA copolymer in a cross-over design. Dentin tubule occlusion was evaluated after brushing, after overnight saliva challenge in vivo for 12 h and after drinking 250 ml of orange juice. Dentin tubule occlusion and tubule size were compared between the two groups using repeated ANOVA and before and after erosive challenges using paired t tests. SPR using type I collagen as ligand and PVM/MA as analyte was performed to evaluate the binding of the two macromolecules. RESULTS: A median of 91% of dentin tubules were occluded after a single brushing in the PVM/MA group, as compared to 9% in the controls. After overnight saliva challenge and 10 min of erosion by orange juice, a median of 73% of the dentin tubules remained fully occluded in the PVM/MA group as compared to zero in the controls. Dentin tubule size increased after orange juice erosion in the controls but not in the PVM/MA group. SPR study showed that PVM/MA bound readily to collagen molecules in a 4 to 1 ratio. CONCLUSIONS: Dentifrice containing PVM/MA could effectively occlude dentin tubules and prevent dentin erosion. PVM/MA may improve adhesive retention of intra-tubular dentifrice plugs through binding to dentin surface collagen. CLINICAL RELEVANCE: Brushing with dentifrice containing adhesive polymers has preventive effect against dentin erosion and dentin sensitivity.

Clinical practice guidelines for oral health care during pregnancy: a systematic evaluation and summary recommendations for general dental practitioners.

OBJECTIVE: To evaluate and summarize clinical practice guidelines on the prevention, diagnosis, and treatment of dental diseases during pregnancy, and to provide summary recommendations for general dental practitioners involved in the dental care of pregnant women. METHOD AND MATERIALS: Using keywords related to prenatal dental care in combination with guidelines or consensus statements, online databases, websites of professional organizations, and evidence-based practice platforms were searched. Published guidelines or consensus statements that met the inclusion criteria were selected and evaluated with the Appraisal of Guidelines for Research & Evaluation Instrument II (AGREE-II) tool. Key recommendations were summarized and assessed for consistency across the guidelines. RESULTS: A total of 15 guidelines or consensus statement documents for oral health care during pregnancy were found after the initial search, of which 7 documents met the inclusion criteria; these were analyzed with AGREE-II. These guidelines were developed by expert panels and consensus meetings after comprehensive review of the best available evidence, and consistently deliver clear messages that preventive, diagnostic, restorative, and periodontal procedures and tooth extractions are safe throughout pregnancy and effective in improving and maintaining the oral health of mothers and their children. Dental diseases should be treated in a timely manner and dental emergency treatments can be provided at any time during pregnancy. Dental examination and prophylaxis should be conducted every 6 months to maintain the oral health of pregnant women. CONCLUSION: Published clinical guidelines are consistent in delivering clear messages and providing guidance to dental practitioners for timely and effective dental care during pregnancy. Prevention, diagnosis, and treatment of oral diseases are safe throughout the pregnancy.

Effects of mechanical ventilation and portable air cleaner on aerosol removal from dental treatment rooms.

OBJECTIVES: To evaluate the mechanical ventilation rates of dental treatment rooms and assess the effectiveness of aerosol removal by mechanical ventilation and a portable air cleaner (PAC) with a high-efficiency particulate air (HEPA) filter. METHODS: Volumetric airflow were measured to assess air change rate per hour by ventilation (ACHvent). Equivalent ventilation provided by the PAC (ACHpac) was calculated based on its clean air delivery rate. Concentrations of 0.3, 0.5 and 1.0 µm aerosol particles were measured in 10 dental treatment rooms with various ventilation rates at baseline, after 5-min of incense burn, and after 30-min of observation with and without the PAC or ventilation system in operation. Velocities of aerosol removal were assessed by concentration decay constants for the 0.3 µm particles with ventilation alone (Kn) and with ventilation and PAC (Kn+pac), and by times needed to reach 95 % and 100 % removal of accumulated aerosol particles. RESULTS: ACHvent varied from 3 to 45. Kn and Kn+pac were correlated with ACHvent (r = 0.90) and combined ACHtotal (r = 0.81), respectively. Accumulated aerosol particles could not be removed by ventilation alone within 30-min in rooms with ACHvent<15. PAC reduced aerosol accumulation and accelerated aerosol removal, and accumulated aerosols could be completely removed in 4 to 12-min by ventilation combined with PAC. Effectiveness of the PAC was especially prominent in rooms with poor ventilation. Added benefit of PAC in aerosol removal was inversely correlated with ACHvent. CONCLUSIONS: Aerosol accumulation may occur in dental treatment rooms with poor ventilation. Addition of PAC with a HEPA filter significantly reduced aerosol accumulation and accelerated aerosol removal. CLINICAL SIGNIFICANCE: Addition of PAC with a HEPA filter improves aerosol removal in rooms with low ventilation rates.

Platelet-rich plasma in sinus augmentation procedures: a systematic literature review: Part II.

BACKGROUND: Although platelet-rich plasma (PRP) has been extensively studied for over a decade, there are no definitive reports, which prove the benefit of using PRP in sinus augmentation procedures. In addition, no systematic literature review has been done to report the benefit of treatment outcome in patients who received PRP in conjunction with bone/bone substitutes in maxillary sinus augmentation procedures. Therefore, it can be rightly stated that evidence for an adjunctive benefit of using PRP with bone grafts in sinus augmentation procedures is equivocal and inconclusive. AIM: : The objective of this systematic literature review was to examine this literature in determining whether PRP with bone and bone substitutes leads to more rapid and effective bone regeneration clinically, radiographically, and histologically with sinus augmentation procedures and was there any clinical data parallel to animal experiments providing clinical evidence in sinus augmentation procedures? METHODS: A systematic review of randomized clinical trials of at least 6 months duration was conducted comparing PRP and bone/bone substitutes (test group) to bone/bone substitutes (control group) alone. Electronic databases such as MEDLINE and CENTRAL (Cochrane central register of controlled clinical trials) were searched for relevant articles. The reference list of all included articles was searched along with unpublished clinical trials whose abstracts were available. RESULTS: Although, there is a lack of human studies, which show benefit of using PRP in conjunction with bone grafting materials, it can be stated that use of PRP does lead to early regeneration and reduction in healing time of soft and hard tissues. However, no significant statistical or clinical benefit was reported from studies that would satisfy the inclusion criteria. This study answers the question very clearly that at this point of time, there is no human study that strongly supports the benefit of using PRP in sinus augmentation procedures. CONCLUSION: There is a paucity of clinically controlled trials regarding benefits of PRP in sinus augmentation procedures. Theoretically, it seems to have significant beneficial effects on the soft and hard tissue healing; however, the disparity in study design, surgical techniques, and different outcome assessment variables used, makes it difficult to assess the practical benefit of its clinical use. Although no obvious positive effects of PRP on healing of bone graft material in maxillary sinus augmentation procedures were noted, the handling of the particulate bone grafts was improved.

Assessing fluoride treatment and resistance of dental enamel to soft drink erosion in vitro: applications of focus variation 3D scanning microscopy and stylus profilometry.

OBJECTIVES: This study assesses the application of the focus variation 3D microscopy for the evaluation of dental erosion and fluoride treatment for prevention of enamel erosion in vitro. METHODS: Human dental enamel disks were treated with Prevident 5000 (PV, n=15) for 1 week and compared with a reference group (PN, n=15) after orange juice erosion in vitro. A focus variation 3D scanning microscope (IFM) and a stylus type profilometer (SSP) were used to evaluate the erosion depths on enamel. 3D topographic images were taken with vertical resolutions of 0.1 and 0.02 microm. Scratch marks depths from SSP were measured on IFM images. Measurements were compared between the SSP and IFM and between the two study groups. RESULTS: The SSP and IFM measurements of eroded enamel surfaces showed similar trends between the two methods and between the two study groups. The SSP and the IFM measurements were statistically significantly different but correlated with each other. PV group showed consistently lower erosion depth than PN in all profile measures using both SSP and IFM. The stylus tip created scratch marks that were significantly different in depths between the eroded and the reference surfaces in both groups. CONCLUSIONS: The focus variation 3D microscopy is a powerful tool in evaluating surface topography associated with enamel erosion and in assessing the treatment effects of anti-erosive therapies. Topical treatment with Prevident 5000 significantly increased enamel resistance to erosion by orange juice and should be considered as a treatment choice in patients susceptible to acidic dental erosion.

Effects of toothbrushes with tapered and cross angled soft bristle design on dental plaque and gingival inflammation: a randomized and controlled clinical trial.

OBJECTIVE: To investigate the effect of three manual toothbrushes on dental plaque and gingival inflammation. METHODS: The elmex Sensitive Extra Soft (ESES), elmex Sensitive Soft (ESS) and an ADA standard toothbrush (ADAS) were evaluated in a randomized clinical trial. Subjects brushed twice daily in their usual manner. Plaque index (PI), gingival index (GI) and plaque and gingival scores of interproximal spaces (IntPI and IntGI) were evaluated at day 15 and day 30. ANOVA and t-test were used to compare plaque and gingival scores. RESULTS: A total of 84 subjects with mild to moderate gingivitis completed the study. Plaque and gingival scores in ESES and ESS groups decreased from baseline to day 15 and day 30. At day 30, subjects in both ESES and ESS groups had lower plaque and gingival scores than those in the ADAS group (p<0.05). In the ESES group, PI reduced by 13.6% (p<0.0001), and GI by 10.5% (p<0.0001) at day 30 when compared to the baseline scores. In the ESS group, PI reduced by 11.8% (p<0.0001), and GI by 12.0% (p<0.0001) at day 30. The reduction in IntPI and IntGI scores were comparable to those of the overall PI and GI. In contrast, there were no changes in PI, GI, and IntPI and IntGI scores between baseline and the day 15 and day 30 evaluations in the ADAS group. CONCLUSIONS: Both the ESES and ESS toothbrushes are more effective in removing dental plaque and reducing gingival inflammation than the ADA standard toothbrush.

Non-carious cervical lesions imaged by focus variation microscopy.

OBJECTIVE: The aim of this study is to characterize the morphological and histological features of NCCLs in a group of extracted teeth using a focus variation optical microscopic technique that is capable of detecting minute variation in surface topography. METHODS: Twenty three extracted teeth containing NCCLs were collected. Histological features of the surface and longitudinal cross sections were examined using a focus variation microscope (FVM). RESULTS: The sample included 8 teeth with wedge-shaped lesions; the remaining 15 contained saucer-shaped lesions. Wedge-shaped lesions showed obliterated dentinal tubules, parallel furrows and micro-fractures in the surface; longitudinal cross sections revealed subsurface micro-fractures extending toward the pulp chamber. The surfaces of typical saucer-shaped lesions were smooth and relatively featureless. CONCLUSIONS: FVM imaging shows microstructures that are consistent with simultaneous erosion and toothbrush abrasion. Saucer shaped lesions have a smooth featureless surface as well as craters and dimples that could be attributed to uneven acid attack. In wedge-shaped lesions, the presence of scratches and furrows could be attributed to mechanical forces such as tooth brush abrasion. The furrows and in-surface micro-factures of wedge shaped lesions suggest a possible role of tensile stresses but require further investigation. CLINICAL SIGNIFICANCE: NCCLs present in two morphologies, either saucer-shaped or wedge-shaped. Erosion and toothbrush abrasion are important in both types of lesions. Tensile stresses due to occlusal loading may be important in some wedge-shaped lesions. Knowing the etiology of cervical lesions is the key for their prevention.

Protective effects of resin sealant and flowable composite coatings against erosive and abrasive wear of dental hard tissues.

OBJECTIVES: To test the effectiveness of sealant and flowable composite coating on eroded enamel, dentin and cementum under erosive/abrasive challenges in vitro. METHODS: A total of 108 tissue sections (36 each for enamel, dentin and cementum) from third molars were assigned to three groups: Seal & Protect sealant (S&P), Tetric EvoFlow composite (TEF) and control. Erosive/abrasive lesions were created on each specimen by citric acid and brushing with toothpaste. S&P and TEF were applied to the lesions and subjected to erosive/abrasive cycling included 24 cycles of immersion in citric acid (pH 3.6) for 60min, followed by remineralization for 120min and brushing with toothpastes for 600 strokes at 150g. Erosive wear of materials or dental tissues were measured with 3D scanning microscopy and data were analyzed using ANOVA. RESULTS: Treatments with S&P and TEF created a protective material coating of 42.7±17.8µm and 150.8±9.9µm in thickness, respectively. After 24 cycles of erosive/abrasive challenges, tissue losses were -346.9±37.3µm for enamel, -166.5±26.3µm for dentin and -164.7±18.2µm for cementum in untreated controls, as compared to material losses of -24.4±3.3µm for S&P, and -10.8±4.4µm for TEF, respectively. Both S&P and TEF were effective in protecting enamel, dentin and cementum against erosive tooth wear (p<0.01). S&P exhibited faster wear than TEF (p<0.01) and showed spotted peeling in a third of the specimens. TEF remained intact on all three types of dental tissues at the end of the 24 cycles of erosive/abrasive challenges. CONCLUSIONS: A thin coating of flowable composite resin 150µm in thickness may provide long-term protection against erosive/abrasive tooth wear. Resin sealant may provide adequate protection for dental hard tissues in short-term and may require repeated applications if long-term protection is desired.

Impact of a Mandatory Prescription Drug Monitoring Program on Prescription of Opioid Analgesics by Dentists.

Prescription Drug Monitoring Programs (PDMP) are statewide databases that collect data on prescription of controlled substances. New York State mandates prescribers to consult the PDMP registry before prescribing a controlled substance such as opioid analgesics. The effect of mandatory PDMP on opioid drug prescriptions by dentists is not known. This study investigates the impact of mandatory PDMP on frequency and quantity of opioid prescriptions by dentists in a dental urgent care center. Based on the sample size estimate, we collected patient records of a 3-month period before and two consecutive 3-month periods after the mandatory PDMP implementation and analyzed the data on number of visits, treatment types and drug prescriptions using Chi-square tests. For patients who were prescribed pain medications, 452 (30.6%), 190 (14.1%), and 140 (9.6%) received opioid analgesics in the three study periods respectively, signifying a statistically significant reduction in the number of opioid prescriptions after implementation of the mandatory PDMP (p<0.05). Total numbers of prescribed opioid pills in a 3-month period decreased from 5096 to 1120, signifying a 78% reduction in absolute quantity. Prescriptions for non-opioid analgesics acetaminophen increased during the same periods (p<0.05). We conclude that the mandatory PDMP significantly affected the prescription pattern for pain medications by dentists. Such change in prescription pattern represents a shift towards the evidence-based prescription practices for acute postoperative pain.

Training needs for general dentistry residents to place and restore two-implant-retained mandibular overdentures.

Implant therapy is rapidly becoming a standard of care for replacing missing dentition. Predoctoral dental curricula include some training in the implant restorative phase but offer limited exposure to the surgical phase, so it is important for postdoctoral general dentistry residency programs to provide competency training in all phases of implant therapy. The aim of this study was to determine the training needed for general dentistry residents to achieve competence in this area, specifically by defining the number of clinical experiences necessary in both the surgical and prosthetic phases of implant-retained mandibular overdenture construction (IRMOD). Fifteen Advanced Education in General Dentistry (AEGD) residents at one academic dental institution placed two implants in a total of 50 patients with edentulous mandibles and subsequently restored them with IRMOD. The supervising faculty member and the residents evaluated the competency level on a five-point scale after each implant placement and prosthetic case completion. According to the faculty evaluations, the residents achieved surgical competence after placing two implants in four to six cases and prosthetic management competence after restoring two to four cases of IRMOD. All 50 patients were satisfied with the treatment outcomes of IRMOD. This study concluded that general dentistry residents could potentially achieve competence in both the surgical and prosthetic phases of implant therapy while enrolled in an AEGD program.

Two-Year Success Rate of Implant-Retained Mandibular Overdentures by Novice General Dentistry Residents.

The purpose of the present study was to evaluate the clinical success and patient satisfaction when dental implant-retained mandibular overdentures are placed and restored by novice general dentistry residents. A total of 50 subjects who were dissatisfied with their mandibular complete dentures were enrolled in the study. Two dental implants were placed in the anterior mandible between the mental foramina by novice general dentistry residents under the direct supervision of the principal investigator. The resident attached the denture to the implants 3 to 4 months later using locator attachments. The implant success rate was determined by measuring bone loss, mobility, pocket probing depth, and gingival and plaque indices. Subjects were asked to complete a satisfaction questionnaire with the prosthesis at 3 months, 1 year, and 2 years after overdenture delivery. A total of 100 implants were placed in the 50 study subjects. Of these, 2 implants were lost in 1 subject, and 1 subject died due to unrelated causes. Of the 48 remaining subjects, 45 have had their implants restored with overdentures. The subjects' overall satisfaction with fit and ability to chew hard foods with their mandibular overdentures improved significantly (P < .05) following the denture attachment to the dental implants. We conclude that novice general dentistry residents can successfully place mandibular implants and restore them with overdentures under direct supervision, subsequently enhancing the subjects' satisfaction with their mandibular dentures.

Role of clinician's experience and implant design on implant stability. An ex vivo study in artificial soft bones.

OBJECTIVES: Clinical experience in implant placement is important in order to prevent implant failures. However, the implant design affects the primary implant stability (PS) especially in poor quality bones. Therefore, the aim of this study was to compare the effect of clinician surgical experience on PS, when placing different type of implant designs. METHODS: A total of 180 implants (90 parallel walled-P and 90 tapered-T) were placed in freshly slaughtered cow ribs. Bone quality was evaluated by two examiners during surgery and considered as 'type IV' bone. Implants (ø 5 mm, length: 15 mm, Osseotite, BIOMET 3i, Palm Beach Gardens, FL, USA) were placed by three different clinicians (master/I, good/II, non-experienced/III, under direct supervision of a manufacturer representative; 30 implants/group). An independent observer assessed the accuracy of placement by resonance frequency analysis (RFA) with implant stability quotient (ISQ) values. Two-way analysis of variance (ANOVA) and Tukey's post hoc test were used to detect the surgical experience of the clinicians and their interaction and effects of implant design on the PS. RESULTS: All implants were mechanically stable. The mean ISQ values were: 49.57(± 18.49) for the P-implants and 67.07(± 8.79) for the T-implants. The two-way ANOVA showed significant effects of implant design (p < .0001), clinician (p < .0001), and their interaction (p < .0001). The Tukey's multiple comparison test showed significant differences in RFA for the clinician group I/II (p = .015) and highly significant (p < .0001) between I/III and II/III. The P-implants presented (for I, II, and III) mean ISQ values 31.25/49.18/68.17 and the T-implants showed higher ISQ values, 70.15/62.08/68.98, respectively. Clinicians I and II did not show extreme differences for T-implants (p = .016). In contrast, clinician III achieved high ISQ values using P- and T-implants following the exact surgical protocol based on the manufacturer guidelines. T-implants provided high stability for experienced clinicians compared with P-implants. CONCLUSION: T-implants achieved greater PS than the P-implants. All clinicians consistently achieved PS; however, experienced clinicians achieved higher ISQ values with T-implants in poor quality bone.

Fluoride release and anti-erosive effects of dentifrices containing PVM/MA copolymers.

OBJECTIVE: To evaluate fluoride release from dentine discs and study the effects of dentine tubule occlusion and erosion prevention of dentifrices containing fluoride and PVM/MA copolymers in a cycling erosive challenge model. METHODS: Human dentine discs, 15 in each group, were eroded by 1.0% citric acid and treated by ProNamel(®) (PRN, 1450ppm fluoride), Colgate(®) Total Sensitive (CTS, 1100ppm fluoride), a prototype dentifrice containing 5000ppm fluoride and 2% PVM/MA copolymers (PVD) and distilled water (control). Fluoride release from each dentine disc was evaluated every 2h in a 12-h period. For cycling erosive challenges, dentine discs were treated by dentifrice slurries twice daily, followed by immersion in saliva and erosive challenges by orange juice. Dentine discs were stored in saliva between treatment cycles and the cycling erosive challenges were repeated for 15 days. On days 5, 10, and 15, size of dentine tubule openings and level of dentine tubule occlusion were evaluated with a 3D scanning microscope. RESULTS: PVD released more fluorides than other dentifrices in a 12-h period (p<0.05). CTS released more fluorides than PRN at 2, 4, 6, and 8h following a single application (p<0.05). The size of the dentine tubules was smaller and the number of occluded dentine tubules was greater in the CTS and PVD groups than those in the control and PRN groups on day 15 of the erosive challenges. CONCLUSION: Bioadhesive PVM/MA copolymers facilitate fluoride retention and release from dentine discs, and promote dentine tubule occlusion and erosion prevention when combined with hydrated silica particles.

Apical and root canal space sealing abilities of resin and glass ionomer-based root canal obturation systems.

OBJECTIVE: To investigate the apical sealing ability of glass ionomer and resin-based root canal obturation systems in comparison to a conventional vertical compaction of warm guttapercha. METHODS: Forty-five extracted human teeth were randomly assigned into 3 groups of 15 each: a resin-based (EndoRez), a glass ionomer-based (Activ GP), and a conventional gutta-percha plus pulp sealer obturation system (GP/EWT). Apical and root canal space sealing abilities were assessed on five cross-sections 1.0 mm apart starting from the apex. Cross-section images were analysed using a focus-variation 3D scanning microscope and unsealed space was calculated as the percentage of total root canal space occupied by voids and debris. RESULTS: EndoRez had significantly higher rate of apical leakage and deeper dye penetration as compared to GP/EWT and Activ GP. EndoRez group had also more voids and debris (22.5%) in the root canal spaces as compared to GP/EWT (10.5%) and Activ GP (10.8%). Apical leakages occurred not only along the root canal walls, but also along the gutta-percha cones with EndoRez as a result of significant polymerisation shrinkage of the resin sealer. CONCLUSION: Resin-based EndoRez did not form an adequate apical seal of filled root canals. Glass ionomer-based Activ GP was comparable to a vertical compaction of warm guttapercha plus EWT sealer in sealing root canal spaces.

Effects of common beverage colorants on color stability of dental composite resins: the utility of a thermocycling stain challenge model in vitro.

OBJECTIVES: To study the color stability of dental composite resins using a thermocycling stain challenge model accounting for the complex effects of oral environment and tooth brushing. METHODS: Composite resin discs were made from Filtek Supreme Ultra (FiltekSU), TPH3 and Renamel, and subjected to thermocycling challenges in warm coffee (55 °C/pH 5.2) and a cold tea and fruit juice mixtures (5 °C/pH 3.6) for a total of 1000 cycles with 30 seconds dwell time in each solution per cycle. Color was assessed in the CIELAB color space using a Crystaleye dental spectrophotometer before and after thermocycling, and after brushing vigorously for 3 min. The thermocycling stain challenge was repeated for a second 1000 cycles and the discs were brushed again. Color changes were compared among the 3 groups using Kruskal-Wallis test. RESULTS: All 3 groups showed statistically significant color changes after stain challenge, with ΔE* as 5.74 for FiltekSU, 3.21 for TPH3 and 2.52 for Renamel. Color change was more significant in FiltekSU than in TPH3 and Renamel (p<0.05). After brushing, color recovered mostly to its original CIELAB values in TPH3 and Renamel but less so in FiltekSU. The second round of thermocycling stain challenge resulted in color changes in FiltekSU that largely could not be removed by vigorous brushing. CONCLUSIONS: Color stability of FiltekSU is inferior to that of TPH3 and Renamel. The thermocycling stain challenge model can potentially differentiate surface staining that can be removed by brushing from true discoloration of the material that is refractory to oral hygiene procedures.

Patient satisfaction and masticatory efficiency of single implant-retained mandibular overdentures using the stud and magnetic attachments.

OBJECTIVES: To study patient satisfaction and masticatory efficiency of single implant-retained mandibular overdentures using the stud and magnetic attachments in a randomized clinical trial with a crossover design. METHODS: Patients received a single implant placed in the midline of the mandible and either a stud (Locator) or a magnetic (Magfit) attachment, assigned at random. Patient satisfaction, including patient comfort, speech, chewing ability and retention, and masticatory efficiency measured by chewing peanuts, were assessed before and 3 months after attachment insertion. Patient satisfaction and masticatory efficiency were evaluated again 3 months after insertion of the alternate attachment bodies. The outcomes were compared before and after insertion of the attachments and between the two types of attachments using Wilcoxon signed rank tests. RESULTS: Patient overall satisfaction, comfort, speech, chewing ability, and retention improved significantly after insertion of both types of attachment bodies (p<0.05). Masticatory efficiencies also increased in both the Locator and the Magfit groups (p<0.05). There were no statistically significant differences in patient overall satisfaction, comfort, speech, and retention between the two types of attachments (p>0.05). The Locator attachments performed better in perceived chewing ability than the Magfit (p<0.05), but there was no statistically significant difference in masticatory efficiency between the two attachment types (p>0.05). CONCLUSIONS: Clinical outcomes were significantly improved in single implant-retained mandibular overdentures using either the Locator or the Magfit magnetic attachments. There was no difference in masticatory efficiency between the two attachment types.