Mean Lesion Depth Research Articles

Effects of Fluoride on Two Chemical Models of Enamel Demineralization.

This study evaluated the effects of fluoride on subsurface enamel demineralization induced by two commonly used chemical models. Forty-eight enamel blocks were demineralized at pH = 5.0 by an acetate buffer (Group 1), a lactate buffer (Group 2), an acetate buffer with 0.02 ppm fluoride (Group 3) and a lactate buffer with 0.02 ppm fluoride (Group 4) at 25 °C for 3 weeks. The surface destruction percentage (SDP), mineral loss and lesion depth of the blocks were studied using micro-computed tomography. An elemental analysis of the enamel surface was evaluated using an energy-dispersive X-ray spectroscopy. Surface micro-hardness was determined by the Knoop Hardness Test. The mean lesion depth of Groups 1 through 4 were 134.1 ± 27.2 μm, 96.1 ± 16.5 μm, 97.5 ± 22.4 μm and 91.1 ± 16.2 μm, respectively (p < 0.001; group 1 > 2, 3 > 4). The SDPs of groups 1 through 4 were 7.8 ± 8.93%, 0.71 ± 1.6%, 0.36 ± 1.70% and 1.36 ± 2.94% (p < 0.001; group 1 > 2, 3, 4). The fluoride in mean weight percentages of groups 1 through 4 were 1.12 ± 0.24%, 1.10 ± 0.20%, 1.45 ± 0.40% and 1.51 ± 0.51%, respectively (p < 0.001; group 3, 4 > 1, 2). The mean Knoop hardness values of groups 1 through 4 were 27.5 ± 13.3, 39.7 ± 19.3, 73.6 ± 44.2 and 91.0 ± 57.2, respectively (p < 0.001; group 4 > 3 > 2 > 1). The chemical model using an acetate buffer solution created significantly deeper zones of subsurface demineralization on enamel than the lactate buffer solution. An acetate buffer may damage the enamel surface, but the surface damage can be prevented by adding fluoride.

Arresting simulated dentine caries with adjunctive application of silver nitrate solution and sodium fluoride varnish: an in vitro study

The aim of this invitro study was to assess the ability of silver nitrate solution, followed by sodium fluoride varnish, to arrest caries. Dentine slices were prepared and demineralised. Each slice was cut into three specimens for three groups (SF, SDF and W). Specimens of the SF group received topical application of 25% silver nitrate solution followed by 5% sodium fluoride varnish. The SDF group received topical application of 38% silver diamine fluoride solution (positive control). Specimens of the W group received deionised water (negative control). All specimens were subjected to pH cycling for 8days. Dentine surface morphology, crystal characteristics, carious lesion depth and collagen matrix degradation were evaluated by scanning electron microscopy, X-ray diffraction, X-ray microtomography and spectrophotometry with a hydroxyproline assay. Scanning electron microscopy showed that dentine collagen was exposed in group W, but not in groups SF and SDF, while clusters of granular spherical grains were formed in groups SF and SDF. The mean lesion depths (±standard deviation) of groups SF, SDF and W were 128±19, 135±24 and 258±53μm, respectively (SF, SDF<W; P<0.001). The X-ray diffraction analysis indicated that silver chloride was formed in groups SF and SDF. The concentration of hydroxyproline released from the dentine matrix was significantly lower in groups SF and SDF than in group W (P<0.05). The results of this invitro study indicate that the use of silver nitrate solution and sodium fluoride varnish is effective in inhibiting dentine demineralisation and dentine collagen degradation.

Evaluation of demineralisation adjacent to bracket bonded with conventional orthodontic composite, resin modified GIC and nano-ceramic restorative composite

ContextWhite spot lesions form within 4 weeks of bracket placement and 96% patients show its prevalence during fixed treatment. Less than optimal esthetic result is achieved after orthodontic treatment due to demineralization of enamel adjacent to fixed orthodontic appliances in patients with inadequate oral hygiene. AimsAn invitro evaluation of areas of demineralization, before and after subjecting the teeth to caries producing solution for 30 days for three adhesive resins, Transbond XT†, Fuji-Ortho-LC ▪ and Filtek Z 350♦. Settings and design180 sound premolars were divided into 2 broad groups of 90 each. Control group were exposed to artificial saliva solution for 30 days, whereas, experimental group were exposed to both artificial saliva (for 11h) and caries producing solution (for 1h) at the rate of 2 cycles per day for a period of 30 days. These groups were further subdivided into six subgroups of 30 teeth each. After 30 days, for both groups, teeth cusps were ground flat and longitudinal bucco-lingual sections were made with a series 1000 Deluxe Hard tissue microtome, photographed under polarized light microscopy and Motic Image plus software 3.2 was used to measure amount and depth of demineralisation. Depth of demineralization lesion was obtained as an average from three sites within the lesion (gingival, middle and occlusal). ResultsAnalysis of variance (two-way ANOVA) and Tukey's HSD post hoc test indicated significant differences among these groups and materials. Teeth bonded with conventional composite (Transbond XT™† 3M), nanofilled restorative material (Filtek Z 350™♦ 3M) showed more lesion depth when compared with RMGI cement (Fuji-Ortho-LC™ ▪). RMGIC groups had smaller mean lesion depths when compared with composite resin groups. Materials from experimental group showed increased depth of demineralization (p<0.0000) when compared with control group. ConclusionsArea of demineralization in experimental group increased significantly when compared with control group. Least amount of demineralization was seen with RMGIC (Fuji-Ortho-LC ▪) and highest with conventional orthodontic composite (Transbond XT†).

Comparative study of two chemical protocols for creating white spot lesions: An in vitro FluoreCam evaluation.

The aim of the present study was to compare the effectiveness and practicality of two commonly-used protocols for white spot lesion creation. Sound posterior human teeth were sectioned into halves and randomly allocated into two groups (n=20). Using the FluoreCam system, the enamel surfaces were imaged under standardized conditions, and baseline data (area, intensity, and impact) were recorded. Specimens were covered with an acid-resistant polish, leaving a 2×6-mm enamel window. Group 1 was immersed in Queiroz solution (64hours/37°C/pH5 with agitation); Group 2 was immersed in Buskes solution (14days/37°C/pH5 with agitation). The specimens then were imaged again. Within-group changes that occurred over time were evaluated using the Wilcoxon signed-rank test. Between-group differences were analyzed using the Mann-Whitney U-test. Polarized light microscopy (PLM) was used to calculate the mean lesion depth of representative specimens. Each protocol showed significant changes in the surface area, intensity and impact of demineralization over time (P<.05). There were no statistically-significant differences (P=.53, P=.2, P=.74) between the two groups. PLM showed that the mean lesion depths of representative specimens were 51.4 and 73.0μm for groups 1 and 2, respectively. While both protocols produce similar amounts of demineralization, the Queiroz solution is more practical, as it requires less time.

Matrix-induced autologous chondrocyte implantation for treatment of femoral trochlea cartilage injury

To determine the short-term effectiveness of matrix-induced autologous chondrocyte implantation (MACI) for femoral trochlea cartilage injury. A retrospective analysis was performed on the clinical data of 10 patients with femoral trochlea cartilage injury treated with MACI between June 2012 and October 2014. There were 6 males and 4 females, aged from 15 to 48 years (mean, 33 years). The left knee was involved in 3 cases and the right knee in 7 cases. Nine patients had a history of trauma, and 1 case suffered from osteochondritis dissecans. Combined injuries included meniscus injury in 1 case, anterior cruciate ligament injury in 3 cases, and lateral collateral ligament tear in 2 cases. The mean lesion depth was 2.80 mm (range, 2-7 mm), with the mean defect size of 84.85 mm 2 (range, 28.26-153.86 mm 2). The mean duration of definite diagnosis was 14 days (range, 5 days to 3 months). By using arthroscopic biopsy, 200-300 mg healthy articular cartilage at non weight-bearing area of the knee femoral trochlea was collected as a source of seed cells, which were isolated and cultured to prepare MACI membrane. The adhesion activity, growth rate, and mechanical properties of the chondrocytes on the Bio-gide collagen scaffold were evaluated. In addition, the stretch rate, tensile strength, and suture strength of scaffold were tested. MACI membrane was implanted after 2 weeks to 6 months. The visual analogou scale (VAS), Lysholm score, and Tegner movement level score at preoperation and last follow-up were used to assess the function. The MACI membrane was successfully prepared, and the human chondrocytes adhered and grew well on the Bio-gide collagen scaffold. Mechanical test showed that MACI membrane had the stretch rate of 65.27%, the tensile strength of 26.81 MPa, and the suture strength of 6.49 N, indicating good mechanical properties. MACI membrane was successfully implanted. The mean operation time was 58.5 minutes (range, 43-99 minutes), and the mean hospitalization time was 7 days (range, 6-15 days). All incisions healed well. Ten cases were followed up 9 to 16 months (mean, 12 months). Four cases underwent iliac bone graft surgery. The mean healing time was 14 weeks (range, 12-16 weeks). No complications of osteochondrolysis, knee pain, nerve and vascular injury, deep vein thrombosis, and knee adhesion occurred during follow-up. The VAS score, Lysholm score, and Tegner score at last follow-up were significantly improved when compared with preoperative scores ( t=12.060, P=0.000; t=-9.200, P=0.000; t=-14.000, P=0.000). MACI for femoral trochlea cartilage injury has good short-term effectiveness, with less injury and fast function recovery.

In vitro Evaluation of Resin Infiltrant Penetration into White Spot Lesions of Deciduous Molars.

Caries Infiltration is a recent microinvasive restorative technique that permits treatment of non-cavitated demineralized lesions, known as White Spot Lesions (WSL). To evaluate the extent of penetration of a commercially available resin caries-infiltrant into natural WSL occurring in deciduous tooth enamel. Deciduous molars with natural WSL on any smooth surface were selected and sectioned into halves to yield equal control and experimental groups. Therefore, 25 samples in the control group were untreated whereas 25 samples in the experimental group were treated with caries-infiltrant according to the manufacturer's instructions. Samples were then evaluated under cross-polarized light microscope. Lesion Depth (LD) and Penetration Depth (PD) of the caries-infiltrant were measured quantitatively and descriptive statistics were calculated. Mean LD (standard deviation) for all samples (n=50) was 367(±182) μm. Caries-infiltrant demonstrated varying depths of resin penetration into the natural white spot lesions of deciduous molars. Mean PD (standard deviation) was 352 (± 141) μm. Resin-infiltrants can deeply and predictably penetrate enamel porosities in natural WSL in deciduous molars and impede lesion progression and prevent cavitation.

Abstract 303: Optical Tissue Interrogation Technology Incorporated in Irrigated Radiofrequency Ablation Provides Real Time Monitoring of Ablation Lesion Depth

Background: Radiofrequency ablation (RFA) is an effective therapy to treat cardiac arrhythmias. The success rate depends on the location and size of ablation lesions. Electroanatomic Mapping and Contact force-sensing catheters have been shown to enhance the success rates of RFA. We used real-time optical tissue interrogation within the NADH fluorescence (fNADH) range to assess the progression of ablation lesion depth in real time during RF delivery (LuxCath catheter). Methods: Multiple RFA lesions (n=20) were made on an intubated and mechanically ventilated canine (Mongrel) thigh muscles using 7 Fr quadripolar RFA catheter with a 3.5 mm tip open 3.5 mm irrigated electrode incorporating imaging optic. Light was delivered at (360+/-25nm), and fluorescence acquired through fiberoptic bundle at (370-660 nm) by a spectrometer and analyzed in real time. Two types of plots were created for each lesion: intensity (in counts) vs. wavelength (nm), and 465nm peak amplitude (normalized) vs. time (sec). The lesions were made at room temperature with fixed power (15W) and four different durations (10, 20,30,40 sec). After ablation the muscle was stained with 2,3,4-triphenyl-2H-tetrazolium chloride (TTC), bisected at the center and measured the with and depth of the lesion using imageJ software. Results: We performed a total of twenty lesions that were divided into four groups based on the duration of the ablation (10, 20, 30, 40 seconds). The mean lesion depth for those groups was 4.05+/-1.28, 4.99+/-0.9, 6.9+/-1.06 and 7.14+/-1.41 mm, respectively. Lesion depth was correlated with the duration of ablation and fNADH signal intensity with a correlation coefficient of 0.93 and 0.99, respectively. Finally, there was a significant correlation between lesion size and fNADH signal intensity with a correlation coefficient of 0.96. Conclusion: Real-time optical tissue characterization can provide an excellent assessment of lesion progression during RF delivery. Lesion depth was directly correlated to the decrease in fNADH signal intensity. This information may be used to optimize the selection of RF power and RF application time to maximize RF lesion formation and improve the success of ablation procedures.

Abstract CT111: Ablation techniques adapted for low- and middle-income countries

Abstract BACKGROUND: Cervical cancer is a leading cause of cancer-related mortality among women in low- and middle-income countries (LMICs). The World Health Organization recently released guidelines that endorse alternatives to cytology-based screening that will facilitate increased screening coverage and detection of curable cervical cancer precursors. In order to reduce the cancer burden, highly effective screening strategies must be combined with accessible and affordable treatment of cervical intraepithelial neoplasia (CIN). Two point-of-care technologies with the potential to address this treatment gap are the LMIC-adapted CryoPen® Cryosurgical System, with a probe temperature of approximately -60ºC, and the thermocoagulator, with a probe temperature of 100-120ºC, to induce cellular destruction. Since there is scant data on the extent of CIN involvement in an under-screened population, determining mean lesion depth will establish the minimum depth of necrosis (DON) that ablative techniques need to achieve to eradicate CIN. OBJECTIVES: The study aimed to establish the maximum depth of involvement of CIN3 and test whether the LMIC-adapted CryoPen® and thermocoagulator reach the DON established as necessary for eradicating CIN3. METHODS: A convenience sample of 107 cases of CIN3 diagnosed on cold knife cone biopsy were reviewed by a local pathologist at the National Cancer Institute (INEN) of Peru and a U.S. pathologist. Mean depth of involvement was measured in the CIN3 cases and mean DON was measured in the ablated cervical specimens. Ten women undergoing hysterectomy for reasons other than cervical cancer or precancer underwent one of two ablative techniques 12-24 hours prior to surgery at INEN: a single five-minute freeze with the CryoPen® (n = 5) or a single 60-second, 100ºC application of the thermocoagulator (n = 5). Following the hysterectomy, the cervix was separated from the uterus and the anterior and posterior lips were separated and processed. The local pathologist, who was blinded to which ablative technique was used, measured maximum DON in both lips. RESULTS: Mean depth of CIN3 involvement was 2.0mm among 107 cases; 79.4% of cases had a mean depth ?3.0mm, 89.7% had a mean depth ?3.5mm, 93.5% had a mean depth ?4.0mm, and 6.5% had a mean depth ?5.0mm. The maximum DON achieved by the LMIC-adapted CryoPen® was ?3.0 in 80% of cases, ?3.5mm in 80%, ?4.0mm in 80%, ?4.5mm in 40%, and ?5.0mm in 20%. The maximum DON achieved by the thermocoagulator was ?3.0mm in 80% of cases, ?3.5mm in 80%, ?4.0mm in 20%, and ?4.5mm in 20%. The CryoPen® achieved a mean DON of 4.12mm in the anterior lip (range 1.5 - 4.5mm) and 4.08mm in the posterior lip (range 2.8 - 6.0mm). The thermocoagulator achieved a mean DON of 3.54mm in the anterior lip (range 2.2 - 4.5mm) and 3.02mm in the posterior lip (2.0 - 4.1mm). CONCLUSIONS: The pathology review of CIN3 cases showed that 90% of CIN3 would be eradicated if DON reached at least 3.5mm. The mean DON of both the LMIC-adapted CryoPen® and thermocoagulator exceeded 3.5mm. Attempts to improve the range of depths and overall efficacy will be emphasized through ongoing refinement of the devices and remedial training of clinicians providing the treatments. Citation Format: Miriam Cremer, Juan Felix, Luis Taxa, Mauricio Maza, Philip E. Castle, Manuel Alvarez, Jose Jeronimo, Julia Gage. Ablation techniques adapted for low- and middle-income countries. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT111.

The efficiency of child formula dentifrices containing different calcium and phosphate compounds on artificial enamel caries.

Objectives:Fluoride toothpaste has been extensively used to prevent dental caries. However, the risk of fluorosis is concerning, especially in young children. Calcium phosphate has been an effective remineralizing agent and is present in commercial dental products, with no risk of fluorosis to users. This in vitro study aimed to compare the effects of different calcium phosphate compounds and fluoride-containing dentifrices on artificial caries in primary teeth.Materials and Methods:Fifty sound primary incisors were coated with nail varnish, leaving two 1 mm2 windows on the labial surface before immersion in demineralizing solution for 96 hours to produce artificial enamel lesions. Subsequently, one window from each tooth was coated with nail varnish, and all 50 teeth were divided into five groups (n = 10); group A – deionized water; group B – casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) paste (Tooth Mousse); group C – 500 ppm F (Colgate Spiderman®); group D – nonfluoridated toothpaste with triple calcium phosphate (Pureen®); and group E – tricalcium phosphate (TCP). Polarized light microscopy and Image-Pro® Plus software were used to evaluate lesions.Results:After a 7-day pH-cycle, mean lesion depths in groups A, B, C, D, and E had increased by 57.52 ± 10.66%, 33.28 ± 10.16%, 17.04 ± 4.76%, 32.51 ± 8.99%, and 21.76 ± 8.15%, respectively. All data were processed by the Statistical Package for the Social Sciences (version 16.0) software package. Comparison of percentage changes using one-way analysis of variance and Fisher's least squares difference tests at a 95% level of confidence demonstrated that group A was significantly different from the other groups (P < 0.001). Lesions in groups B and D had a significant lesion progression when compared with groups C and E.Conclusions:All toothpastes in this study had the potential to delay the demineralization progression of artificial enamel caries in primary teeth. The fluoride 500 ppm and TCP toothpastes were equal in the deceleration of enamel caries progression and better than CPP–ACP paste and TCP toothpaste.

Pre-Clinical Investigation of a Low-Intensity Collimated Ultrasound System for Pulmonary Vein Isolation in a Porcine Model

ObjectivesThe purpose of this study was to assess the feasibility of pulmonary vein (PV) isolation using low-intensity collimated ultrasound. BackgroundContemporary approaches to PV isolation are limited by the technical complexity of mapping and ablation. We describe a novel approach to left atrial anatomic rendering and PV isolation that aims to overcome some of these limitations by using low-intensity collimated ultrasound (LICU) system, which allows for near real-time geometry creation and automated ablation in a porcine model. MethodsTwenty swine were anesthetized, and the LICU ablation catheter was placed in the left atrium via percutaneous transseptal access. Ultrasound M-mode–based anatomies of the inferior PVs were successfully created, and ablation was performed under automatic robotic control along a user-defined lesion path. One animal was excluded because of device failure. ResultsAll target PVs in the 19 remaining animals were isolated acutely, requiring a mean of 1.6 applications. Ten animals were sacrificed acutely, and the remaining 9 survived for 35 ± 11 days. Of these 9, 1 animal was excluded from analysis because the index lasso position could not be reliably recreated. PVs in 5 of 8 animals remained isolated at sacrifice. Of the 77 total histological sections, 62 lesions (80.5%) were noted to be transmural. Lesions were homogeneous and characterized by coagulative necrosis and fibrous tissue. The mean myocardial thickness was 2.66 ± 1.80 mm, and the mean lesion depth was 4.28 ± 1.97 mm. No extra cardiac or collateral lesions were noted. ConclusionsThis study demonstrates the safety and efficacy of a novel noncontact ultrasound mapping and ablation system to produce continuous transmural lesions that can isolate PVs in a porcine model.

Amount of Calcium Elution and Eroded Lesion Depth in Bovine Enamel Derived from Single Short Time Immersion in Carbonated Soft Drink &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt;

Erosion is one of serious oral health problems among Japanese children. Some dentists argue that brushing just after food/drink intake induces enamel abrasion. Objectives of this study were to evaluate amount of calcium elution from bovine enamel due to single and short immersion into carbonated soft drink, to calculate depth of the eroded lesion, and to determine when to brush teeth after carbonated soft drink intake from the view point of preventing enamel abrasion. Four enamel specimens were made from each of eight bovine teeth. The specimens were covered by quick-cure resin except for enamel surfaces. The four specimens from each bovine tooth were classified into three, six, nine, and 12 minutes immersion (IM3, IM6, IM9, and IM12) groups and immersed separately in five mL of carbonated soft drink. After the immersion, the calcium concentration of the original drink and the drink samples were evaluated using atomic absorption spectrophotometry. The dimension of each enamel specimen was calculated using a planimeter. The amount of eluted calcium per unit area of the enamel specimen into each drink sample was obtained. The depth of the demineralized lesion was obtained by dividing the amount of calcium elution per unit area by the concentration of calcium in enamel and the specific gravity of enamel. The lesion depth of the IM3 group was significantly lower than those in the IM6, IM9, and IM12 groups. The mean lesion depth in the IM12 group which showed the deepest lesion depth was 0.21 μm. As conclusions, the erosive lesion depth due to intake of carbonated soft drink was much shallower than remineralized enamel surface of a white spot lesion which can be repaired in plaque fluid in a short time, suggesting such erosion hardly causes tooth wear, hence it was suggested that brushing teeth just after the intake was recommended.

An in vitro evaluation of the demineralization inhibitory effect of F(-) varnish and casein phosphopeptide-amorphous calcium phosphate on enamel in young permanent teeth.

Aims and Objectives:To determine the demineralization inhibitory potential of fluoride varnish and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and to compare and evaluate the additive effect of fluoride varnish + CPP-ACP.Materials and Methods:Ten healthy premolar teeth that were extracted for orthodontic purposes were collected, and each tooth was longitudinally sectioned buccolingually and mesiodistally into four sections. The teeth were then assigned to four different treatment groups namely fluoride varnish, CPP-ACP, F− varnish followed by CPP-ACP and control. The prepared enamel samples were suspended in an artificial caries challenge for 10 days. The demineralizing inhibitory effects of the groups were recorded using polarized light microscopy.Statistical Analysis Used:Statistical analysis was carried out using analysis of variance and Duncan's multiple range tests.Results:The mean lesion depths of all the groups were Group 1 (fluoride varnish): 104.71, Group 2 (CPP-ACP): 127.09, Group 3: (F− varnish + CPP-ACP): 82.34, Group 4 (control): 146.93.Conclusion:Demineralization inhibitory potential on the additive use of F− varnish and casein phosphopeptide was superior to fluoride varnish or CPP-ACP applied alone on the enamel of young permanent teeth.

Remineralization effect of CPP-ACP and fluoride for white spot lesions in vitro

ObjectivesThis in vitro study compared the remineralization effect on white spot lesions of casein phosphopeptide-amorphous calcium phosphate crème, or CPP-ACP (MI Paste™), 1.1% NaF dentifrice containing 5000ppm of fluoride (ControlRX™), or CPP-ACP crème with 900ppm of fluoride (MI Paste Plus™) with that of a control. MethodsArtificial white spot lesions were created on smooth enamel surfaces of sound molars using a previously reported demineralization model. Specimens were randomly assigned to four treatments (n=35) with a pH-cycling model over 30 days: Control (no treatment); MI Paste (10% CPP-ACP crème); F5000 (1.1% NaF dentifrice); or MI Paste Plus (10% CPP-ACP plus 900ppm fluoride crème). Products were applied following manufacturers’ directions. Changes in mean lesion depth expressed by percent fluorescence loss (ΔF%), and lesion area (mm2) from baseline to after treatment were measured with light-induced fluorescence (QLF). Mean values of each parameter were compared between groups (p<0.05). ResultsThe remineralization pattern for the F5000 group was unique with marked initial remineralization during the first 10 days and little subsequent change. Based on mean lesion area, the F5000 demonstrated greater remineralization than Control, MI Paste and MI Paste Plus groups. Based on mean fluorescence loss, the F5000 group showed improved remineralization relative to MI Paste Plus, but did not differ statistically from the Control at the end of 30 days. ConclusionsThe 1.1% NaF dentifrice demonstrated overall greater remineralization ability than 10% CPP-ACP crème. However, the 1.1% NaF dentifrice was only as effective as the Control to reduce fluorescence loss. Clinical significanceThis study showed that a 1.1% NaF dentifrice (5000ppm) demonstrated greater remineralization ability than the CPP-ACP topical tooth crème and that the addition of fluoride to its formulation seems to enhance remineralization. Saliva also has the ability to exert an important remineralization effect over time.

Inhibitory effect of silver diamine fluoride on dentine demineralisation and collagen degradation

ObjectiveTo investigate the inhibitory effects of 38% silver diamine fluoride (SDF) on demineralised dentine. MethodsHuman dentine blocks were demineralised and allocated to four groups: SF, F, S and W. The blocks in group SF received a topical application of 38% SDF solution (253,900ppm Ag, 44,800ppm F), group F received a 10% sodium fluoride solution (44,800ppm F), group S received a 42% silver nitrate solution (253,900ppm Ag) and group W received deionised water (control). They were subjected to pH cycling using demineralisation solution (pH 5) and remineralisation solution (pH 7) for 8 days. The surface morphology, crystal characteristics, lesion depth and collagen matrix degradation of the specimens were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-CT testing and spectrophotometry with a hydroxyproline assay. ResultsThe surface morphology under SEM showed evident demineralisation with exposed collagen in groups S and W, but not in group SF. Clusters of granular spherical grains were observed in the cross-sections of specimens in groups SF and F. XRD revealed precipitates of silver chloride in groups SF and S. The mean lesion depths (±SD) of groups SF, F, S and W were 182±32μm, 204±26μm, 259±42μm and 265±40μm, respectively (SDF, F<S, W; p<0.01). Groups SF and S had significantly less hydroxyproline liberated from the dentine matrix than groups F and W (p<0.01). ConclusionThe use of 38% SDF inhibited demineralisation and preserved collagen from degradation in demineralised dentine. Clinical significanceSDF application positively influences dentine remineralization.

Capability of an Ultrasonic System to Detect Very Early Caries Lesions on Human Enamel

The purpose of this investigation was to determine if changes in dental enamel with 20 micron depth incipient carious lesion could be detected by an ultrasonic system (US). Natural (unground, unpolished) lesions were produced on human enamel by using a microbial caries model. Specimens with lesions were analyzed using Ultrasonic system (US) as test method, Quantitative-Light Induced Fluorescence (QLF) and Confocal Laser Scanning Microscopy (CLSM) as gold standards. It was found that both ultrasound and QLF could not detect these very early lesions (mean lesion depth: 18.89 µm) created in vitro in the microbial caries model.

Ex vivo Evaluation of Caries Infiltration after Different Application Times in Primary Molars

Low viscosity resins (infiltrants) have been shown to penetrate the lesion body of natural caries lesions almost completely in vitro. However, penetration depths (PD) have not been evaluated in vivo. Therefore, the aim of the present study was to evaluate the penetration of an infiltrant into proximal caries lesions in primary molars after different application times using an ex vivo model. 59 proximal lesions from 34 children were randomly allocated to one of the application times and were infiltrated under clinical conditions for 1, 3, or 5 min. After extraction or exfoliation (n = 48), teeth were sectioned perpendicular to their surfaces and lesion depths (LD) as well as lesion areas (LA) were evaluated using polarized light microscopy. PD and penetration areas (PA) were measured on scanning electron microscopic images. Percentage penetration depth (PPD) and percentage penetration area (PPA) were calculated. The mean (±SD) LD and LA were 596 ± 203 µm and 4.03 ± 2.75 × 10⁵ µm², respectively. PPD ranged from 70 to 80% and PPA from 54 to 60%. Longer application times did not result in significantly deeper or more complete penetration (p > 0.05; ANOVA). In conclusion, proximal caries lesions in primary molars can be infiltrated in vivo to a similar extent as observed previously in vitro. Moreover, 1-min application of the infiltrant led to PD and homogeneity similar to those observed with longer application times up to 5 min.

Enamel erosion depths measured on impressions by a white light interferometer

Objective. To investigate if measurements of the step heights on an impression of eroded enamel surfaces may give reliable values of the etching depths measured directly on the enamel. Materials and methods. Twelve human enamel specimens, with one circular amalgam reference surface in each, were mounted on an epoxy block and ground flat. Baseline images were taken by a White Light Interferometer (WLI) followed by 12 min etch by 0.01 M HCl, pH 2.2. The mean etch depth on each specimen was calculated from three repeated measurements, both on the specimen surfaces and on the silicone polymer impressions of the surfaces. Paired samples t-test was used when comparing the precision of measurements on enamel vs on impression. Results. The mean lesion depths after 12 min etch measured on the 12 enamel surfaces and impressions were 9.9 µm and 10.6 µm, respectively. The direct and indirect measurements correlated well (r2 = 0.95), with 7% higher mean etch depth measured on the impressions (p < 0.05). The reliability of three repeated measurements on enamel and impressions expressed by Intra Class Correlation (ICC) were 0.98 and 0.99, respectively. The average relative precisions of three repeated measurements on the 12 tooth and impression surfaces were (0.5 ± 0.1)% and (0.1 ± 0.02)%, respectively (p < 0.05). The accuracies were 0.4% and 7%, respectively. Conclusion. WLI gave reliable but slightly higher etch depth measurements on impressions compared to enamel surfaces.

Effect of silver and fluoride ions on enamel demineralization: a quantitative study using micro‐computed tomography

This study aimed to investigate the effect of silver and fluoride ions on demineralization of enamel. The coronal parts of 40 extracted sound premolars were prepared into tooth blocks. An unvarnished occlusal surface window (OW) and a flat buccal/lingual surface window (FW) were created for each tooth by covering all other surfaces with an acid-resistant varnish. These blocks were randomly allocated into four groups of 10 blocks each and immersed in respective solutions for 5 minutes: Group 1--2.36 M silver fluoride; Group 2--2.36 M potassium fluoride; Group 3--2.36 M silver nitrate; and Group 4--deionized water. After 7-day immersion in a buffered demineralization solution at pH 4.4, micro-CT scans were taken. Mean lesion depth in the FW area for tooth blocks in AgF, KF, AgNO(3) and control groups were 0 μm, 3.3 ± 10.3 μm, 156.3 ± 30.8 μm, and 173.6 ± 48.6 μm, respectively (p < 0.001). The difference in mean lesion depth between the AgNO(3) and control groups was not statistically significant (p > 0.05). Similar OW and FW lesions were observed in tooth blocks in the AgNO(3) and control groups. Topical application of a 2.36 M fluoride solution can inhibit demineralization of enamel while topical application of silver ions has little effect.

Effects of CPP-ACP with sodium fluoride on inhibition of bovine enamel demineralization: A quantitative assessment using micro-computed tomography

ObjectivesThe present study evaluated the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and CPP-ACP with 900ppm fluoride (CPP-ACPF) pastes on inhibition of enamel demineralization over time, using polychromatic micro-computed tomography (micro-CT). MethodsEnamel blocks were prepared from bovine teeth. The specimens were each treated by one of the following agents, 30min daily for 7 days: deionized water (negative control); CPP-ACP paste; CPP-ACPF paste; and NaF solutions (positive controls) (90, 900, and 9000ppm F). After treatment, the specimens were immersed in a demineralizing solution (pH 4.5) for 24, 72, and 120h. Mean mineral loss (ML) and lesion depth (LD) after each period were determined from mineral density profiles obtained using micro-CT. ResultsML values in all the treatment groups were significantly smaller than those in the control group after 72 and 120h of demineralization (p<0.05, two-way ANOVA and t-test with Bonferroni correction). ML values in CPP-ACPF and NaF solution groups were significantly smaller compared to CPP-ACP group after 72h (p<0.05). LD values in the CPP-ACPF and all the NaF solutions groups were significantly smaller compared to the control group after 120h (p<0.05). The 9000ppm F group showed the lowest nominal ML and LD values. ConclusionsThe application of CPP-ACP or CPP-ACPF pastes to sound enamel surfaces resulted in inhibition of enamel demineralization, and a better effect was noted for the latter paste. Quantitative assessment using polychromatic micro-CT demonstrated to be useful for detecting mineral density changes.

Elemental analysis of the fluoride varnish effects on root caries initiation

Objectives: The usage of fluoride varnish for a moderate to low caries-risk group has not been well validat- ed. This study aimed to evaluate the preventive and therapeutic efficacies of fluoride varnish on the initiat- ed root caries. Materials and Methods: Ten premolars were sectioned into quarters, further divided into two windows, one of which was painted with Fluor Protector (1,000 ppm fluoride, Ivoclar Vivadent). An initial lesion with a well-preserved surface layer was produced by pH cycling. Scanned line analysis using energy dispersive spectrometry determined the weight percentages of Ca and P in the demineralized layer. Scanning Electron microscopy and confocal laser scanning microscopy (CLSM) evaluated the varnish-applied root surfaces. Results: The mean lesion depth (SD) was 12.3 (2.6) μ m (single cycling) and 19.6 (3.8) μ m (double cycling). Double cycling extended the lesion depth, but induced no more mineral loss than single cycling ( p < 0.05). The mean weight percentages of Ca and P between groups with and without varnish were not sig- nificantly different (p < 0.05). A CLSM showed varnish remained within 15 μ m of the surface layer. Conclusions: When a mild acid challenge initiated root tissue demineralization, the application of low-con- centration fluoride varnish did not influence the lesion depth or the mineral composition of the subsurface lesion. (J Kor Acad Cons Dent 2011;36(4):290-299.)