Scanning electron microscopic observations of human dentine after mechanical caries excavation

OBJECTIVES: The structural integrity and surface characteristics of dentine remaining after caries excavation may be relevant to the subsequent bonding of adhesive restorative materials to the prepared cavity. This in vitro investigation aimed to analyse the different surface characteristics of the dentine cavity floor created after preparation using five different mechanical and chemo-mechanical methods of excavation: hand excavation, slow-speed bur, sono-abrasion, air-abrasion and Carisolv gel. METHODS: Ten cavities were prepared using each excavation method in extracted teeth with occlusal carious lesions. Epoxy resin replicas of the 50 cavities were manufactured from silicone impressions and then analysed using secondary electron scanning electron microscopy (SEM) to ascertain the surface characteristics of the dentine at the cavity floor. RESULTS AND CONCLUSIONS: Results from the 50 cavities examined suggested that each alternative excavation technique produced a different and characteristic dentine surface. Carisolv gel was the only method examined that consistently removed the smear layer during excavation to leave exposed dentine tubules at the end of cavity preparation.     

乳牙化学去龋法的细菌学研究

目的：比较化学去龋法和机械去龋法清除细菌的效果。方法：选取40个龋坏深至牙本质的乳磨牙,中龋或深龋,随机分为化学法去龋组和机械法去龋组,每组20个牙,去龋前后使用无菌挖匙对龋坏牙本质进行取样,分别在4种不同的培养基上进行厌氧培养和计数。结果：两种方法去龋后,除机械法去龋组放线菌外,两种方法其他细菌数显著减少,有统计学意义（P〈0．05）,化学法去龋组比机械法去龋组的总菌数量减少更显著（p〈0．05）。结论：化学去龋法比机械去龋法清除乳牙龋坏细菌效果好。     

Performance of four dentine excavation methods in deciduous teeth

This in vitro study aimed to assess the speed and caries removal effectiveness of four different new and conventional dentine excavation methods. Eighty deciduous molars were assigned to four groups. Teeth were sectioned longitudinally through the lesion centre. Images of one half per tooth were captured by light microscope and confocal laser scanning microscopy (CLSM) to assess the caries extension. The halves were then reassembled and caries removed using round carbide bur (group 1), Er:YAG laser (group 2), hand excavator (group 3) and a polymer bur (group 4). The time needed for the whole excavation in each tooth was registered. After excavation, the halves were photographed by light microscope. Caries extension obtained from CLSM images were superimposed on the post-excavation images, allowing comparison between caries extension and removal. The regions where caries and preparation limits coincided, as well as the areas of over- and underpreparation, were measured. Steel bur was the fastest method, followed by the polymer bur, hand excavator and laser. Steel bur exhibited also the largest overpreparation area, followed by laser, hand excavator and polymer bur. The largest underpreparation area was found using polymer bur, followed by laser, hand excavator and steel bur. Hand excavator presented the longest coincidence line, followed by polymer and steel burs and laser. Overall, hand excavator seemed to be the most suitable method for carious dentine excavation in deciduous teeth, combining good excavation time with effective caries removal.     

伢典化学机械去龋法的扫描电镜研究

目的：利用扫描电镜技术观察伢典和传统车针去龋后窝洞表面的微观形态。方法：选取累及牙本质深层龋坏的离体牙9颗，分为对照组，机械组，伢典组3组，每组3颗。用扫描电镜观察窝洞表面形态。结果：对照组表面有很多碎屑、残渣等，无牙本质小管完整形态。传统车针组的牙本质表面有不规则的颗粒和碎片，有玷污层形成。牙本质小管口堵塞。伢典组的牙本质表面没有玷污层，牙本质小管口清晰可见。结论：伢典能有效去除玷污层。     

Clinical evaluation of Carisolv in the chemico-mechanical removal of carious dentin.

The Chemo-mechanical caries removal technique involves the application of chemical agents, to cause a selective softening of the carious dentine and facilitate removal by gentle excavation. Carisolv is one such new chemical agent used in this minimal invasive technique of carious dentine removal. The present study was, therefore, undertaken to evaluate the efficacy of Carisolv in the chemo-mechanical removal of carious dentine, the time taken for caries removal, the perception of the treatment by the patient, and to evaluate the restorations, radiographically. Accordingly, fifty primary and permanent molars with dentinal carious lesions were excavated using this technique of caries removal. The chemo-mechanical caries removal technique using Carisolv proved to be an effective atraumatic treatment modality with potential interest for use in clinical pediatric dentistry.     

An in vitro investigation of the effect and retention of bioactive glass air-abrasive on sound and carious dentine

OBJECTIVES: To examine the removal rate of sound and carious dentine using bioactive glass air-abrasion and investigate abrasive particle retention of alumina and bioactive glass on abraded dentine. METHODS: Crushed bioactive glass was investigated as an alternative air-abrasive to alumina at air pressures of 138, 413 and 689 kPa in the presence or absence of water. The correlation coefficient between the amount of dentine removed using bioactive glass air-abrasion and the Knoop Hardness Number of dentine was calculated. The comparative retention of bioactive glass (BG) and alumina (AL) abrasive on human dentine blocks were calculated as atomic ratios acquired by spectral analysis between air-abrasive tracers (Si for bioactive glass, and Al for alumina) and Ca. A total of 60 dentine blocks were abraded using Al or BG in 12 groups of 5 using three different pressures in using wet and dry air-abrasion. RESULTS: The amount of dentine removed using bioactive glass air-abrasion had a Somers'D coefficient of 0.65 for the Knoop hardness. Wet air-abrasion caused a significant (p 0.05) decrease in the amount of abrasive retained on the surface for Al air-abrasion at 138 and 413 kPa and BG air-abrasion at 413 and 689 kPa. CONCLUSION: There was a negative correlation between propellant pressure and abrasive retained. Bioglass removed healthy dentine at a higher rate than carious dentine - the difference however, being less than with equivalent alumina air-abrasion, thus making it a potentially more selective instrument for clinical caries excavation.     

Effectiveness and efficiency of chemomechanical carious dentin removal

The aims of this in vitro study were both to determine the time necessary for removal of carious dentin (efficiency) and the Knoop Hardness Number (KHN) of the remaining dentin (effectiveness), using a chemomechanical method (Carisolv) or hand excavation. Thirty human molars were bisected through occlusal carious lesions into two equal halves. Each half was randomly excavated by hand in circular movements with a spoon excavator or using Carisolv gel according to the manufacturer's instructions. The duration of carious dentin removal was recorded. Tooth sections were resin-embedded, ground flat and polished. Dentin KHN was determined at distances of 100, 200, 300, 400 and 500 microm from the cavity floor. Data were analyzed by Wilcoxon's test (alpha= 0.01), ANOVA and Student's t test (alpha= 0.05). The median of the time necessary for chemomechanical excavation was significantly greater than for hand excavation. KHN means (+/- SD) at 100, 200, 300, 400, 500 microm for chemomechanical method were, respectively: 15.6 (+/- 4.96), 18.0 (+/- 6.22), 21.3 (+/- 9.30), 24.3 (+/- 9.25), 28.5 (+/- 11.80); and for hand excavation were: 21.2 (+/- 10.26), 23.4 (+/- 9.49), 28.2 (+/- 11.62), 31.0 (+/- 12.17), 34.3 (+/- 11.95). It may be concluded that hand excavation presented higher efficiency and effectiveness than chemomechanical excavation.     

A confocal microscopic study relating the autofluorescence of carious dentine to its microhardness.

OBJECTIVE: An in-vitro study to examine the correlation between the distribution of the autofluorescent signal emitted from carious dentine (detected using confocal laser scanning microscopy) and its microhardness, within the depths of human dentine lesions. MATERIALS AND METHODS: Twelve carious teeth were sectioned longitudinally, the cut faces marked with a grid reference line system and colour photomicrographs taken. The same samples were imaged using confocal laser-scanning microscopy for autofluorescence and then subjected to microhardness testing using a Knoop microhardness indenter. Adjacent sound dentine was used as a control reference. Digital image superimposition allowed direct comparisons to be made between the colour, autofluorescence and microhardness of each lesion. RESULTS: Sound enamel and dentine did not autofluorescence. Autofluorescence distribution from carious dentine correlated with the highly softened tissue (detected using the Knoop indenter) and terminated at a level superficial to the translucent zone. This zone was still pigmented. Normal, sound dentine hardness levels were found deep to the translucent zone. CONCLUSIONS: A correlation existed between the zone of autofluorescence and carious dentine that was markedly softened by the carious process. These findings highlighted a possibility that the autofluorescence might be used as an in-vitro, objective histological marker for the softened, carious dentine requiring clinical excavation.     

X-Ray Microtomography Study to Validate the Efficacies of Caries Removal in Primary Molars by Hand Excavation and Chemo-Mechanical Technique

Background/Aims: Mechanical removal of carious dentine based on perceived hardness is subjective and tends to be excessively destructive; chemo-mechanical techniques have been proposed as being more objective and conservative. The aims of the present study are to use X-ray microtomography (XMT/micro-CT) to determine the three-dimensional mineral concentration distribution in sound, carious and excavated dentine using hand excavation (HE) and a chemo-mechanical, Carisolv (CS), removal technique for primary molars, and to compare the volume of sound dentine removed in order to validate the efficacies of these two techniques. Methods: Twenty-one primary molars with open carious cavities were hemisected. The carious tissue in one half was then removed by HE and the other by CS. XMT scans were taken before and after caries removal. After alignment, subtracted XMT images from the two scans revealing the tissues removed were generated, from which mineral distributions were determined, and volumes of sound dentine removed by each technique were calculated. Results: It was found that the sound dentine removed by HE and CS techniques accounted for 4.0 and 2.1% of total tissues removed, respectively. The mean cut-off linear attenuation coefficients at 40 keV to which HE and CS excavated to were 1.27 and 1.09 cm(-1), respectively. The corresponding Knoop hardness number for the cut-off for CS was 25 kg·mm(-2). Conclusion: It is concluded that using XMT, CS is validated to be more conservative than HE and preserves a layer of partially demineralised dentine with a mineral concentration >0.97 g·cm(-3).     

A scanning electron microscopic study of different caries removal techniques on human dentin

Scanning electron microscopy (SEM) evaluated the effect of different caries removal techniques on human dentin topography. Thirty-six extracted human carious mandibular molars were randomly assigned to six groups according to caries removal technique. Carious tissue was removed by hand excavation, bur excavation, air-abrasion, laser ablation, chemomechanical methods and sono-abrasion. The remaining dentin surfaces were replicated and gold-coated. The surfaces were examined using SEM and distinct differences in appearance were observed among specimens treated with different caries removal techniques. While hand-excavated, bur-excavated and air-abraded carious dentin surfaces were covered with a residual smear layer, sono-abrasion with patent dentinal tubules completely removed the smear layer. A few patent orifices of dentinal tubules were observed in dentin subjected to laser ablation and chemo-mechanical caries removal.     

In vitro comparison of the efficacy of Carisolv and conventional rotary instrument in caries removal

summary The purpose of this in vitro study was to compare the efficacy of a new chemomechanical caries removal agent, Carisolv^TM (MediTeam AB, Sävedalen, Sweden), with conventional slow‐speed rotary instrument (bur). Fourteen extracted human molar teeth with deep dentine caries and no enamel coverage were selected for the study. Their laser fluorescence values were over 30 (DIAGNOdent^®; KaVo, Biberach, Germany). After the teeth were sectioned through the centre of the carious lesion, one half was removed with conventional drilling (bur); the other half was removed with Carisolv gel. Removal of carious dentine was continued until the lesion was deemed caries‐free by visual and tactile criteria. The preparation time for each caries removal technique was also noted. The two halves of each tooth were fixed in 10% buffered‐formaldehyde for 1 week. They were then decalcified, dehydrated and embedded in paraffin blocks for histological studies. After taking serial sections of 5 μm thickness, sections were mounted on glass slides, deparaffinized, dehydrated and stained with toluidine blue for observation under a light microscope. Each section was examined for the presence of bacteria. Complete removal of caries was achieved in 13 (93%) of 14 conventionally prepared teeth, and 5 (36%) of 14 chemomechanically prepared teeth (P < 0·05). Mean (±SD) time for caries removal was 272 s (±53·3) with Carisolv, and 116 s (±49·4) with drilling. The results of this study suggest that conventional rotary instrument (bur) was more effective than Carisolv in removal of carious tissue and also takes shorter time.     

Determination of residual dentine caries after conventional mechanical and chemomechanical caries removal with Carisolv

The aim of the study was to assess the efficacy of removing dentine caries chemomechanically with Carisolv and with round burs. In 24 extracted permanent teeth each, caries removal with Carisolv or rotating round burs was monitored by checking the hardness of the dentine with a dental explorer and stopped at 12 teeth in each group when either (a) a leather-hard texture was reached or (b) a sharp scratching sound was heard. After embedding and sectioning (400 microm), caries activity of the remaining dentine was assessed using methyl red dye. In microscope images (7x) of the samples, the mean depth of the pink (caries-active, pH<5.5) and yellow (pH>5.5) staining of each carious lesion was calculated. Using a round bur, the depth of caries-active and -inactive lesions was significantly greater when a leather-hard texture (51-58 microm) was reached than when a sharp scratching sound was reached (19-25 microm, t-test, P<0.05). For teeth treated with Carisolv, only the depth of the caries-inactive dentine differed significantly. Regardless of the clinical criterion for caries removal, Carisolv treatment resulted in higher mean depths of caries-active dentine (71-78 microm) than conventional caries removal using the round bur (19-51 microm), while the mean depths of the caries-inactive dentine differed minimally. Thus, caries removal with Carisolv leaves up to a mean of 50 microm more carious dentine than round burs.     

Chemo-mechanical dentine caries removal with Carisolv using a rotating brush.

AIM: The aim of this study was to assess the efficacy of removing dentine caries using carbide burs, Carisolv with hand instruments and Carisolv in combination with a new mechanical excavation method using a rotating brush. METHODS: 36 extracted permanent teeth, with dentine caries, were assigned into 3 groups according to caries removal technique. Caries removal was monitored by checking the properties of the dentine with a dental explorer. After embedding and sectioning (400 microm), remaining caries was assessed by using a caries detector. In microscope images (7x) of the samples, the mean stain depth of the remaining carious tissue per tooth was calculated by AnalySIS computer software. RESULTS: Four to 8 applications (mean time = 10.9 min) of Carisolv were necessary for caries removal with the new method using rotating brushes. The mean thickness of residual dentine caries by this procedure (226 microm, +/- 136) was higher than the one using Carisolv with hand instruments (57 microm, +/- 39) or carbide burs (32 microm, +/- 20). Even in areas with good access to the lesion, an unacceptable amount of residual caries was observed. CONCLUSION: Thus, it seems that Carisolv using rotating brushes does not reach the degree of caries removal reached by additional mechanical abrasion of Carisolv using hand instruments or conventional rotating carbide burs.     

伢典化学与机械去龋法的光镜研究

目的：通过对伢典和传统牙钻去除牙本质龋后的磨片观察，评价伢典的去龋效果。方法：选取龋损已到牙本质的离体牙9个，分为对照组、机械组、伢典组3组，每组3个牙。对照组不处理，机械组用传统牙钻去龋，伢典组用伢典去龋。然后磨制成磨片，在光学显微镜下观察去龋效果。结果：对照组能观察到明显的龋损病理组织结构。伢典组、牙钻组的龋损组织被完全去除。结论：伢典能有效去除龋损组织。     

A practice-based study on stepwise excavation of deep carious lesions in permanent teeth: a 1-year follow-up study

This study reports results from a practice-based study in which deep carious lesions were treated by general dental practitioners using stepwise excavation. The material comprised 94 teeth with deep carious lesions which the clinicians considered would result in pulp perforation if treated by a single and terminal excavation. At therst visit excavation of the peripheral dentine was completed. The outermost part of the central and necrotic dentine was gently removed with a sharp excavator. Standardized assessments of the dentine colour and consistency were made before application of a calcium hydroxide-containing base material and temporarylling. Thenal excavation was completed after a treatment interval ranging from 2 to 19 months, with a median of 6 months. Reassessments of the dentine colour and consistency were made before complete removal of demineralized dentine. The central dentine was signicantly browner and less softened after the sealing period. After removal of the dark-brownish dentine during thenal excavation, the colour and consistency of the exposed central dentine was found to resemble that of the completely excavated peripheral dentine. Onlyve cases resulted in pulp perforation during thenal excavation. The high success rate of teeth surviving thenal treatment without pulp exposure after 1 year of observation shows that it was possible for dentists in general practice to administer and manage the treatment of deep carious lesions, a process which may prolong tooth survival compared with conventional endodontic techniques.     

An in vitro investigation of microtensile bond strengths of two dentine adhesives to caries-affected dentine

OBJECTIVES: To compare the micro-tensile bond strengths of two different adhesive systems (ABF (Clearfil Protect Bond), Kuraray Medical Inc., Tokyo, Japan) and Prime & Bond NT (PBNT, Dentsply, Konstanz, Germany) bonded to caries-affected dentine retained after chemo-mechanical caries removal using Carisolv gel, with that retained after excavation using conventional hand instrumentation. METHOD: Twenty, adult, human extracted carious teeth were used in this split tooth study with bur-cut cavities in sound dentine acting as controls. After clinical caries excavation, the occlusal cavities in each experimental group were restored with either bonding system plus composite. Matchstick-shaped samples through the bond interfaces were sectioned and microtensile bond strengths recorded. Scanning electron microscopy (SEM) was used to ascertain the mode of failure at the restoration-dentine interface. RESULTS: Statistical analysis of the bond strength data showed that for the ABF group, there was no difference in bond strengths between the controls and Carisolv group but these values were significantly higher than those for the hand-excavated samples. PBNT samples showed no significant differences in any of the three test groups, with wider ranging data sets. SEM analysis indicated a variety of failures at the interface including cohesive failures within the caries-affected dentine itself. CONCLUSIONS: From the data generated by this study it could be concluded that microtensile bond strengths of PBNT/composite restorations to caries-affected dentine in clinical cavities were statistically comparable to those to sound dentine. In the ABF/composite restored group (self-etched), the use of conventional hand excavation appeared to weaken the bond strength to the remaining caries-affected dentine. However, the use of Carisolv gel excavation did not compromise bond strengths to caries-affected dentine in either group tested.     

Cultivatable bacteria in dentine after caries excavation using rose-bur or carisolv

To measure the amount of viable bacteria after excavation using conventional rose-bur or the chemo-mechanical Carisolv method, a total of 22 lesions were analyzed (one vital tooth per patient) in this open, controlled and randomized study. Two samples per lesion were taken under aseptic conditions using a rose-bur, one superficially in the caries lesion and one after completed excavation. In in vitro tests more material was collected from the hard caries free dentine as compared to the carious dentine. The samples were incubated on blood agar (aerobically and anaerobically), Rogosa (SL) agar and mitis salivarius (MS) agar. For blood agar (aerobic) both methods resulted in a significant decrease in CFU, for blood agar (anaerobic) and MS agar only the Carisolv method resulted in a significant decrease in CFU and for SL agar neither method resulted in a significant decrease in CFU. Comparing CFU before and after excavation, a considerable reduction of CFU was seen ranging from 10(1) to 10(4). Comparing the excavation methods, there were no significant differences, except in the case of blood agar (aerobic), which showed that Carisolv excavation was more effective in reducing CFU. This study indicated that bacterial sampling collected more material from hard dentine as compared from soft. Remaining bacteria after excavation were low in both groups. The Carisolv method seemed to remove bacteria at least up to and possibly beyond the extent of conventional drilling.     

Chemical and topographical analyses of dentine surfaces after Carisolv treatment

OBJECTIVES: The aim of this study was to characterise the surface chemistry of cavities after chemomechanical caries excavation, and also to measure the surface topography after caries removal with Carisolv or burs, followed by acid etching. METHODS: Fourier transform (FT)-Raman spectroscopy was used to study the relative amounts of organic material and minerals of sound enamel, dentine, and cavities, after caries excavation. Fourier transform infrared spectroscopy (FTIR) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were used for detection of Carisolv substances (i.e. mainly sodium hypochlorite, amino acids, and the gelling agent carboxymethyl cellulose). In total, 19 carious and 11 sound extracted teeth were used for the chemical analyses. Topographic examination of 30 carious extracted teeth was performed with a contact profilometer. RESULTS: The relative amounts of organic material and minerals did not significantly differ between sound dentine and the cavities after caries removal with burs or Carisolv. The FTIR analyses indicated extremely small amounts of Carisolv substances at the cavity surface, but the LA-ICP-MS analyses did not confirm those findings. Furthermore, the topographical parameters did not significantly differ between etched cavities after caries removal using burs or Carisolv. CONCLUSIONS: The chemical and topographical analyses in the present study imply that any differences between the cavities after caries excavation with burs or with Carisolv are insignificant.     

Carisolv在乳磨牙龋治疗中效能的体外研究

目的比较Carisolv和传统手机在乳磨牙龋病治疗中去龋后窝洞表面微形态、充填后微渗漏情况及微拉伸粘接强度。方法 96颗离体龋坏乳磨牙,随机分成2组,分别用Carisolv和手机去龋,用扫描电镜观察窝洞表面形态,微渗漏发生情况,并测试微拉伸粘接强度。结果 Carisolv去龋组的牙本质表面牙本质小管口清晰可见,充填后微渗漏的发生与手机去龋组有统计学意义（Z=4.831,P〈0.05）,2组充填后的牙本质粘接强度差异无统计学意义（t=1.89,P〉0.05）。结论 Carisolv能有效去除玷污层,显著减少术后微渗漏的发生,对牙本质粘接强度无显著影响。     

Microhardness and Ca:P ratio of carious and Carisolv treated caries-affected dentine using an ultra-micro-indentation system and energy dispersive analysis of x-rays--a pilot study

BACKGROUND: This study aimed to evaluate microhardness and chemical analysis of carious and caries-affected dentine. The hypothesis tested was that calcium:phosphorous (Ca:P) ratios correlate with microhardness values. METHODS: Four carious human third molars were sectioned through the caries lesion in the mesiodistal longitudinal plane. One half of each lesion underwent carious dentine removal using Carisolv gel. The cut surfaces were polished, microhardness tested using an Ultra-Micro-Indentation System (UMIS) and elemental analysis performed using energy dispersive analysis of x-rays (EDAX). RESULTS: The microhardness of carious dentine decreased gradually towards the cavity floor, but that for caries-affected dentine showed more variation with depth, having a mean hardness of (0.63 +/- 0.18) GPa. Ca:P ratios of carious dentine varied among the four specimens. The mean Ca:P ratio of caries-affected dentine was 1:2.03 +/- 0.08. The hypothesis was accepted for active lesions. CONCLUSIONS: The use of Carisolv to excavate carious tissue can be as effective as rotary instrumentation.