Odontoblast response to cavity preparation with Er:YAG laser in rat molars: an immunohistochemical study

This study aimed to examine the dynamics of odontoblast-lineage cells following cavity preparation with erbium:yttrium–aluminum-garnet (Er:YAG) laser in rat molars. Cavity preparation was made with Er:YAG laser in the mesial surface of the maxillary left first molar of 8-week-old Wistar rats. Contralateral first molar served as unirradiated control. Immediately, 6 and 12 h and 1, 2, 3, 5 and 7 days after the lasing (n = 5, each), specimens were collected and processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin as markers for odontoblast-lineage cells. Cell proliferation assay using bromodeoxyuridine (BrdU) labeling was also performed. Unirradiated teeth showed HSP-25- and nestin-immunoreactivity in odontoblasts. At 6–12 h after irradiation, the odontoblastic layer was disorganized and some of odontoblasts lost the immunoreactivity to HSP-25 and nestin. At 1–2 days, however, HSP-25- and nestin-immunoreactivities in the odontoblast layer showed a noticeable recovery, resulting in the rearrangement of odontoblast-like cells intensely immunoreactive to HSP-25 and nestin at 3–7 days. BrdU-positive cells showed a significant increase at 2 days (P < 0.05 vs. immediate previous time point; one-way analysis of variance and Scheffé post hoc test), peaked at 3 days and then decreased significantly (P < 0.05). It was concluded that under the present experimental condition in rat molars, cavity preparation with Er:YAG laser induced mild and reversible damage to odontoblasts. The reparative process was characterized by the rearrangement of HSP-25- and nestin-immunoreactive odontoblast-like cells, which took place subsequent to the odontoblastic layer disorganization with partial loss of these immunoreactivities.     

Short-term histomorphological effects of Er:YAG laser irradiation to rat coronal dentin-pulp complex

OBJECTIVE: The objective of the study was to examine the morphological changes of neural elements in dentin-pulp complex ultrastructurally after Er:YAG laser irradiation and elucidate the mechanism of pain reduction in cavity ablation. STUDY DESIGN: The Er:YAG laser was applied at occlusal surfaces of upper and lower first molar cusps of 6 rats, and shallow cavities were ablated. The dentin and pulps were examined with light and electron microscopes at 6 hours after the irradiation. Teeth, without laser irradiation, from three rats were used as controls. RESULTS: Disruption of nerve terminals in the dentinal tubules, degeneration of nerve terminals between odontoblasts, and disruption of the myelin sheath in the pulp core were demonstrated with electron microscope. CONCLUSION: Some Er:YAG laser beams could penetrate to deeper areas than ablated area, and damage of nerve fibers and terminals might be a mechanism of pain reduction in cavity ablation with Er:YAG laser.     

Erbium:YAG laser application in caries therapy. Evaluation of patient perception and acceptance

Objectives: In previous studies it has been demonstrated that the Er:YAG laser can be used to prepare cavities efficiently and without thermal damage to the adjacent dental hard and soft tissues. To investigate the patients' response to Er:YAG laser preparation of teeth, a prospective clinical study was performed in five dental hospitals.

Methods: To evaluate patients' perception and response to cavity preparation a direct comparison was made between conventional mechanical preparation and Er:YAG laser preparation of caries in dental hard tissues. Half of the preparations were completed by the laser alone with standardized parameters, with the other half being mechanically prepared. The sequential order of treatment was randomized, and clinical parameters such as depth and location of the cavities were carefully balanced. A three-score evaluation scheme of patient responses was used: comfortable, uncomfortable, very uncomfortable. In addition the patients were asked to decide which was the more uncomfortable form of treatment and the preferred treatment for future caries therapy.

Results: The study included 103 patients with 206 preparations distributed amongst 194 teeth. All teeth gave vital responses (ice test) before and after both types of treatment. The laser treatment was found to be more comfortable than the mechanical treatment, with high statistical significance. During treatment, the need for local anaesthesia was 11% for mechanical preparation compared to 6% during laser application. It was found that 80% of the patients rated the conventional preparation as more uncomfortable than the laser treatment and 82% of the patients indicated that they would prefer the Er:YAG laser preparation for further caries treatment.

Conclusions: The application of the Er:YAG laser system is a more comfortable alternative or adjunctive method to conventional mechanical cavity preparation.     

Er：YAG激光与传统机械去腐制备洞形的体外可行性比较

目的　为Er：YAG激光去除龋损和粘接修复的可行性提供更多的证据。方法　选取南京医科大学附属口腔医院口腔颌面外科门诊拔除的36颗龋坏深及牙本质的磨牙。每个离体牙的龋损都被切成大小相等的两份,分别纳入对照组(机械预备组)和实验组(Er：YAG激光组)。通过测量微拉伸粘接强度(mTBS)、微渗漏深度、观察组织学形貌、微观形态和测量操作时间比较了Er：YAG激光与传统机械法在这些方面的特性。结果　实验组的微拉伸粘接强度高于对照组(n=13,P<0.05),而平均微渗漏深度低于对照组,但差异无统计学意义(n=13,P>0.05)。实验组残留感染牙本质小管少于对照组(n=6,P<0.01)。扫描电镜观察显示,实验组牙本质小管开放、清晰、裸露,而经机械预备的牙本质表面有玷污层(n=4)。实验组的去龋时间明显长于对照组(n=36,P<0.05)。结论　虽然去龋时间较长,但Er：YAG激光用于窝洞预备较传统机械法有更高的微拉伸粘接强度和更少的感染牙本质小管残留。因此,Er：YAG激光是一种合适的临床去龋方法。     

Evaluation of selective caries removal in deciduous teeth by a fluorescence feedback-controlled Er:YAG laser in vivo

This study investigated the ability and efficacy of an Er:YAG laser with a fluorescence feedback system for caries removal in deciduous teeth. Seventy-nine carious lesions were excavated using a fluorescence-controlled Er:YAG laser. Endpoint of treatment was defined by emission of fluorescence from the dentine surface below the pre-selected threshold level of 7 units and the subsequent termination of Er:YAG laser radiation. Dentine samples were obtained from the cavity floor, and viable counts of both Streptococcus mutans and Lactobacilli, expressed as colony forming units (log CFU), were evaluated. Preparation time was recorded to assess efficacy of the treatment procedure. S. mutans and/or Lactobacilli were found in 25 out of 79 lesions. Regarding the counts for S. mutans and Lactobacilli, the median log CFU was 0 (min, 0; max, 5.5) and 0 (min, 0; max, 6), respectively, with 2.4% of all samples yielding more than 100 CFU S. mutans and 4.8% yielding more than 100 CFU Lactobacilli. In 8 out of 79 cases, laser excavated cavities were not judged being caries-free using the conventional tactile criterion for assessing caries tissue. Focussing on these teeth, the median log CFU was 0 (min, 0; max, 0.5) for S. mutans and 0 (min, 0; max, 1.6) for Lactobacilli. The mean time for treatment was 2.3 +/- 1.2 min. Of the children, 93.8% rated the laser treatment to be comfortable. The study indicates that the fluorescence feedback-controlled Er:YAG laser might be an appropriate device for caries removal in children using the suggested threshold level of 7 units.     

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??Er??YAG??2940 nm??laser is in the near-infrared region of the electromagnetic spectrum where it is readily absorbed by water within and between the hydroxyapatite crystals in the tooth. With its many advantages such as painlessness??minimal invasiveness and comfort??Er??YAG laser has been widely used in dental practice since its introduction and is approved by the FDA in 1997 for dental hard tissues. It can effectively cut enamel and dentin without damaging the pulp and reduce the bacteria stayed in the dentin to prevent secondary caries. The surface morphology of cavities has been evaluated by SEM after laser preparation in the primary teeth??and the laser has been shown to be able to remove smear layer. The surfaces were scale-like and uneven with open dentinal tubules without plugging of the tubules. Self-etching system was recommended to be used after irradiation by Er??YAG laser on primary teeth to obtain superior bonding strength and less marginal micro-leakage. When used in caries therapy in children??most children considered Er??YAG laser was more comfortable and painlessness compared with drill treatment. At present??Er??YAG laser can undertake??cavity preparation in permanent or primary teeth??indirect pulp treatment??laser assisted pit and fissure sealants??preventive resin restoration??pulp amputation. Besides that Er??YAG laser can be used on soft tissue such as operculectomy??frenectomy??etc. Finally??laser has proven to offer new treatment opportunities that were not available in the dental field in the past.     

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??Objective    To compare clinical success rates of Er??YAG laser combined with different capping agents for direct pulp capping in primary teeth and evaluate the pain during treatment. Methods    A total of 60 teeth of 60 children between the age of 3 and 5 years were selected for this study. All the samples were randomly assigned to the following 4 groups??n=15???? Er??YAG laser+MTA??the exposed area was sealed with MTA after Er??YAG laser for caries removal and cavity preparation??Er??YAG laser+calcium hydroxide??CH????the treated area was sealed with CH paste after Er??YAG laser for caries removal??dental handpiece+MTA??the exposed pulp was sealed with MTA after dental handpiece for caries removal??dental handpiece+CH??CH was applied after dental handpiece for caries removal. The depth of cavity preparation was recorded while the child felt painful. At the 3-??6-??12-and 24-month recall examiations??the effect was observed by X-ray. Results    The proportion of the depth of cavity preparation??superficial dentin??middle dentin??deep dentin??by handpiece and Er??YAG laser was 50%??40%??10% and 0.67%??20%??79.33%??respectively. The two patterns of cavity preparation revealed significant difference??P < 0.05??. At the 3-??6-??12-month recall examiations??the success rates of the laser groups were higher than the handpiece groups??while they had no significant difference??P > 0.05??. At the 24 months??the success rates of the laser groups were 93.3%. They showed significantly higher success rates than the handpiece groups??P < 0.05??. The success rates of handpiece+MTA and handpiece+CH were 80%??12/15??and 73%??11/15????which did not reveal any significant difference. Conclusion        Er??YAG laser combined with pulp capping agents can be recommended for direct pulp therapy in primary teeth??and Er??YAG laser will result in a slight pain??thus the children will be inclined to accept and complete the treatment. The clinical effect of MTA shows no statistical difference compared with CH.     

Caries-removal effectiveness and minimal-invasiveness potential of caries-excavation techniques: a micro-CT investigation

Objectives

To determine the caries-removal effectiveness (CRE) and minimal-invasiveness potential (MIP) of contemporary caries-removal techniques.

Methods

Carious molars were scanned using micro-CT, after which dentine caries was removed by 9 contemporary caries-removal techniques. The micro-CT was repeated and CRE was determined on basis of the relative volume of residual caries and the mineral density (MD) at the cavity floor. MIP was determined by measuring the cavity size relative to the initial size of the caries lesion.

Results

CRE and MIP varied most for the Er:YAG laser (Kavo) despite its laser-induced fluorescence (LIF) feedback system. Whilst some specimens revealed much residual caries, others showed over-excavation into sound dentine. With the highest Relative Cavity Size, the Er:YAG laser presented the lowest MIP. Rotary/oscillating instruments revealed a more favourable CRE with some tendency towards over-excavation, except for CeraBur (Komet-Brasseler) and Cariex (Kavo) that typically left caries at the cavity floor and cavity walls, respectively. Chemo-mechanical excavation aided by conventional metal excavators (Carisolv, MediTeam; exp. SFC-V and SFC-VIII, 3M-ESPE) combined best CRE with MIP. When however a plastic excavator was used along with exp. SFC-VIII, caries was less completely removed.

Significance

Er:YAG-laser aided by LIF resulted in non-selective caries removal. Rotary/oscillating caries removal may lead to over-excavation, especially when burs are combined with Caries Detector (Kuraray). This risk for over-excavation is reduced when a tungsten-carbide bur is solely used. On the contrary, Cariex (Kavo) and CeraBur showed a tendency for under-preparation. Chemo-mechanical methods were most selective in removing caries, whilst preserving sound tissue.     

Evidence for the existence of intraepithelial nerve endings in the junctional epithelium of rat molars: an immunohistochemical study using protein gene product 9.5 (PGP 9.5) antibody

Innervation of the junctional epithelium was investigated in rat molars by means of immunohistochemistry for protein gene product 9.5 (PGP 9.5) at light and electron microscopic levels. In comparison with our previous study on same tissues using neurofilament protein (NFP)-antibody, the PGP 9.5-immuno-staining further disclosed numerous nerve fibers in the gingiva of rat molars and revealed the existence of a well-developed plexus of PGP 9.5-positive nerve fibers. The interproximal portion also contained numerous nerve fibers.
Observation of horizontal sections revealed a denser innervation toward the inner junctional gingival epithelium than the outer marginal epithelium. The nerve fibers, beaded in appearance and extending from the nerve bundles in the lamina propria, penetrated into the junctional epithelial layer and were distributed throughout the junctional epithelium, with some nerves being located near the epithelial surface. Non-neuronal cells showing PGP 9.5-immunoreactivity were absent in the junctional epithelium. In immunoelectron microscopy, the axoplasm of nerves in the gingiva was filled with electron-dense reaction products of PGP 9.5, except for the cell organellae. The nerve fibers were devoid of Schwann cell investment and terminated among the epithelial cells in the junctional epithelium, frequently beneath the epithelial surface. The intraepithelial nerve endings contained various kinds of vesicles including large-cored ones, supporting the presence of peptidergic innervation shown by previous studies. These findings confirmed the usefulness of PGP 9.5-immunohisto-chemistry for the identification of delicated nerve fibers in dental tissue, and suggested the dense network of nerve fibers that may serve as sensory receptor and other functions in the junctional epithelium.     

Er∶YAG激光在儿童口腔临床中研究与应用

Er∶YAG激光波长2940 nm,可被水和羟基磷灰石充分吸收,可有效切割硬组织,不对牙髓产生损伤,具有杀菌作用,治疗时微创、无痛、舒适。应用Er∶YAG激光进行乳牙备洞后扫描电镜观察牙本质表面无玷污层,起伏不平,牙本质小管清晰。Er∶YAG激光备洞后配合使用自酸蚀粘接系统可获得更高粘接力和减少微渗漏。儿童患者应用Er∶YAG激光去腐备洞与传统方法相比,多数患儿认为激光治疗舒适、无痛或轻微疼痛。目前,Er∶YAG激光在儿童口腔科可进行乳恒牙龋齿备洞治疗、间接牙髓治疗、激光辅助窝沟封闭、预防性树脂充填、牙髓切断术以及软组织小手术（如系带成形术、牙齿助萌术）等。     

Glass ionomer microleakage from preparations by an Er/YAG laser or a high-speed handpiece

OBJECTIVE: The purpose of this study was to compare microleakage of glass ionomer materials (GIC) using two different modes of cavity preparation: a high-speed hand piece and an erbium/yttrium-aluminum-garnet (Er/YAG) laser. METHODS: Eighty caries free permanent molar teeth had class V preparations cut on both the buccal and lingual surfaces. The high-speed hand piece was used to prepare a class V cavity preparation on the buccal surface and an Er/YAG laser was used to prepare a class V cavity preparation on the lingual surface. GIC or resin modified GIC was used as the restorative material. The teeth were thermocycled for 7000 cycles, placed in 2% basic fushin for 24h, sectioned in the center of each restoration, and analyzed under a stereomicroscope. RESULTS: There was no statistical difference in microleakage between the two modes of cavity preparations. The gingival margins had more microleakage than the occlusal margins for both GIC materials and the resin modified GIC showed significantly more leakage than the conventional GIC. CONCLUSIONS: The Er/YAG laser provided an equivalent method of tooth removal when evaluated for microleakage of GIC materials compared to a high-speed hand piece.     

Postnatal development of protein gene product 9.5 and calcitonin gene-related peptide immunoreactive nerve fibres in rat temporomandibular joint disc

Protein gene product 9.5 (PGP 9.5), an immunohistochemical marker of whole nerve fibres, and calcitonin gene-related peptide (CGRP), a marker of thin nerve fibres, were used to elucidate the postnatal development of nerve fibres in rat temporomandibular joint (TMJ) disc. At birth, PGP 9.5-immunoreactive nerve fibres exhibited running towards the central area of the disc, invading by approximately 95 m from the disc attachment. The nerve fibres existing inside the disc became longer during postnatal development. The number of nerve fibres in the disc increased in a progressive manner up to 40 days after birth. CGRP-immunoreactive nerve fibres also presented changes essentially similar to those of PGP 9.5-immunoreactive nerve fibres. However, the proportion of CGRP-immunoreactive nerve fibres to PGP 9.5-immunoreactive ones was approximately 80%, and remained constant up to 40 days after birth. In conclusion, the distribution and the number of nerve fibres are variable during postnatal development, although the ratio of thin nerve fibres remains invariable. It is emphasized that these changes of innervation in the TMJ are associated with the development of masticatory function.     

A histopathological and immunohistochemical study of dental pulp and pulpal nerve fibers in rats after the cavity preparation using Er:YAG laser

The purpose of this study was to investigate histopathological changes in the dental pulp after Er:YAG laser irradiation compared with those after high-speed drill preparation. For evaluation, repair of nerve fibers was observed using an immunohistochemical technique. There was no significant difference between the remaining dentin thickness in either cases. (Mann-Whitney U test). In the Er:YAG laser group a marked fibroblast proliferation and the formation of reparative dentin were observed relative to the high-speed drill group. The time course of the increase and decrease in calcitonin gene-related peptide-immunoreactive fibers in the high-speed drill group was similar to that of previous reports. In the Er:YAG laser group an increase in calcitonin gene-related peptide-immunoreactive fibers was seen earlier than in the high-speed drill group, and 7 days after operation these fibers decreased to control level. The results suggested that the Er:YAG laser leads to pulpal repair earlier than the high-speed drill.     

Immunohistochemical localization of SNARE core proteins in intrapulpal and intradentinal nerve fibers of rat molar teeth

ObjectiveThe present study was designed to elucidate whether three soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) core proteins, syntaxin-1, synaptosomal-associated protein of 25 kDa (SNAP-25), and vesicle-associated membrane protein-2 (VAMP-2), are present in the dental pulp of the rat molar at both the light and electron microscopic levels.DesignImmunohistochemistry for protein gene product 9.5 (PGP 9.5), a pan-neuronal marker, syntaxin-1, SNAP-25, and VAMP-2 was performed on decalcified rat molars for light and electron microscopic analyses. Double-immunolabeling of PGP 9.5 and the SNARE core proteins, as well as combinations of the SNARE core proteins, was also carried out.ResultsPGP 9.5-immunoreactive nerve fibers ran toward the coronal region, ramified at the subodontoblast layer, and formed the subodontoblastic nerve plexus. Most nerve fibers penetrated the predentin and dentin along the dentinal tubules. Most, if not all, nerve fibers displayed immunoreactivity for syntaxin-1, SNAP-25, and VAMP-2. Immunoelectron microscopic analyses confirmed the presence of immunoreactivity for the SNARE core proteins within the intradental axonal elements.ConclusionsThe present findings suggest that, since SNARE core proteins participate in the docking and exocytosis of synaptic vesicles in the central nervous system, they may contribute to vesicle exocytosis from the dental nerve fibers even though there are no apparent synapses.     

Cavity size difference after caries removal by a fluorescence-controlled Er:YAG laser and by conventional bur treatment

To determine the extensions of cavities prepared conventionally by bur or by a fluorescence-controlled Er:YAG laser. Sixty-five human teeth with dentine caries were bisected through the caries lesion and were treated by a fluorescence-controlled Er:YAG laser in a non-contact or a contact mode or by a rotary bur. The specimens were subjected to histological staining and a quantitative evaluation of cavity area (mm²) by computer-assisted alignment. Data were tested for statistical significant differences by the Wilcoxon test (p < 0.05). Twenty-three out of 29 cavities were smaller after caries removal with the non-contact laser compared to the bur. For a threshold level of seven, a cavity size difference of 1.63 (1.86) mm² was calculated compared to a cavity size difference of 5.35 (5.05) mm² after bur excavation. The differences were statistically significant (p = 0.029). No significant differences were observed between the cavity size differences after excavation with the non-contact or the contact laser handpiece. Residual bacteria within the cavity floor were found only in low numbers after all treatments. The present in vitro study indicates that caries removal by a fluorescence-controlled Er:YAG laser using a threshold level of seven resulted in less dentine loss than preparations by a bur.     

Er：YAG 激光龋齿去腐对低龄儿童牙科焦虑症影响的初步观察

临床选取3岁±3月、乳磨牙(牙合)面Ⅱ度龋的患儿20例,随机分成试验组（激光组）和对照组（车针组,n ＝10）,在不使用开口器、束缚带的情况下分别用 Er：YAG 激光和车针去腐。观察患儿初诊、复诊时治疗成功率及畏惧程度。结果显示激光组治疗成功率高于车针组（P ＜0．05）,畏惧程度低于车针组（P ＜0．05）。激光治疗可缓解儿童牙科焦虑,有利于提高临床治疗成功率。     

Fluorescence-controlled Er:YAG laser for caries removal in permanent teeth: a randomized clinical trial

The aim of this randomized clinical study was to compare the efficacy of a fluorescence-controlled erbium-loaded yttrium aluminum garnet (Er:YAG) laser with conventional bur treatment for caries therapy in adults. Twenty-six patients with 102 carious lesions were treated using either the Er:YAG laser, at threshold levels of 7, 8, 9, and 10 [U], or rotary burs. Both techniques were applied to each lesion at separate locations. After treatment, dentine samples were obtained using a carbide bur. The viable counts of Streptococcus mutans (SM) and lactobacilli (LB) [expressed as colony-forming units (log10 CFUs)], treatment time, pain, vibration, and sound intensity were determined. The median numbers of CFUs for SM and LB were not statistically different between laser and bur treatment at threshold levels 7 and 8 [U]. At threshold levels 9 and 10 [U], the median number of CFUs for LB [1.11 (range: 0.00–2.04)] were significantly higher following laser treatment than following bur treatment [0.30 (range: 0.00–0.60)]. The results indicate that treatment with a fluorescence-controlled Er:YAG laser at threshold levels of 7 and 8 removed caries to a level similar to that achieved using conventional bur treatment, with clinically irrelevant amounts of remaining bacteria. Although more time consuming, laser treatment provided higher patient comfort than bur treatment.     

Er：YAG激光在龋病治疗时消除疼痛疗效观察

目的：探讨Er:YAG激光在龋病治疗中的止痛效果。方法：使用Er:YAG激光治疗9例龋齿、观察临床效果及疼痛情况。结果：治疗过程中实验组患者疼痛得分平均为0．22且均未麻醉,而牙钻组疼痛得分平均为1．6,且2例进行麻醉。结论Er:YAG激光可以较好地解决龋齿治疗中的疼痛问题。     

Evaluation of selective caries removal by a fluorescence feedback-controlled Er:YAG laser in vitro

AIM: To establish a fluorescence threshold level that could guide a therapeutic Er:YAG laser through a caries lesion to determine a therapeutic endpoint of caries removal. MATERIALS AND METHODS: A total of 65 extracted human teeth, 35 with dentine caries and 30 healthy, were used for this study. An Er:YAG laser system that emitted at a wavelength of 2.94 microm was used. The laser was equipped with a laser fluorescence feedback system, excitation wavelength 655 nm, to control the irradiation by the Er:YAG laser. The evaluated threshold levels of the fluorescence feedback system were 3, 7, 8, 10, 12, 15 and 20. After treatment the teeth were prepared for histological staining according to the method of Brown and Brenn for the identification of bacteria. The specimens were subjected to a quantitative evaluation of residual bacteria on the treated dentine surface. In addition, the internal fluorescence of dentine and potential fluorescence changes of dentine after laser irradiation were evaluated. Results: About 80% of the irradiated dentine surface showed residual bacteria with threshold levels of 20, 15, 12, and 10. Residual bacteria were not found with threshold levels of 7 and 3. The study revealed a significant increase in dentine fluorescence after laser irradiation. Conclusion: The results of the present in vitro study indicate that a fluorescence threshold level of 7 or 8 units can guide an Er:YAG laser to a complete removal of carious dentine.     

Er：YAG激光预备及酸蚀处理对复合树脂充填体微渗漏的影响

目的 研究Er∶YAG激光备洞及酸蚀处理对复合树脂充填体微渗漏的影响.方法 将40颗离体前磨牙随机平均分为5组制备洞型：A组,高速牙钻预备加酸蚀;B组,Er∶YAG激光预备;C组,Er∶YAG激光预备加酸蚀;D组,高速牙钻预备加Er∶YAG激光蚀刻;E组,高速牙钻预备加Er∶YAG激光蚀刻后酸蚀.所有样本经复合树脂充填后交替放置于5℃与55℃水中各1 min,间隔45 s,共2000个周期进行冷热循环,然后用0.2％亚甲基蓝染色后颊舌向劈开,体视显微镜下观察剖面,记录其微渗漏情况,并进行统计学分析.另选6颗离体前磨牙,随机分为3组,按上述A、B、C三组方法制备,扫描电镜下观察其牙本质界面的结构.结果 在（牙合）壁与龈壁,B组染料渗入严重,到达洞底,微渗漏最大,与其他各组相比有统计学差异（P＜0.05）,A、C、D、E组染料渗入表浅,微渗漏程度之间没有统计学差异（P＞0.05）.扫描电镜下,A组牙本质表面较平整,无玷污层存在,牙本质小管口开放.B组牙本质表面不平整如鳞片状,无玷污层,牙本质小管口开放,直径小于酸蚀组.C组牙本质小管口开放,无玷污层存在,管周牙本质脱矿明显.结论 单纯Er∶YAG激光预备比传统牙钻制备结合酸蚀处理洞型更易发生微渗漏,若Er∶YAG激光预备结合酸蚀剂处理可以使微渗漏程度减小,Er∶YAG激光蚀刻可以达到和酸蚀剂类似的效果.