成骨诱导剂对拔牙创愈合的影响

目的 探讨以明胶海绵为载体,地塞米松、维生素C和β-甘油磷酸钠组成的成骨诱导剂对拔牙创愈合和牙槽嵴形态改建的影响。方法选用50只家兔,拔除双侧上颌第一前磨牙,右侧拔牙创内填入载有成骨诱导剂的明胶海绵,作为实验侧;左侧填入空载明胶海绵,作为对照侧。拔牙后第1、2、4、8、12周各处死10只动物,取双侧牙槽骨标本,拍摄X线片,并测量骨缺损区新骨密度;用组织学方法评价拔牙创愈合情况;并于12周时,测量拔牙区牙槽嵴高度吸收值。结果X线片骨密度测量显示：术后2、4、8、12周,实验侧骨密度值均高于对照侧,差异有统计学意义（P<0.01）。组织学检查显示：实验侧拔牙创内成骨现象较对照侧早,成骨细胞分化和增殖更活跃。
12周时实验侧牙槽嵴高度吸收值小于对照侧,差异有统计学意义（P<0.01）。结论 由地塞米松、β-甘油磷酸钠和维生素C组成的成骨诱导剂能促进拔牙创愈合,加速成骨和骨改建。     

Sodium hyaluronate accelerates the healing process in tooth sockets of rats

Objective

In this study we evaluated the effects of sodium hyaluronate (HY) in the healing process of tooth sockets of rats.

Design

Immediately after the extraction of the upper first molars of male Holtzman rats, right sockets were treated with 1% HY gel (∼0.1 ml), while left sockets were used as control (blood clot). The animals were sacrificed at 2, 7, and 21 days after tooth extraction and upper maxillaries processed for histological and morphometric analysis of the apical and medium thirds of the sockets. Carbopol, an inert gel, was used to evaluate the mechanical effect of gel injection into sockets. Expression of bone morphogenetic protein-2 (BMP-2) and osteopontin (OPN) was determined by immunohistochemistry at 1, 2, 3, 4, 5, and 7 days after tooth extraction.

Results

Histological analysis showed that HY treatment induced earlier trabecular bone deposition resulting in a bone matrix more organized at 7 and 21 days after tooth extraction. Also, HY elicited significant increase in the amount of bone trabeculaes at 7 and 21 days after tooth extraction (percentage of trabecular bone area at 7 days: 13.21 ± 4.66% vs. 2.58 ± 1.36% in the apical third of control sockets) and in the vessels counting at 7 days. Conversely, the number of cell nuclei was decreased in HY-treated sockets. Additionally, expression of BMP-2 and OPN was enhanced in HY-treated sockets compared with control sockets.

Conclusions

These findings suggest that HY accelerates the healing process in tooth sockets of rats stimulating the expression of osteogenic proteins.     

Bone healing after dental extractions in irradiated patients: a pilot study on a novel technique for volume assessment of healing tooth sockets

The aim of this study was to evaluate longitudinally the bone-healing process by measuring volumetric changes of the extraction sockets in head and neck cancer patients undergoing radiotherapy after tooth extraction. A total group of 15 patients (nine males, six females) undergoing tooth extraction at the Department of Periodontology (University Hospital KULeuven) were enrolled after giving informed consent. In seven patients, teeth presenting a risk for complications and eventual radionecrosis were extracted prior to the radiotherapeutical procedure. Monitoring of bone healing was performed by evaluating the volumetric changes of the alveoli by cone beam CT scanning (CBCT) at extraction and after 3 and 6 months. In parallel, a similar longitudinal evaluation of extraction sites was done in a control group of eight patients. Within this pilot-study, a total of 15 healing extraction sockets were evaluated and followed up. There was a significant difference in volumetric fill up of extraction sockets in test group vs. control group at three (37.1 ± 7.9%) vs. (54.6 ± 4.0%) and 6 months (47.2 ± 8.8%) vs. (70.0 ± 7.3%), respectively. The present pilot study demonstrated the clinical usefulness of CBCT for evaluation of extraction socket healing. The study objectively demonstrates the delayed bone healing after tooth extraction in irradiated head and neck cancer patients. Considering the limitations of this pilot study, a potential effect of radiotherapy on further jaw bone healing after pre-therapeutic tooth extractions should be further explored.     

大鼠同种异体骨髓间充质干细胞联合Bio-Oss骨粉-bFGF复合物促进拔牙窝愈合的micro-CT研究

目的:观察以Bio-Oss骨粉bFGF支架联合大鼠骨髓间充质干细胞(BMSCs)植入大鼠拔牙窝后在牙槽窝愈合过程中对牙槽骨微结构的影响.方法:取3周龄SD大鼠股骨全骨髓,自然贴壁分离BMSCs.选取36只6周龄SD大鼠,拔除上颌后牙,立即植入不同材料.按植入材料分为4组,即复合物组植入BMSCs联合Bio-Oss骨粉b...     

辛伐他汀对大鼠牙移动后牙周组织中骨形成蛋白2表达的影响

目的 明确全身给予辛伐他汀对大鼠牙齿移动后复发的影响,探讨辛伐他汀促进牙齿稳定的作用机制.方法 选用32只雄性Wistar大鼠,随机分成4组:对照组(0.9%NaCl)、低剂量组(2.5 mg·kg-1 辛伐他汀)、中剂量组(5.0 mg·kg-1 辛伐他汀)、高剂量组(10.0 mg·kg-1辛伐他汀),牵引其上颌第一磨牙向近中移动,持续21 d.实验组在加力装置去除前1 d开始,腹膜下注射辛伐他汀,阴性对照组注射生理盐水,每天1次,连续4周.分别在加力装置去除时及其后1、4周,测量上颌第一、第二磨牙间距离.取上颌第一磨牙及其牙周组织行组织学切片,HE染色及骨形成蛋白2(BMP-2)免疫组织化学染色,并进行图像分析和统计.结果 ①低、中、高剂量组大鼠牙齿移动复发距离均小于对照组(P＜0.05)、复发率明显低于对照组(P＜0.01),且剂量越小复发程度越小,低剂量组复发率最低(1、4周的复发率分别为26.81%、53.38%);②牙周组织中BMP-2表达量,低、中、高剂量组均高于对照组,差异有统计学意义(P＜0.001),低剂量组灰度积分增高最明显(P＜0.001);牙周组织中BMP-2表达,张力区略高于压力区,差异无统计学意义(P＞0.05).结论 在正畸牙齿移动后复发的过程中,辛伐他汀能有效抑制实验性牙移动后牙齿复发的程度,低剂量的辛伐他汀效果最明显.其作用可能是通过促进牙周组织中BMP-2蛋白的表达,加速成骨细胞活动,促进骨形成,促进移动后的牙齿稳定.     

In vivo monitoring of the bone healing process around different titanium alloy implant surfaces placed into fresh extraction sockets

Objectives

Increasing surface roughness and coating with tricalcium phosphate of titanium and titanium alloy implants has been proposed to provide better rates of osseointegration. However, how these changes in surface topography and chemistry influence the osseointegration process of immediate implants placed in fresh extraction sockets is unclear. This study investigated the influence of three clinically employed implant surfaces on the early bone healing events in vivo.

Methods

Machined smooth implants were milled from grade 5 Ti6Al4V titanium. Surfaces were moderately roughened by grit blasting, which were then coated with tricalcium phosphate. Implants were placed into freshly extracted incisor sockets of mandibles of normal Wistar rats and left for 1, 3 and 9 weeks. Healing bone tissue around the implants was examined by histochemistry and immunocytochemistry to localise PCNA proliferative cells, and osteoblast differentiation markers osteopontin and osteocalcin. Positive synthesising cells were counted using image analysis.

Results

Histology indicated no differences in the amount or pattern of bone formation within the healing tissue surrounding the different implant surfaces. Bone healing occurred predominantly on exposed bone surfaces (distance osteogenesis) and not on the implant surface (contact osteogenesis). No differences were observed in the number or timing of PCNA, osteopontin and osteocalcin positive cells within the bone healing tissue around each of the implant analysed.

Conclusion

For immediately placed implants, the surface modifications investigated appeared to have little influence on the activity of bone forming cells surrounding the implant, probably due to the high level of distance osteogenesis seen within this scenario.

Clinical significance

For immediate placement of implants into fresh extraction sockets, titanium implants with roughened surfaces and coating with tricalcium phosphate have negligible influence in accelerating the early bone healing events of osseointegration.     

Comparison of two over-the-counter tooth whitening products using a novel system

Tooth whitening is one of the most widely accepted esthetic procedures in dentistry. Various treatment options include in-office and prescribed at-home bleaching procedures, over-the-counter bleaching kits, and whitening dentifrices. This study evaluated and compared a 6% hydrogen peroxide tooth bleaching gel delivered on polyethylene film (HP) with an 18% carbamide peroxide brush-applied liquid gel (CP). A total of 59 subjects completed this 2-week, examiner blind, randomized, parallel group study. Both treatments were applied twice daily for 2 weeks according to the manufacturer's instructions. Evaluations for oral safety and Vita tooth shade were conducted by a dental examiner at baseline and 2 weeks after product use. In addition, the ShadeVision System was used to determine changes in Vita shade and L*a*b* values. Based on both the examiner and ShadeVision System assessments, both treatments significantly improved tooth shade. Improvements in Vita tooth shade based on the adjusted mean for HP were 2.64 (P < 0.001) and 2.33 (P < 0.001) for the examiner and ShadeVision System assessments, respectively, compared with improvements of 1.04 (P = .004) and 0.42 (P = 0.029) for CP users, respectively. The difference between treatments was found to be significant for both the examiner (P = .005) and ShadeVision (P = .001) assessments. Findings from the L*a*b* data derived from the ShadeVision System were in agreement with Vita assessments, with significant differences for changes in L*, a*, and b* in favor of HP users (P = .001). In this study, the ShadeVision method of color analysis was relatively easy to use and demonstrated significant differences between 2 OTC whitening products using both Vitapan and L*a*b* means of assessment.     

载rhBMP2凝胶微球控释系统的设计与合成实验

目的:设计与合成rhBMP2新型控释载体,初步探讨其载药及降解性能。方法:用右旋糖酐 (dextran,dex)与甲基丙烯酸缩水甘油酯(glycidylmethacrylate,GMA)合成甲基丙烯酸缩水甘油酯右旋糖酐 (dex GMA),测定该凝胶微球溶胀系数Q,并对其载药、降解性能进行初步研究。结果:dex GMA在一定条件下可以成球,粒径与制备工艺密切相关;该凝胶微球溶胀参数 10. 9±5. 3;载药性能良好,在葡聚糖酶的作用下 20~40d内可以完全降解。结论:右旋糖酐基凝胶微球具有良好的溶胀性能,可生物降解,其粒径可控,作为生长因子载体,有望达到控释给药的目的,其制备工艺及理化性能有待进一步研究。     

Enhanced osteogenic differentiation of rat bone marrow mesenchymal stem cells on titanium substrates by inhibiting Notch3

ObjectiveThe role of the Notch pathway has already been identified as a crucial regulator of bone development. However, the Notch signaling pathway has gone largely unexplored during osseointegration. This study aims to investigate the role of Notch signaling on osteogenic differentiation of rat derived bone marrow mesenchymal stem cells (BMSCs) on sandblasted, large-grit, acid-etched (SLA) treated Ti disks.MethodsThe involved target genes in Notch pathways were identified by in vitro microarray and bioinformatics analyses with or without osteogenic induction. Adhesion, proliferation, and osteogenic related assay were subsequently conducted with target gene shRNA treatment.ResultsWe found that 11 genes in the Notch signaling pathway were differentially expressed after osteogenic induction on SLA-treated Ti disks, which included up-regulated genes (Notch2, Dll1, Dll3, Ncstn, Ncor2, and Hes5) and down-regulated genes (Notch3, Lfng, Mfng, Jag2 and Maml2). With Notch3 shRNA treatment, the adhesion and proliferation of BMSCs on SLA-treated Ti disks were inhibited. Moreover, the expression levels of alkaline phosphatase (ALP), osteocalcin (OCN), calcium deposition, BMP2 and Runx2 increased significantly compared with that observed in control groups, suggesting that the function of Notch3 was inhibitory in the osteogenic differentiation of BMSCs on SLA-treated titanium.ConclusionsInhibition Notch3 can enhance osteogenic differentiation of BMSCs on SLA-treated Ti disks, which potentially provides a gene target for improving osseointegration.     

Analysis of appositional bone formation using a novel rat experimental model

Aim:  To analyze the process of appositional bone formation using our original rat experimental model.
Materials and methods:  Rats were anesthetized and a ring made of polytetrafluorethylene was placed on the parietal bone surface in the surgical procedure. The time course of appositional bone formation was analyzed with histomorphometry and in situ hybridization for type I collagen and bone sialoprotein.
Results:  The rat experimental model allowed new bone to be formed on the pre-existing bone surface and persist for 12 weeks. We demonstrated that bone is apposed actively for the first 4 weeks and less actively thereafter.
Conclusions:  The experimental model may contribute to biological analysis for appositional bone formation expected to occur in clinical procedures such as alveolar bone augmentation and sinus lifting.     

Histological and immunohistochemical analyses of the chronology of healing process after immediate tooth replantation in incisor rat teeth

Abstract – Dental tissues have special characteristics, and its regenerative capacity is noteworthy. However, understanding the circumstances that lead to regeneration is challenging. In this study, the chronology of the healing process after immediate replantation of rat incisor teeth was examined by histological and immunohistochemical analyses within a 60‐day period. Thirty‐six male Wistar rats had their maxillary right incisors extracted and replanted after 15 min in saline storage. The rats were sacrificed immediately 3, 7, 15, 28, and 60 days after replantation. The histological analysis showed rupture of the periodontal ligament and formation of a blood clot, which started being replaced by a connective tissue after 3 days. At 7 days, the gingival mucosa epithelium was reinserted and areas of root resorption could be seen. At 15 days, the periodontal ligament was repaired. At 3 days, the pulp presented an absence of the odontoblast layer, which started being replaced by a connective tissue. This tissue suffered gradual calcification, filling the root canal at 28 and 60 days. The root ends were closed. The immunohistochemical analysis revealed greater expression of OP, OPG, and RANK proteins in the initial periods (0 and 3 days), while TRAP expression predominated at 28 and 60 days (P < 0.05). In conclusion, in delayed tooth replantation, there is great new bone formation activity in the earlier periods of the repair process, while a predominance of bone resorption and remodeling is observed in the more advanced periods.     

The effect of periosteal injury and masticatory micromovement on the healing of a mandibular distraction osteogenesis site

Objectives

Surgical periosteal injury and masticatory loading are likely factors affecting the healing of a mandibular DO site. This study is aimed to characterize the healing features of an early-phase mandibular DO site and assess the effects of these factors.

Design

Eighteen 3-6-month-old miniature pigs received a right mandibular osteotomy and were distracted for 5 days (1 mm/day) and consolidated for 0, 1 or 2 weeks (Groups A, B and C, respectively). Bone formation, chondrogenesis and vascular structure of the distraction site were measured using histological methods and their changes with consolidation time were characterized. The effect of periosteal injury was assessed by comparing the more severely injured lateral side with the less disturbed medial side. The effect of masticatory loading was evaluated by relating the healing features to the interfragmentary micromovement caused by soft-diet mastication.

Results

With consolidation time, bone formation and chondrogenesis became stronger whilst vascular structure became more mature. Compared to the medial side, bone formation and chondrogenesis on the lateral side were significantly delayed in Groups A and B, but not in Group C, in which periosteal recovery had occurred. No difference was found for vascular measurements between the medial and lateral sides. In Group B, bone formation, but not chondrogenesis or vascular structures, tended to be negatively correlated with the magnitude of masticatory micromovement during the distraction phase.

Conclusion

The results suggest that periosteal injury inhibits early mandibular DO site healing, whereas micromovement from soft-diet mastication mechanics has a negligible effect.     

Tomographic and histomorphometric evaluation of socket healing after tooth extraction using leukocyte- and platelet-rich fibrin: A randomized,single-blind,controlled clinical trial

The use of platelet concentrate in alveolar ridge preservation has been broadly studied. However, no randomized clinical trials with histomorphometric analysis and low risk of bias are available in the literature. We conducted a prospective, single-blind, parallel, randomized, controlled clinical trial to evaluate the efficacy of leukocyte- and platelet-rich fibrin (L-PRF) in socket preservation after tooth extraction. Additionally, the effect of L-PRF on bone formation was analyzed histologically using bone biopsy specimens obtained during implant placement.A total of 48 subjects who underwent a non-molar tooth extraction were randomly assigned to the L-PRF group (n = 24) or the control group (n = 24). Cone-beam computed tomographies were performed immediately after tooth extraction and at 3 months after tooth extraction, prior to implant surgery. A significant difference in bone resorption was registered 1 mm below the crest: 0.93 ± 0.9 mm for the L-PRF group and 2.27 ± 1.2 mm for the control group (p = 0.0001). Histomorphometric analysis showed a higher percentage of new bone formation in the L-PRF group compared with the control group. The values were 55.96 ± 11.97% and 39.69 ± 11.13%, respectively (p = 0.00001). These findings indicate that the administration of L-PRF should always be considered when socket preservation is planned (Clinicaltrials.gov NCT03408418).     

The synthesis of nano silver-graphene oxide system and its efficacy against endodontic biofilms using a novel tooth model

ObjectiveThe deleterious caustic effects of sodium hypochlorite (NaOCl) as a root canal irrigant makes it imperative that alternative methods are developed for root canal disinfection. The purpose of this study was to examine the antimicrobial efficacy of silver nanoparticles (AgNPs) synthesized on an aqueous graphene oxide (GO) matrix (Ag-GO), with different irrigant delivery methods to enhance the disinfection regimen, using a novel ex vivo infected tooth model.MethodsAgNPs were prepared by reducing AgNO₃ with 0.01 M NaBH₄ in presence of GO. Elemental analysis was performed with scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and scanning transmission electron microscopy (STEM) was used for size and morphology analysis of GO and Ag-GO. Nutrient stressed, multi-species biofilms were grown in prepared root canals of single-rooted teeth. The irrigants used were sterile saline, 1% and 2.5% NaOCl, 2% chlorhexidine gluconate (CHX), 17% EDTA and an aqueous suspension of 0.25% Ag-GO. The antimicrobial efficacy of the irrigants were performed with paper point sampling and measurement of microbial counts. The biofilm disruption in dentine tubule surfaces was analysed with confocal laser scanning microscopy (CLSM). The acquisition of total biovolume (μm³/μm²) and biofilm viability was performed using software BioImage_L. Two-way analysis of variance (ANOVA) with post hoc Tukey tests was used for data analysis with level of statistical significance set at P < 0.05.ResultsSEM/EDS analysis confirmed impregnation of Ag within the GO matrix. TEM images showed polygonal GO sheets and spherical AgNPs of diameter 20–50 nm, forming a network on the surface of GO sheets. The use of ultrasonic activation enhanced the efficacy of Ag-GO compared to 1% NaOCl, 2% CHX, 17% EDTA and sterile saline (P < 0.05). The microbial killing efficacy of 2.5% NaOCl was superior compared to the experimental groups. The maximum biofilm disruption, in dentine tubule surfaces, was achieved by 2.5% NaOCl, however Ag-GO caused a significant reduction of total biovolumes compared to the rest of the experimental groups (P < 0.05%).SignificanceThe successful documentation of the microbial killing and biofilm disruption capacity of Ag-GO is a promising step forward to explore its unique properties in clinical applications and biomaterials in dentistry.     

A retrospective classification of tooth injuries using a new scoring system

The WHO classification presently in use categorises dental trauma only according to the main injury. A new scoring system will now enable more precise and complete diagnosis of tooth injuries. In an initial retrospective investigation, 100 traumatised teeth were classified according to the WHO and the new scoring systems. Clinical and radiological examinations and another evaluations using the new scoring system were made at the time of follow-up examination. Avulsion, intrusion, and root fractures (score <30) showed the most unfavourable findings at the time of the accident. In comparison, the most favourable findings were shown by concussion and first degree crown fracture (score >70). A comparison to the WHO classification occasionally revealed noticeable score variations within a single WHO type of injury. Generally, a strong interdependence was observed between the evaluations at the time of the accident and at the time of the follow-up examination (P<0.001). If the score at the time of the accident was equal to or larger than 57, a successful therapy was usually ensured (P<0.001). The new scoring system enables more complete diagnosis as well as permitting statements to be made concerning prognosis. Received: 14 January 2000 / Accepted: 17 January 2000     

Evaluation of post-extraction healing after atraumatic axial tooth extraction using Benex system II versus conventional extraction: Randomized control trial

Background and PurposeTooth extraction is critical for dental treatment complications. One of the most discussed topics is socket healing after extraction. The Benex system allows extraction without causing unnecessary socket expansion by removing the tooth vertically, preserving both bone and soft tissue.AimTo assess postoperative healing signs, symptoms, and complications using the Benex extraction system and compare it with conventional extraction among patients at Umm Al-Qura University.MethodsThirty-eight patients with hopeless single-rooted teeth were included. They were divided into two equal groups: one in which teeth were extracted using the conventional method and one in which extractions were performed by Benex. The Benex system for tooth extraction was performed by drilling into the root canal, followed by screw insertion. Once the extractor was properly positioned, extraction was accomplished by turning the hand screw clockwise. At baseline, the wound size was evaluated. On days 1, 3, and 7 after extraction, telephone interviews were conducted to evaluate pain and post-extraction complications using a pain scale and questionnaire. Socket healing and wound size were evaluated after 2 and 4 weeks of extraction using the healing index and H₂O₂ epithelization test.ResultsThe Benex extraction system accelerated early soft-tissue healing and decreased pain and wound size compared with the control group. Conclusion. The Benex system is relatively safe and easy to use, but this does not eliminate the need for a degree of education and training. Proper selection of the case, knowledge of using the device, and implementation of that knowledge in the treatment planning are important factors in ensuring success with this system.     

新型硅磷酸钙用于大鼠拔牙位点保存的早期成骨性能研究

目的    通过SD大鼠拔牙窝模型研究硅磷酸钙（CPS）骨粉的体内成骨性能。方法    选择45只6周龄SD大鼠,全麻下拔除右侧上颌2颗磨牙后按照拔牙窝充填材料随机分为3组,每组15只。CPS组：拔牙后于拔牙窝内放入CPS骨粉,用Bio-Gide膜覆盖拔牙窝并缝合;Bio-Oss组：拔牙后于拔牙窝内放入Bio-Oss骨粉,用Bio-Gide膜覆盖拔牙窝并缝合;对照组：拔牙后不放置充填材料,直接用Bio-Gide膜覆盖拔牙窝并缝合。于术后2、4、8周分别处死每组大鼠5只并取材上颌骨,采用影像学和组织学检测方法测量并评价拔牙窝牙槽骨愈合情况。结果  所有大鼠样本在术后2、4、8周这3个时间点的拔牙位点骨体积分数、骨密度及骨小梁厚度均随着术后时间延长而增大。术后4周时,Bio-Oss组拔牙位点骨体积分数、骨小梁厚度大于CPS组和对照组（P < 0.05）。术后8周时,CPS组的拔牙位点骨体积分数、牙槽骨宽度、牙槽骨高度及骨密度略高于Bio-Oss组和对照组, CPS组的骨小梁厚度介于Bio-Oss组和对照组之间,但3组间各指标的差异均无统计学意义（均P > 0.05）。组织学观察发现,术后8周CPS组和Bio-Oss组仅可见少量的未降解材料,周围有较多新骨形成,骨质较致密。结论    CPS在体内具有良好的促成骨能力和降解性能,可有效减少拔牙后牙槽骨萎缩,具有作为位点保存充填材料的潜力。     

A clinical study to evaluate the efficacy of a novel tray based tooth whitening system

OBJECTIVES: The study was designed to test the whitening efficacy of a new prefabricated tray based whitening system. METHODS: A parallel, examiner blind, stratified two group clinical study was carried out in the Department of Fixed and Removable Prosthodontics, Leeds Dental Institute, United Kingdom. Forty-nine male and female subjects aged 18-70 years participated in the study and they underwent both clinical and digital evaluation at baseline, 3, 7 and 14 days, respectively. The non-intervention control group was given no treatment and the test group received a tray based whitening system (Colgate Visible White PF Mint, Colgate Palmolive Company, NY, USA) that uses a 6% hydrogen peroxide gel applied in the tray twice daily for 30 min. Digital images of teeth were captured using a Jai 3CCD digital camera under an annular LED illumination array (SCHOTT North America, Inc., USA) and the data obtained was used to calculate colour parameters (L(*), a(*) and b(*)) and whiteness index WIO. RESULTS: Clinical data and digital data showed significant difference for the Visible White group from the control group for the mean difference in its values from the baseline to each visit (p<0.001). Digital data showed significant correlation to clinical data. CONCLUSION: In the present study statistically significant tooth whitening was evident after 3 days treatment with the tray based whitening system and colour improved with continued usage over 14 days. It also supports our previous study results that the WIO index is appropriate for assessing changes in tooth whiteness.