Analysis of early biofilm formation on oral implants in man

Biofilm formation on oral implants can cause inflammation of peri-implant tissues, which endangers the long-term success of osseointegrated implants. It has been reported previously that implants revealing signs of peri-implantitis contain subgingival microbiota similar to those of natural teeth with periodontitis. The purpose of the first part of this study was an atraumatic, quantitative investigation of biofilm formation on oral implant abutments; the objective of the second part was to investigate whether Haemophilus actinomycetemcomitans and Porphyromonas gingivalis were present in the crevicular fluid around oral implants. Biofilm formation on 14 healing abutments, inserted for 14 days in 10 patients, was analysed quantitatively by use of secondary-electron and Rutherford-backscattering-detection methods. A 16S rRNA-based polymerase chain reaction detection method was used to detect the presence of H. actinomycetemcomitans and P. gingivalis in the crevicular fluid. For this investigation, samples of sulcus fluid were collected with sterile paper points at four measurement points per abutment. The difference between biofilm coverage of supragingival surfaces (17.5 +/- 18.3%) and subgingival surfaces (0.8 +/- 1.0%) was statistically significant (P < 0.05). By use of universal primers, bacteria were found in all the samples taken, although the two periodontal pathogens were not found in any of the samples. The absence of periodontal pathogens from the sulcus fluid during initial bacterial colonization, despite massive supragingival biofilm formation, substantiates the assumption that cellular adherence of peri-implant tissue by means of hemidesmosoma, actin filaments and microvilli reduces the risk of formation of anaerobic subgingival pockets.     

Comparative analysis of biofilm formation on dental implant abutments with respect to supra- and subgingival areas: polytetrafluoroethylene versus titanium

The aim of the present in vivo study was to examine the effect of polytetrafluoroethylene (PTFE) surfaces on biofilm formation on dental implant abutments in comparison to titanium surfaces. Fifteen modified abutments with incorporated PTFE plates were inserted in 10 patients for 14 days. Scanning electron microscopy techniques were used to examine biofilm formation on different surfaces and to determine the percentage of surface coverage. Significantly less biofilm was detected on PTFE surfaces than on titanium surfaces. The results of this study reveal that PTFE surfaces reduce biofilm formation to a minimum on dental implant abutments. Int J Prosthodont 2011;24:373-375.     

The influence of abutment surface roughness on plaque accumulation and peri‐implant mucositis

Bacterial adhesion to intra-oral, hard surfaces is firmly influenced by the surface roughness of these structures. Previous studies showed a remarkable higher subgingival bacterial load on rough surfaces when compared to smooth sites. More recently, the additional effect of a further smoothening of intra-oral hard surfaces on clinical and microbiological parameters was examined in a short-term experiment. The results indicated that a reduction in surface roughness below R_a=0.2 μm, the so-called “threshold R_a”, had no further effect on the quantitative/qualitative microbiological adhesion or colonisation, neither supra- nor subgingivally. This study aims to examine the long-term effects of smoothening immoral hard transgingival surfaces. In 6 patients expecting an overdenture in the lower jaw, supported by endosseus titanium implants, 2 different abutments (transmucosal part of the implant): a standard machined titanium (R_a=0.2 μm) and one highly polished and made of a ceramic material (R_a=0.06 μm) were randomly installed. After 3 months of intra-oral exposure, supra- and subgingival plaque samples from both abutments were compared with each other by means of differential phase-contrast microscopy (DPCM). Clinical periodontal parameters (probing depth, gingival recession, bleeding upon probing and Periotest-value) were recorded around each abutment. After 12 months. the supra- and subgingival samples were additionally cultured in aerobic, CO,-enriched and anaerobic conditions. The same clinical parameters as at the 3-month interval were recorded after 12 months. At 3 months, spirochetes and motile organisms were only detected subgingivally around the titanium abutments. After 12 months, however, both abutment-types harboured equal proportions of spirochetes and motile organisms, both supra- and sub-gingivally. The microbial culturing (month 12) failed to detect large interabutment differences. The differences in number of colony forming units (aerobic and anaerobic) were within one division of a logarithmic scale. The aerobic culture data showed a higher proportion of Gram-negative organisms in the subgingival flora of the rougher abutments. From the group of potentially “pathogenic” bacteria, only Prevotellu inter-media and Fusobacterium nucleatum were detected after anaerobic culturing and again the inter-abutment differences were negligible. Clinically, the smoothest abutment showed a slightly higher increase in probing depth between months 3 and 12, and more bleeding on probing. The present results confirm the findings of our previous short-term study, indicating that a further reduction of the surface roughness, below a certain “threshold R_a”(0.2 μm), has no major impact on the supra- and subgingival microbial composition.     

Atomic force microscopic study of commercially available implant abutments

Background: Clinical studies have reported a correlation between the surface roughness of implant abutments and the rate of supragingival and subgingival plaque formation. In order to maintain periimplant health, it is important to understand the relationship between abutment surface characteristics and plaque formation. Purpose: The aim of this study was to use high image resolution imaging techniques for analysis of implant abutment surface topography. Materials and Methods: Five commercially available implant abutments (Brånemark, Nobel Biocide, AB, Goteborg, Sweden, Astra, Astra Tech AB, Mondal, Sweden, IMZ, Friatec AG, Mannheim, Germany, Steri-Oss, Denar Corp, Anaheim, Calif, USA, and POI, Kyocera Corp, Kyoto, Japan) were visually and quantitatively characterized using an atomic force microscope. Results: Statistical analysis by analysis of variance and Fishers's Protected Least Significant Differences showed significant differences (p<.05) between arithmetic mean deviation values of surface relative to the center plane (Sa). Power spectral density analysis also was effective as a spacing parameter. Sectional profiles measured the exact length, depth, or height of the specific features on the images. Conclusions: Within the limits of this study, the Brånemark, Astra and IMZ abutments displayed turning marks in x direction from the procedure. The Steri-Oss abutment showed smoothest surface among the five abutments tested.     

The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man

Abstract In the oral cavity, an open growth system, bacterial adhesion to the non-shedding surfaces is for most bacteria the only way to survive. This adhesion occurs in 4 phases: the transport of the bacterium to the surface, the initial adhesion with a reversible and irreversible stage, the attachment by specific interactions, and finally the colonization in order to form a biofilm. Different hard surfaces are available in the oral cavity (teeth, filling materials, dental implants, or prostheses), all with different surface characteristics. In a healthy situation, a dynamic equilibrium exists on these surfaces between the forces of retention and those of removal. However, an increased bacterial accumulation often results in a shift toward disease. 2 mechanisms favour the retention of dental plaque: adhesion and stagnation. The aim of this review is to examine the influence of the surface roughness and the surface free energy in the adhesion process. Both in vitro and in vivo studies underline the importance of both variables in supragingival plaque formation. Rough surfaces will promote plaque formation and maturation, and high-energy surfaces are known to collect more plaque, to bind the plaque more strongly and to select specific bacteria. Although both variables interact with each other, the influence of surface roughness overrules that of the surface free energy. For the subgingival environment, with more facilities for microorganisms to survive, the importance of surface characteristics dramatically decreases. However, the influence of surface roughness and surface-free energy on supragingival plaque justifies the demand for smooth surfaces with a low surface-free energy in order to minimise plaque formation, thereby reducing the occurrence of caries and periodontitis.     

Fluorescence spectroscopy of dental calculus

BACKGROUND: Correct diagnosis of the presence and extent of subgingival calculus is important for periodontal treatment planning and reassessment after periodontal therapy. Traditional tactile methods often lack sensitivity. The present investigation shall contribute to understanding the fundamental fluorescence properties that may be useful for optical detection of both supra- and subgingival calculus. OBJECTIVES: The aim of this study was to investigate emission spectra from supra- and subgingival calculus under a wide range of excitation wavelengths. METHODS AND RESULTS: Extracted human molars with either supragingival or subgingival calculus deposits on the root surface were selected (n = 3 each). Emission spectra were recorded from the calculus of each tooth and corresponding areas of clean root surfaces using a fluorescence spectrophotometer at excitation wavelengths from 360 nm up to 580 nm in steps of 20 nm. The spectra were corrected for the wavelength dependent instrument sensitivity and normalized to peak intensity (the highest peak was set at 1.0). Emission spectra of calculus exhibited distinct fluorescence bands between 570 and 730 nm not present in clean root surfaces. This fluorescence emission was strongest for excitation wavelengths from 400 to 420 nm. No differences were observed between supra- and subgingival calculus. CONCLUSIONS: Human dental calculus can clearly be differentiated from clean root surfaces by emission spectrophotometry. The characteristic fluorescence emission of supra- and subgingival calculus may be due to a variety of porphyrin derivatives and may provide the basis for future diagnostic procedures.     

Reuse of healing abutments: an in vitro model of plasma cleaning and common sterilization techniques

The reuse of transgingival healing abutments has been advocated by several implant manufacturers, but cleaning and sterilization procedures to yield clean and optimal surfaces have yet to be developed. The objective of this in vitro project was to investigate various cleaning and sterilization regimens for the removal of biological debris to support reattachment of subgingival connective tissue. Simulated clinical healing abutment surfaces were exposed to culture medium with serum for 1 hour to simulate biological exposure. Simulated healing abutment surfaces not contaminated by serum were used to represent the "as-is" healing abutment surface without prior in vivo use. The discs were cleaned with detergent before sterilization by ultraviolet light (UV) or steam autoclaving (AC) both with and without 1- and 5-minute plasma cleaning (PC). A series of surface analytical techniques (XPS, AES, and surface contact angles) and in vitro analysis of cell attachment and spreading using gingival fibroblasts were performed. After exposure to the simulated biological conditions, clinical cleaning followed by UV resulted in contaminated surfaces and relatively high levels of cell attachment. PC before UV treatment enhanced surface energetics but did not affect cell attachment and spreading. AC increased surface wetting angles; which were decreased somewhat by previous PC. Cell attachment was significantly reduced by AC. Although some increase in cell attachment after longer plasma cleaning was noted in the AC group, no difference in cell spreading was seen in any AC group. Cell spreading seemed to be less for all AC groups compared with all UV, as-is, and control groups. Although certain cleaning (PC) and sterilization (UV) procedures can be effective for cleaning transgingival healing abutments, those using AC are questionable due to their propensity for organic and inorganic contamination and unfavorable surface alteration.     

The effect of titanium implant abutment surface irregularities on plaque accumulation in vivo.

The purpose of this study was 2-fold to: 1) evaluate in vitro the surface texture of titanium implant abutments after exposure to plastic scalers, an air-powder abrasive system, rubber cup polishing with flour of pumice, and untreated control abutments; and 2) compare plaque accumulation in humans on abutments treated with the above methods. In part I, 5.5 mm abutments were instrumented for 30 seconds per 90 degrees segment with the respective methods. The surface character was compared to untreated controls using SEM at 260X magnification. The control abutments revealed prominent milling marks and small pits; plastic scalers slightly smoothed the milling marks and created microscratches; the air-powder abrasive largely obliterated the milling marks and caused some surface pitting; the rubber cup with flour of pumice removed the milling marks and created a smooth swirl pattern. None of the instrumentation appeared to roughen the surface. In the clinical experiment (part II), four abutments, one of each type, were placed in 12 patients for a period of 7 days, during which the patients performed no oral hygiene. At the end of 7 days, the abutments were retrieved and processed for SEM. A digitizer and software program were used to determine the percent of total abutment surface area covered by plaque. The demarcation of supragingival and subgingival plaque was well delineated. The total mean percent surface area of plaque ranged from 52.06% for the air-powder abrasive to 55.29% for the plastic scalers.(ABSTRACT TRUNCATED AT 250 WORDS)     

The comparative effect of ultrasonic scalers on titanium surfaces: an in vitro study

BACKGROUND: Professional maintenance is as important for patients with dental implants as it is for patients with natural teeth. However, no proper maintenance instruments have been available for implant patients. The purpose of this in vitro study was to compare the effects of a new ultrasonic scaler (VR), a conventional ultrasonic scaler (SP), and a plastic scaler (PS) on titanium surfaces. METHODS: To simulate subgingival conditions, the implant healing abutments were connected to acrylic resin blocks with artificial gingiva using silicon impression material. The abutments were painted with ink as an artificial form of debris. The ink was removed with the VR, SP, or PS scaler for 60 seconds under standardized conditions, and the removal rate was calculated. The roughness of the abutment surface was measured with a profilometer and observed by scanning electron microscopy (SEM). RESULTS: The removal rate using the VR and SP scalers was higher than that using the PS scaler. No significant differences in the surface roughness or SEM observations were found among the VR, SP, or PS scalers. CONCLUSIONS: In this preliminary study, the new ultrasonic scaler and conventional ultrasonic scaler were shown to be useful for removing artificial debris and produced no significant damage to titanium surfaces compared to plastic scalers. We concluded that new and conventional ultrasonic scalers with a non-metal tip would be suitable for implant maintenance.     

Master cast accuracy in single-tooth implant replacement cases: an in vitro comparison. A technical note

PURPOSE: This in vitro study evaluated the accuracy of master casts obtained by using (1) copings modified by sandblasting and coating their roughened surfaces with impression adhesive before final impression procedures and (2) gold machined UCLA abutments as impression copings in final impression procedures for single-tooth implant replacement cases. MATERIALS AND METHODS: A polymeric resin model with a standard single implant was used to simulate a clinical situation. A group of 20 impressions were made using square impression copings sandblasted to roughen their external surfaces at a supragingival level and then coated with Impregum polyether adhesive; a second group of 20 impressions were made using gold machined UCLA abutments as impression copings. The castable part of the UCLA abutments was secured with resin to the gold machined section of the UCLA abutment to prevent movement of the castable part itself on the gold machined portion during the impression procedures; the castable portion of the UCLA was also coated with the Impregum polyether adhesive to improve the stability of the gold machined UCLA abutment inside the impression material. Master casts fabricated for both groups were analyzed to detect rotational position change of the hexagon on the implant replicas in the master casts with reference to the resin model. RESULTS: The rotational position changes of the hexagon on implant replicas were significantly less variable in the master casts obtained using gold machined UCLA abutments as impression copings than in the master casts achieved with the roughened square impression copings. DISCUSSION: Improved precision of the impression was achieved when the gold machined UCLA abutments were used as impression copings. CONCLUSION: This report suggests that using gold machined UCLA abutments as impression copings in the final impression procedures can enable the clinician to achieve a more accurate orientation of the implant replicas in the laboratory master casts for single-tooth implant replacement cases.     

The condition of the soft tissues at tooth and fixture abutments supporting fixed bridges A microbiological and histological study.

In 10 partially edentulous patients provided with fixed bridgework supported by the combination of tooth and titanium fixture abutments, the condition of the soft tissues surrounding the abutments was examined. Sampling of supra- and subgingival plaque was performed from both teeth and fixtures. The samples were analyzed regarding the total bacterial counts, the relative distribution of bacterial morphotypes and the cultivable microflora. From each patient, soft tissue biopsies were obtained from 1 tooth and 1 fixture abutment, and the specimens were analyzed for the presence and extension of inflammatory cell infiltrates. The microbiological examination showed that the distribution of bacterial morphotypes in the supra- and subgingival plaque both at teeth and fixtures were similar, irrespective of localization and type of abutment. Nonmotile rods dominated the microflora, whereas spirochetes were either not detected or occurred in very low proportions. From the histological analysis, it was found that a majority of the soft tissue biopsies (75-80%) from both tooth and fixture sites contained only very small inflammatory cell infiltrates.     

A Novel Universal Cementation Technique for Implant‐Supported Crowns with Subgingival Margins

Restoration of implant crowns with subgingival margins has always been a challenge. If done precisely it leads to better treatment outcomes and prognosis. An incorrect technique and improper execution of the luting procedure are known to cause a high incidence of peri‐implant disease due to incomplete elimination of the luting agent. Deep subgingival abutment margins are difficult to recognize, and cement removal in these cases becomes complicated if the sulcus depth is greater than 3 mm. Irrespective of the type of instrument used to remove the excess cement, scratches on the abutment and some cement remnants are consistently noticed. Therefore elimination of excess luting agent before the prosthesis is inserted intraorally is considered an effective technique to prevent complications due to excess luting agent. This article presents a chairside universal technique for cementation of implant crowns on abutments with deep subgingival margins. This technique attempts to minimize the amount of excess cement in peri‐implant tissue.     

Chemical and morphological studies of the acquired pellicle formed subgingivally on dentin in vivo

The morphological appearance and chemical composition of the subgingival pellicle were studied, using Auger analysis and scanning and transmission electron microscopy. A pellicle was formed on pieces of dentin (2 X 2 X 1 mm), prepared from freshly extracted teeth after root planing. The dentin slabs were inserted for 2 h into healthy gingival sulci. Control slabs cemented supragingivally were used for comparison. The results confirmed the presence of an organic film on the surface of all slabs. Auger analysis of the organic film showed the presence of Ca in the supragingival integument but not in the subgingival integument. The subgingival pellicle was in all cases thicker than the supragingival pellicle. The transmission and scanning electron microscopy observations confirmed the presence of a film essentially free of bacteria on the subgingival specimens and also indicated a possible morphological difference between the supra- and sub-gingival pellicle.     

Fluoride distribution in human dental calculus obtained from different sites on the tooth surface

We examined the site specificity of fluoride (F) distribution in human dental calculus. Teeth with supra- and subgingival calculus were obtained from patients who resided in non-fluoridated areas in Japan and China. Sequential layers of the dental calculus (30 μm thick) were abraded by an abrasive micro-sampling technique and fluoride and phosphorus in the powdered samples were analyzed. Fluoride concentrations were highest in the outer, lowest in the middle and intermediate in the inner layers of dental calculus in general. In the outermost layers fluoride concentrations were highest in calculus found near the tooth cervix both in supra- and subgingival calculus. Fluoride concentrations decreased markedly toward the apical region in subgingival calculus. while it did not change toward the incisal or occlusal region in supragingival calculus. In the inner layers, fluoride concentrations in both supra- and subgingival calculus were not affected by position on the teeth. Fluoride concentrations in subgingival calculus near the apex were lower than in supragingival calculus near the incisal or occlusal region. It was concluded that the fluoride concentrations differ in different regions of dental calculus, probably due to their different mechanisms of formation.     

Soft tissue integration versus early biofilm formation on different dental implant materials

Objective

Dental implants anchor in bone through a tight fit and osseo-integratable properties of the implant surfaces, while a protective soft tissue seal around the implants neck is needed to prevent bacterial destruction of the bone-implant interface. This tissue seal needs to form in the unsterile, oral environment. We aim to identify surface properties of dental implant materials (titanium, titanium-zirconium alloy and zirconium-oxides) that determine the outcome of this “race-for-the-surface” between human-gingival-fibroblasts and different supra-gingival bacterial strains.

Methods

Biofilms of three streptococcal species or a Staphylococcus aureus strain were grown in mono-cultures on the different implant materials in a parallel-plate-flow-chamber and their biovolume evaluated using confocal-scanning-laser-microscopy. Similarly, adhesion, spreading and growth of human-gingival-fibroblasts were evaluated. Co-culture experiments with bacteria and human-gingival-fibroblasts were carried out to evaluate tissue interaction with bacterially contaminated implant surfaces. Implant surfaces were characterized by their hydrophobicity, roughness and elemental composition.

Results

Biofilm formation occurred on all implant materials, and neither roughness nor hydrophobicity had a decisive influence on biofilm formation. Zirconium-oxide attracted most biofilm. All implant materials were covered by human-gingival-fibroblasts for 80–90% of their surface areas. Human-gingival-fibroblasts lost the race-for-the-surface against all bacterial strains on nearly all implant materials, except on the smoothest titanium variants.

Significance

Smooth titanium implant surfaces provide the best opportunities for a soft tissue seal to form on bacterially contaminated implant surfaces. This conclusion could only be reached in co-culture studies and coincides with the results from the few clinical studies carried out to this end.     

龋齿、牙周炎患牙和健康牙的菌斑生物膜特征

目的研究牙面菌斑生物膜特征与口腔疾病的关系。方法选择牙周健康而牙冠严重龋坏的龋齿5颗、无龋损而极度松动的牙周炎患牙6颗及正畸原因拔除的健康牙4颗,在扫描电镜下,观察分析龈上、龈下及移行生态区的菌斑生物膜特征。结果龋齿、牙周炎患牙和健康牙的牙面均观察到细菌混合物组成的菌斑生物膜,健康牙菌斑生物膜以球菌为主,放线菌和短杆菌少量;龋齿牙的龋坏处为坏死组织和细菌,龋边缘及龈沟处的球菌和短杆菌较健康牙多;牙周炎患者牙菌斑生物膜的细菌种类多,在龈上、龈下移行处可见典型的玉米棒状菌斑或以杆菌为主的紧密附着菌斑,龈下可见球菌、杆菌、梭菌及螺旋体等构成的复杂菌斑。结论龋齿、牙周炎患牙和健康牙菌斑生物膜细菌组成、集聚秩序和立体结构不同,菌斑生物膜的形成与细菌的附着、集聚、生长有关,也与局部病变密切相关。     

Fatigue resistance and failure mode of novel-design anterior single-tooth implant restorations: influence of material selection for type III veneers bonded to zirconia abutments

Objectives: This study assessed the fatigue resistance and failure mode of type III porcelain and composite resin veneers bonded to custom zirconia implant abutments. Material and methods: Twenty‐four standardized zirconia implant abutments were fabricated. Using the CEREC 3 machine, type III veneers of standardized shape were milled in ceramic Vita Mark II or in composite resin Paradigm MZ100. The intaglio surfaces of the restorations were hydrofluoric acid etched and silanated (Mark II) or airborne‐particle abraded and silanated (MZ100). The fitting surface of the abutments was airborne‐particle abraded, cleaned, and inserted into a bone level implant (BLI RC SLActive 10 mm). All veneers (n=24) were adhesively luted with a zirconia primer (Z‐Prime Plus), adhesive resin (Optibond FL) and a pre‐heated light‐curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was simulated, starting with a load of 40 N, followed by stages of 80, 120, 160, 200, 240, and 280 N (20,000 cycles each). Samples were loaded until fracture or to a maximum of 140,000 cycles. Groups were compared using the life table survival analysis (Logrank test at P=.05). Results: Mark II and MZ100 specimens fractured at an average load of 216 N and 229 N (survival rate of 17% and 8%), respectively, with no difference in survival probability (P=.18). Among the fractured samples, 40% of the failures were at the abutment level for Mark II and 27% were at the abutment level for MZ100. No exclusive adhesive failures were observed. Conclusions: Type III Mark II and Paradigm MZ100 veneers showed similar fatigue resistance when bonded to custom non‐retentive zirconia implant abutments. The bond was strong enough to induce abutment fractures. MZ100 presented a higher percentage of “friendly” failures, i.e. maintaining the restoration–abutment adhesive interface and the abutment itself intact. To cite this article:
Magne P, Paranhos MPG, Burnett LH Jr, Magne M, Belser UC. Fatigue resistance and failure mode of novel‐design anterior single‐tooth implant restorations: influence of material selection for type III veneers bonded to zirconia abutments.
Clin. Oral Impl. Res. 22 , 2011; 195–200.
doi: 10.1111/j.1600‐0501.2010.02012.x     

The natural history and clinical course of calculus formation in man

This paper describes levels and progression of supra- and subgingival calculus undisturbed by active professional intervention or home care between 1970 and 1985 in Sri Lanka, or when removed at regular intervals between 1969 and 1988 in Norway. In the Sri Lankan tea laborers, both supra- and subgingival calculus formation started before age 14 years. At 40 years of age, all participants and almost all teeth and tooth surfaces had calculus. Tea laborers who both smoked tobacco and chewed betel had significantly higher calculus scores than those who only had one of these habits, and those who neither chewed nor smoked had the lowest calculus scores. Teeth with calculus showed a significantly higher rate of loss of attachment than teeth that remained calculus free. For the Norwegians who had enjoyed regular dental care throughout their lives, supragingival calculus did not increase in frequency from adolescence to the forties. Approximately 70% of the interproximal surfaces were calculus free after 40-50 years of age. Subgingival calculus scores, although low, showed some increase with longer times of exposure. On average, each person had 0.4 interproximal surfaces with subgingival calculus as they approached 50 years of age. In this Norwegian population, subgingival calculus had no impact on loss of attachment.     

Effects of bur abrasive particle size and abutment composition on preparation of ceramic implant abutments

STATEMENT OF PROBLEM: Amid increasing use of preparable ceramic implant abutments, there is a lack of quantitative data to show which abrasive particle size of diamond bur yields the fastest reduction and provides the smoothest surface. PURPOSE: The research aim was to determine the effects of diamond bur abrasive particle size and abutment material composition on preparation efficiency, prepared surface roughness, and surface deterioration of diamond burs. MATERIAL AND METHODS: Fifteen alumina (Cera Base) and 15 zirconia (ZiReal) implant abutments were each machined using a high-speed hand piece with a diamond bur having 1 of 3 abrasive particle sizes (150, 100, or 30 microm) (n=5). Control abutments (n=5) were analyzed without machining. Abutments were weighed before starting and between machining cycles. Three profilometry measurements (root mean square surface roughness) were made for each abutment. Scanning electron micrographs were made of each bur. Lost abrasive particles were then counted on each micrograph through a randomly placed template. Two-way analysis of variance (alpha=0.05) was used to test for significant effects. RESULTS: Bur abrasive particle size and ceramic type had a significant interactive effect on the amount of material removed (P<.001). Super coarse (150 microm) burs yielded the roughest surfaces for each abutment material (P<.001), and prepared alumina surfaces were rougher than zirconia surfaces (P<.001). Super coarse burs showed the highest proportion of lost particles (P<.001). Abutment composition did not significantly affect bur wear. CONCLUSION: Super coarse burs yielded the most efficient material removal for alumina abutments. All abrasive particle sizes removed a similar amount of material from zirconia abutments. Fine-grained alumina abutments experienced greater material removal and rougher prepared surfaces compared with zirconia abutments. Material was removed by an intergranular fracture mechanism for alumina abutments, in contrast to transgranular fracture for zirconia abutments.