Tooth roughness after subgingival root planing

Surface roughness of enamel and root surface after scaling, root planning and polishing procedures: An in-vitro study

Objectives

The aim of this study was to evaluate enamel and root surface roughness on exracted human teeth by using different tecniques (ultrasonic scaler, hand instruments, polishing paste, pumice and air powder system).

Materials and methods

A total of 200 samples were divided into two groups (enamel and root) randomly with 100 samples for each enamel and root groups. The groups were divided into 5 subgroups: Group I: ultrasonic scaler, group II: hand instruments, group III: polishing paste, group IV: pumice, group V: air-powder. Surface roughness (Ra) was assessed with Mitutoyo SJ-410 device. The one-way analysis of variance (ANOVA) test along with the Tukey test was used for statistical analysis. P values less than 0.05 were considered statistically significant.

Results

The use of ultrasonic scalers caused the highest roughness increase on the enamel surface (0.935 ​± ​0.010), whereas the use of pumice was the least (0.896 ​± ​0.018) (p ​< ​0.05). There was a significant difference between ultrasonic scalers and all the groups (hand instruments, polishing paste, pumice and air powder system) on enamel surface (p ​< ​0.05). Maximum surface roughness increase was observed in the ultrasonic scalers on root surface. There was a significant difference between ultrasonic scalers and polishing paste, pumice and air powder on root surface, respectively (p ​< ​0.05).

Conclusion

The use of ultrasonic scalers cause more rough enamel and root surfaces than hand instrumentation and polishing tecniques.

Clinical relevance

Uneven surfaces adversely affect the intended periodontal healing by creating a retention area of microbial dental plaque.

Qualitative and quantitative differences in the subgingival microbiome of the restored and unrestored teeth

BACKGROUND AND OBJECTIVE

Metal-based dental restorations with a subgingival outline may enhance plaque accumulation and bacterial colonization. This study aimed to investigate whether metal-based restorations influence the composition of subgingival microbiome.

MATERIAL AND METHODS

Per subject one site with a metal-based restoration and one contra-lateral site without a restoration were selected on basis of radiographic bone loss ≤2 mm, restoration outline at sulcus level/subgingivally, pocket depth ≤4 mm, and no root canal treatments. Subgingival samples were collected with sterile paper-points, and microbial profiles were obtained by 16S rRNA gene amplicon sequencing. Restorations were sampled with an Arkansas-stone and the metal composition was determined using energy-dispersive X-ray spectroscopy.

RESULTS

A total of 22 sites from 11 subjects were included. No significant differences for the clinical parameters were found between the restored and unrestored sites. The average age of the restorations was 14.9 ± 7.1 years. Firmicutes was the most prevalent phylum at the restored sites (32% vs 20% of the reads of the unrestored sites, P = 0.016), and Actinobacteria at the unrestored sites (33% vs 18% of the reads of the restored sites, P = 0.01). Overall, sequences clustered into 573 operational taxonomic units (OTUs). Species richness of the restored sites was significantly higher than species richness of the unrestored sites (117 ± 32 and 96 ± 20 OTUs, respectively, P = 0.013). No associations between the metal composition and bacterial profiles were found.

CONCLUSION

This study shows that metal-based restorations may enhance colonization of Firmicutes and the neighboring pocket may harbor more diverse microbial communities.

Evaluation of three different manual techniques of sharpening curettes through a scanning electron microscope: a randomized controlled experimental study

OBJECTIVE

The purpose of this study was to compare the effectiveness of three different techniques for manually sharpening of periodontal curettes (PCs) by examining the blades with the aid of scanning electron microscope (SEM).

METHODS

Three groups were considered based on three sharpening methods used: group A (moving a PC over a stationary stone); group B (moving a stone over a stationary PC) and group C (moving a PC over a stone fixed, placed on a 'sharpening horse'). After the sharpening, the blades were examined using SEM. The SEM images were assessed independently by five different independent observers. An evaluation board was used to assign a value to each image. A preliminary pilot study was conducted to establish the number of samples. Pearson's correlation test was used to assess the correlations between measurements. anova test with Bonferroni's post hoc test was used to compare the three groups.

RESULTS

Sixty PCs (20 PCs per group) were used in this study. Statistically significant differences emerged between the three groups (P-value = 0.001). Bonferroni's test showed that the difference between groups A and B was not statistically significant (P-value = 0.80), while it was significant for the comparisons between groups A and C (P-value = 0.005) and between groups B and C (P-value = 0.001).

CONCLUSIONS

The sharpening technique used in group C, which involved the use of the sharpening horse, proved the most effective.

Loss of tooth substance during root planing with various periodontal instruments: an in vitro study

Ultrasonic and power-driven instrumentation is gaining in significance as an acceptable alternative to manual periodontal root treatment. Some question whether they do not remove too much tooth substance. Various ultrasonic scalers, hand instruments and two power-driven systems were compared by assessing the loss of tooth substance due to root instrumentation. Quantitative analysis of this effect of the instruments used was performed on 20 freshly extracted, non-periodontally involved, large human molars. In the first study, 40 specimens were randomly assigned to four groups of treatment: combined use of ultrasonic scaler and Periopolisher diamond-coated inserts (US-POL), hand instruments (MANUAL), Perioplaner-Periopolisher system (PPL-POL) and Periokit ultrasonic-designed scalers (PERIOKIT). The second study involved two treatment groups, ultrasonic scaler alone and hand instruments, each allocated with 20 teeth (small root fragments). An unpaired two-tailed t test was carried out for both studies to compare the average weight loss of root substance with the modes of instrumentation. The level of significance was set at p<or=0.05. The overall results of the first and second experimental trials did not reveal obvious differences in weight loss between the manual, ultrasonic or power-driven root treatments. Based on the results of these two comparative studies, the power-driven inserts or the various ultrasonic scalers tested did not remove more tooth substance than conventional hand instruments. They may thus be a useful alternative for the debridement of root surfaces.

Scanning electron microscope evaluation of two methods of resharpening periodontal curets: a comparative study

BACKGROUND

Effective root planing demands sharp cutting edges on dental curets. However, after several strokes, they become dull and must be resharpened frequently. The purpose of this study was to evaluate by scanning electron microscopy (SEM) the quality of the cutting edge of periodontal curets resharpened by 2 different methods.

METHODS

Forty new detachable Gracey curets were used in this study. After similar blunting, all instruments were resharpened either with 10 strokes using an Arkansas fine-grit sharpening stone (AR), or with 7 strokes using a high-grit and -density aluminum oxide stone (CH). The cutting edges of each instrument were examined using SEM at 1 mm and 2 mm from the tip before and after the resharpening procedure. Bevel measurement and the amount of functional and non-functional wire edges (WE) on the cutting edge were evaluated. Data were statistically analyzed using analysis of variance (ANOVA) with repeated measures, 2-way ANOVA, and Fisher's exact test.

RESULTS

After blunting and resharpening, differences in bevel between groups were statistically non-significant. Generally, after resharpening, there were significantly more functional and non-functional WE in the AR group than in the CH group. There were significantly more instruments with a complete absence of WE in the CH group.

CONCLUSIONS

The CH stone resulted in a smoother and better cutting edge than the AR stone. The procedure was easy to perform and required fewer strokes of the curet on the stone.

Merits of soft nitriding scalers

BACKGROUND

It has been demonstrated that nitriding modifies the physical characteristics of metals. The purpose of this study was to evaluate the changes induced by 3 levels of inexpensive soft nitriding treatments on commercial sickle scalers.

METHODS

Taglite scalers (NT) were soft nitrided for 30 (SN30), 60 (SN60), or 90 (SN90) minutes. The cumulated scaled material was weighed every 10 strokes x 10 and thereafter every 1,000 to 8,000 strokes by an automatic scaling apparatus against epoxy resin. Weight differences were used to indicate abrasion resistance; the relative efficiency (RE) was calculated as the ratio of scaled amount at a given number of strokes (SN/NT). The hardness and the tensile strengths were determined for each soft nitriding treatment level. The nitrided layer thickness of representative SN scalers was observed by electron probe x-ray microanalysis.

RESULTS

The SN60 was not significantly different from SN30 or SN90, but the SN90 was more efficient than SN30 for the first 100 strokes (P<0.01). The RE of all SN scalers was significantly greater (2.3 to 2.7 times) than the NT scalers from the beginning of the study and throughout all time periods (SN90 > SN60 > SN30); it increased further during the first 100 strokes (9.7 to 15.5 times), indicating the NT scalers wore out faster than SN scalers. The untreated scalers' performance decreased to 10% of baseline after 100 strokes; but even after 1,000 strokes, the SN60 and SN90 performed better than new untreated scalers. Thereafter, all scalers' performance, including SN scalers, decreased. While the NT blades ceased to cut measurable amounts after 7,000 to 8,000 strokes, all SN scalers continued to cut. Although SN90 scalers had the thickest soft layer and were the hardest (P<0.01), the SN60 had the highest tensile strength (P <0.01), suggesting that it might be the safest in practice.

CONCLUSIONS

Sixty minutes of soft nitriding treatment of commercially available taglite scalers seem to be the optimal treatment duration to increase their durability, on the order of 100 to 1,000 times, without jeopardizing safety for clinical use.

Effects of repeated hand instrumentation on the marginal portion of a cast gold crown

A study was conducted to evaluate the effects of repeated hand instrumentation on the marginal portion of a cast gold crown. Seven extracted periodontally diseased premolars were used. The finishing line of the preparation was placed on the root surface and then the crown was cast and cemented in the usual manner. One proximal surface of each sample was divided into 2 areas: root planing (RP) area and RP plus polishing (RPP) area. The marginal portion of the crown was measured to give a baseline value using a surface roughness- and profile-analyzing system. Then, the marginal portion was painted with a waterproof pen. RP was performed to remove paint in the RP area with the curets. In the RPP area, RP followed by polishing was done by silicone polishing points and a rubber cup with polishing paste. The relevant procedures and measurements were repeated 3 times in each area. Changes in the sample roughness and profile were evaluated and compared between the 2 techniques. The results showed that repeated instrumentation altered the surface of the marginal portion of the cast gold crown, resulting in increased roughness in both areas (P < 0.01). However, the roughness of the RPP area was considerably restored to the baseline value by polishing after RP. Therefore, it is suggested that polishing after RP smoothes the marginal portion of the cast gold crowns and appears to be an efficient prophylactic system.

Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature

OBJECTIVES

The roughness of intraoral hard surfaces can influence bacterial plague retention. The present review evaluates the initial surface roughness of several intraoral hard materials, as well as changes in this surface roughness as a consequence of different treatment modalities.

METHODS

Articles found through Medline searches were included in this review if they met the following criteria: 1) stated threshold surface roughness values and reputed change in surface roughness due to different manipulation techniques; or 2) included standardized surface conditions that could be compared to the treated surface.

RESULTS

Recently, some in vivo studies suggested a threshold surface roughness for bacterial retention (Ra = 0.2 micron) below which no further reduction in bacterial accumulation could be expected. An increase in surface roughness above this threshold roughness, however, resulted in a simultaneous increase in plaque accumulation, thereby increasing the risk for both caries and periodontal inflammation. The initial surface roughness of different dental materials (e.g., teeth, abutments, gold, amalgam, acrylic resin, resin composite, glass ionomer or compomer and ceramics) and the effect of different treatment modalities (e.g., polishing, scaling, brushing, condensing, glazing or finishing) on this initial surface roughness were analyzed and compared to the threshold surface roughness of 0.2 micron. The microbiological effects of these treatment modalities, if reported, are also discussed and compared to recent in vivo data.

SIGNIFICANCE

Based on this review, the range in surface roughness of different intraoral hard surfaces was found to be wide, and the impact of dental treatments on the surface roughness is material-dependent. Some clinical techniques result in a very smooth surface (compressing of composites against matrices), whereas others made the surface rather rough (application of hand instruments on gold). These findings indicated that every dental material needs its own treatment modality in order to obtain and maintain a surface as smooth as possible.

Clinical evaluation of the speed and effectiveness of subgingival calculus removal on single-rooted teeth with diamond-coated ultrasonic tips

Several studies have found incomplete calculus removal during periodontal treatment with traditional hand curets, sonic, and ultrasonic instruments. This study evaluated the speed and effectiveness of subgingival calculus removal with new diamond-coated ultrasonic tips on single-rooted teeth. Single session subgingival scaling and root planing was performed on 80 teeth with 5 to 12 mm probing depths in 15 patients. Each patient provided groups of 4 teeth that were randomly treated with either hand curets (HAND); standard smooth ultrasonic tip (US); or fine grit (FINDIAM) or medium grit (MEDDIAM) diamond-coated ultrasonic tips. The time taken to reach the therapeutic endpoint of a clean, smooth root surface in a defined region on each tooth with each instrument by the 3 therapists with differing experience levels was recorded. The teeth were then atraumatically extracted, stored in a surfactant, photographed at 10X, and the percent of calculus present in the area of the pocket or on a comparable control surface calculated by histometric point counting. ANOVA and paired t tests showed that mean percent remaining calculus on treated versus control surfaces was HAND 4.6 +/- 5.3 versus 57.5 +/- 28.2, US 4.7 +/- 6.4 versus 54.4 +/- 25.9, FINDIAM 4.3 +/- 5.2 versus 37.5 +/- 22.1, and MEDDIAM 3.4 +/- 4.2 versus 50.7 +/- 20.1, respectively (all P < 0.01). The mean time in seconds to reach the clinical endpoint ranged from HAND 289 +/- 193, US 194 +/- 67, FINDIAM 167 +/- 71, to MEDDIAM 147 +/- 92. All powered instruments were significantly faster than HAND (P < 0.05), but did not differ from each other. On a 0 = "smooth" to 3 = "rough" scale, most often HAND resulted in "smooth" surfaces (10/20), the powered tips of all types "slight" surface roughness (10/20 each), and US the most "moderate" roughness (7/20). There were no differences in percent calculus remaining, surface roughness, or time spent among the 3 treating clinicians despite their varying experience levels. The results of this study showed that percent calculus remaining was <5% with all the instruments given time ad libitum on a given root surface. Root roughness was generally slightly greater with all 3 powered tips. All of the powered instruments took significantly less time than the HAND. Both DIAM tips took less time than US. Diamond-coated ultrasonic tips appeared to be much more efficient than HAND or US in removing calculus in moderate-deep probing depths on single-rooted teeth in vivo.

A newly-developed electrodeposited diamond scaler with high abrasive resistance

A diamond scaler on which blade diamond particles were coated by electrodeposition was developed to improve the abrasive resistance of scaler blades. The electrodeposited coating was tested with diamond particles of four different sizes, designated D-4000 with 2 to 4 microns diameter of the particles; D-800 with 12 to 25 microns; D-600 with 20 to 30 microns; and D-400 with 30 to 40 microns. The abrasive resistance of the scalers was examined quantitatively using a recently-developed automatic scaling apparatus that simulated the scaling process of hand instrumentation, as well as SEM observation of the blades. A series of abrasion tests suggested that all the diamond scalers except D-4000 showed better abrasive resistance than the control (D-0), and that D-600 showed the highest abrasive resistance and cutting quality. The SEM observation also suggested that D-600 and D-400 might have higher abrasive resistance. Furthermore, the profilometric evaluation of the surface roughness of the scaled natural dentin after hand instrumentation indicated that the average surface roughness increased in the order of D-4000, D-800, D-600, and D-400, although no marked differences were observed among D-4000, D-800, D-600 and D-0, but not D-400. These results suggested that the electrodeposited diamond scaler with 20 to 30 microns diamond particles (D-600) might have marked abrasive resistance as well as cutting quality without remarkable damage to the tooth surface after conventional scaling procedure.

Quantitative evaluation of the cutting quality and abrasive resistance of scalers

An automatic scaling apparatus that simulated the scaling process of hand instrumentation was developed to quantitatively analyze the cutting quality and abrasive resistance of scalers. We first tested 4 synthetic resins as the abraded material. Of the 4 synthetic resins tested, polycarbonate resin proved most similar to dentin. The effects of lateral scaling forces (700, 500, and 300 dyne) and scaler angles (70 degrees to 95 degrees) on the cutting quality and abrasive resistance of scalers were evaluated quantitatively by the amount of the abraded material worn away in 1,000 strokes. Comparison of the 3 scaling forces showed a greater amount of abrasion at higher force than that at lower force. This suggests that the decrease in the amount due to abrasion could be compensated by increasing the lateral scaling force. Regarding the scaler angle, results indicated that the amount of material removed increased with an increase of the scaler angle up to 70 degrees, but then rapidly decreased at an angle of 90 degrees or more. The most effective scaling angle was 87 degrees, and this was not affected by scaling force. These results suggest that a greater amount of removal could be obtained at a scaling angle of 87 degrees and a scaling force of 700 dyne. The present findings suggested the automatic scaling apparatus could be a useful tool for quantitatively evaluating the cutting quality and abrasive resistance of scalers.

The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man. A review of the literature

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.

A scanning electron micrographical study of root surfaces and subgingival bacteria after hand and ultrasonic instrumentation

The effects of hand and ultrasonic instrumentation on root surface topography and subgingival plaque were studied. One approximal subgingival root surface on each of two single rooted teeth of six patients was root planed. The opposing proximal surfaces were not treated and served as controls. On each patient, the two test surfaces were randomly treated by hand or ultrasonic instrumentation (Cavitron) until clinically smooth. The teeth were extracted, divided into mesial and distal sides, and processed for scanning electron microscopy (SEM). The observations were restricted to an area 2 mm by 3 mm just coronal to the plaque-free zone. The root surfaces were scanned by SEM, both at low (x 100) and at higher magnifications (x 5000). At low power, a photomontage was produced of the surface area of the test teeth. At low magnifications (x 100, x 500), the topography resulting from hand instrumentation appeared smooth with parallel scratches compared to scaly but flat surfaces with occasional deep gouges with the ultrasonic method. At high magnifications (x 5000), tooth surfaces were similar in topography when instrumented by either hand or ultrasonic methods. Root surfaces were covered in some areas by a fibrillar-like membrane that resembled fibrin. Individual bacteria were found on the surfaces of this material. On other areas not covered by this membrane, bacterial plaque was only observed when tooth surfaces had not been contacted by either hand or ultrasonic instrumentation.

Scanning electron microscope evaluation of wear of stainless steel and high carbon steel curettes

Root planing depends on quality instrument cutting edges. The sharpness and wear of stainless steel (SS) and high carbon steel (HCS) dental curettes were compared before and after standardized root planing procedures. Forty working edges of dental curettes, 20 of each alloy, were examined by scanning electron microscope (SEM) prior to any root planing (control), after 15 strokes, and after 45 strokes. Root planing was carried out on freshly extracted, single-rooted teeth, mounted in natural positions in mannikin jaws. Working areas measuring 3 x 5 mm were marked on root surfaces previously exposed by periodontitis. Each working edge was examined at points 1 mm and 2 mm from the tip under the same magnification (x 240). Microscopic observations showed that edge deformation increased from the control (factory sharpened) group, to the "15 stroke" group, and from the "15" to the "45 stroke" group, in both SS and HCS curettes. SS curettes, however, demonstrated significantly more wear than HCS curettes. After 45 strokes, only 5% of the SS curettes were sharp, compared to 20% of the HCS curettes. While 65% of the SS curettes showed severe edge deformation by the end of the study, only 20% of the HCS curettes were severely deformed (P less than 0.01). The results indicate that HCS curettes are more resistant to wear than SS curettes. Further study is indicated to evaluate the relationship between actual bevel dimensions and root planing effectiveness.

Scanning electron microscope evaluation of wear of dental curettes during standardized root planing

Root planing relies upon the quality of instrument cutting edges. This study evaluated the sharpness and wear of some dental curettes available in the market following standardized root planing procedures. Nine working edges of nine Gracey No. 1/2 DE curettes, three each from three different manufacturers, were used as controls. These unused factory-sharpened edges were examined by scanning electron microscope (SEM). Eighteen edges of nine curettes of the same brands were likewise examined after root planing procedures. Root planing was carried out on extracted one-rooted teeth mounted in natural positions in manikin jaws. Working areas measuring 3 X 5 mm were marked on root surfaces previously exposed by periodontitis. Root planing procedures included 15 vertical strokes done by either Side 1 or Side 2 of each instrument in relation to a single working area of a tooth, and the same procedure repeated 3 times using the opposite side of the curette. All working edges were examined at points 1 and 2 mm from the tip under 500 times magnification. Edge deformation increased significantly from the control group to the "15-stroke" group and from the "15-stroke" group to the "45-stroke" group. Factory-sharpened curettes (control) were sharp, with functional wire edges present on 55% of the specimens. After 15 strokes, nonfunctional wire edges and narrow edge deformations with bevels measuring less than 15 mu were present. After 45 strokes eight cutting edges (88.9%) showed bevels wider than 15 mu. The difference between the three brands was not significant in any group (i.e., controls, 15 strokes, 45 strokes). Further study is indicated to evaluate the relationships between bevel dimensions and root planing effectiveness.

Surface roughness and marginal behaviour of experimental and commercial composites: an in vitro study

Three experimental inhomogeneous microfilled composites (IMC) containing spherical prepolymerized particles with an interpenetrating network (IPN) were compared with the reference materials Estic MF, Adaptic and the amalgam Dispersalloy in vitro. With surface roughness tests, different polishing procedures were investigated. In addition an SEM analysis of the margins of Class I fillings using a replica technique was performed. With the same technique the proximal boxes of Class II fillings were analysed to further determine the best method to handle the materials clinically. The experimental materials showed a superior adaptation to the walls of proximal boxes of Class II cavities than the reference materials. This superiority was increased by the use of a filled bonding agent. The influence of viscosity, filler load and glass transition point on adaptation and polymerization shrinkage are discussed. It was concluded that especially designed diamonds with very fine abrasive particle size (40 micrograms and 15 micrograms) are the best for finishing and contouring composite fillings. Based on the results of this study it is recommended to use the experimental material for clinical investigations.

Histological assessment of periodontally involved cementum

Contamination of periodontally involved cementum by bacterial substances such as lipopolysaccharide (LPS) is considered a major reason for root planing. The purpose of the present study was to investigate the presence and location of lipid and polysaccharide within involved cementum as compared with uninvolved cementum. Frozen sections were prepared from the decalcified roots of 36 periodontally diseased and two control teeth. Serial sections were stained for either lipid (Oil-Red-O) or polysaccharide (Alcian Blue - PAS) and also with haematoxylin & eosin (H & E) or Huberstone's gram stain. Specimens of involved and uninvolved cementum were then examined under the light microscope for assessment of differences. Involved cementum from 12 of the periodontally diseased teeth exhibited strongly PAS-positive stained processes penetrating 3-7 mum into the surface of cementum from overlying plaque. Such processes were not observed in uninvolved cementum, suggesting a possible bacterial origin. Lipid granules were noted in only one involved specimen where they were situated up to 10 mum beneath the cemental surface. Similar granules were observed within plaque deposits but never in uninvolved cementum, again suggesting a possible bacterial origin. H & E and gram-stained specimens revealed the presence of microbial deposits in surface defects and within defects at the cemento-dentinal junction (CDJ), as well as penetration of micro-organisms into cementum in the absence of any surface defects. The results indicate that although lipid and polysaccharide of possible bacterial origin may be present within the 10 mum surface zone of involved cementum, the finding of microbial deposits down to the level of the CDJ suggests that all periodontally involved cementum should be removed during root planing, in order to achieve a root surface free of bacterial contamination.

The surface roughness of restorative materials and dental tissues after polishing with prophylaxis and polishing pastes

The effect of prophylaxis and polishing pastes on bovine tooth hard tissues and dental materials was investigated in vitro. Four restorative dental materials (gold, amalgam, a conventional composite, a microfilled composite), brought to a standard surface finish, and two bovine dental hard tissues (enamel, dentin) were polished with ten different prophylaxis and polishing pastes. Before polishing, SEM photographs were taken of all materials, and surface profiles were obtained of every sample. After polishing, surface profiles from every sample and SEM photographs of every material/paste combination were obtained. Using the same techniques, two-step polishing procedures were also investigated. The evaluation of the surface profiles and the rated SEM photographs (by 20 dentists) showed significant paste and material differences. There was a significant correlation (0.82) between the results of the surface profiles and the SEM ratings. Almost all pastes roughened the surfaces of dental restorative materials and only a few pastes showed a tendency to render the surfaces of dental restorative materials and only a few paste showed a tendency to render the surfaces of dental hard tissues smoother. Therefore, if polishing is indicated after periodontal treatment, the paste used should be selected carefully. Since the surface roughness of conventional composites increases tremendously during each polishing with pastes, their surfaces should be avoided when using polishing pastes. If polishing with a paste in indicated, conventional composites should be polished afterwards with aluminium silicate coated discs.

Furcation morphology relative to periodontal treatment. Furcation entrance architecture

The furcation entrance diameter of first permanent molar teeth has been investigated in a sample of 114 maxillary and 103 mandibular teeth, and found to be smaller than the blade face width of commonly used periodontal curettes in 58% of the furcations examined. It is suggested that because of this size disparity curettes when used alone may not be suitable for root preparation in this area as part of periodontal therapy. Alternative methods of instrumentation require clinical appraisal before recommendation. The buccal furcation entrance diameters of the maxillary first molar teeth examined tended to be smaller than either the mesiopalatal or distopalatal. Similarly the buccal entrance diameter in the mandibular first molar teeth examined tended to be smaller than the linqual. The mesiodistal widths at the cementoenamel junction of both maxillary and mandibular first molar teeth were found to have very low correlation with their furcation entrance diameters. Large teeth therefore do not necessarily have large furcation entrance diameters.

Calculus removal and loss of tooth substance in response to different periodontal instruments. A scanning electron microscope study

The efficiency of calculus removal and the amount of lost tooth substance resulting from the use of hand curette, ultrasonic curette and rotating diamond and Roto-Pro points were examined by scanning electron microscopy (SEM). Root surfaces of mandibular incisors placed in a jaw model were cleaned of adhering deposits, photographed by SEM and evaluated at a standard magnification by three examiners. Scores were given for remaining calculus (RCI) and loss of tooth substance (LTSI) according to defined index criteria. The results revealed that calculus removal was most complete following diamond instrumentation, whereas the ultrasonic curette was least efficient in this respect. Hand curette, ultrasonic curette and Roto-Pro removed about the same amount of tooth substance whereas the diamond removed considerably more than the others. The diamond regularly removed all the cementum and left deep instrumental marks in the dentin; it seems advisable to avoid the use of such instruments in periodontal depuration.

Root surface roughness in response to periodontal instrumentation studied by combined use of microroughness measurements and scanning electron microscopy

Root surface roughness, resulting from calculus removal by hand curette, ultrasonic curette and rotating diamond or Roto-Pro points, was examined by combined use of microroughness measurements and scanning electron microscopy (SEM). Mandibular incisors were placed in a jaw model with a rubber "gingiva" in an attempt to simulate a clinical situation. After cleaning with the various instruments, the surface roughness was measured by an industrial profilometer followed by SEM evaluation. A microroughness index (MRI) was developed and showed that the instruments could be separated into three groups, where the hand curette produced least roughness, followed by the Roto-Pro instrument, while the ultrasonic curette and the diamond left the most uneven surfaces. A SEM roughness index (SRI) based on defined criteria, corresponded well with the results from the profilometer measurements, except that using this index the diamond scored higher than the ultrasonic curette. This was probably due to considerable calculus remnants remaining in the ultrasonic specimens. Characteristic features of the root surface morphology of the cleaned teeth are described. It is concluded that the combined use of microroughness measurements and SEM is of considerable value in this type of studies since more information may be obtained than by any of these methods used separately.

New method of viewing root surfaces

A new technique, density slicing and color coding, was utilized in examining root surfaces. This technique proved to be an adjunct in evaluating tooth surfaces and appeared to have future dental application. Density slicing and color coding vividly portrays the root surface, the depth of depressions and the concentration and flow pattern of calculus, enhancing the ability of the naked eye to visualize root surface topography.

The effects of two ultrasonic instruments on root surfaces

The Orbison ultrasonic instrument and the Cavitron ultrasonic dental unit were compared for the smoothness of the root surfaces they produced. Twenty teeth were analyzed with the scanning electron microscope and classified as to rough or smooth. Both instruments produced similar degrees of smoothness on the root surfaces with minimal scarring. Application of these instruments to the root surface apical to the epithelial attachment produced residual smearing of some of the collagenous fibrils.