Surface coatings on dental cementum incident to periodontal disease. (II). Scanning electron microscopic confirmation of a mineralized cuticle

Scanning electron microscopy study to analyze the morphological characteristics of root surfaces after application of Carisolv gel in association with scaling and root planing: In vitro study

Context:

There has been considerable interest in the use of chemical-assisted root detoxification. Chemical agents have been proposed to facilitate calculus removal.

Aims:

A study was carried out to analyze the morphological characteristics of the root surfaces after application of Carisolv gel in association with scaling and root planing under scanning electron microscopy (SEM).

Settings and Design:

The Department of Periodontics of the K. M. Shah Dental College and Hospital, Vadodara, (Gujarat, India).

Materials and Methods:

Sixty periodontally compromised extracted human teeth were randomly assigned to four groups: (1) scaling and root planning (SRP) alone; (2) passive topical application of Carisolv + SRP; (3) active topical application of Carisolv + SRP; (4) multiple applications of Carisolv + SRP. Carisolv gel was applied to the root surfaces for 30 seconds, followed by scaling and root planing, consisting of 30 strokes, with Gracey curettes in an apical-coronal direction, parallel to the long axis of the tooth. The only exception was group 4, where the roots were instrumented until a smooth, hard, and glass-like surface was achieved. All specimens were further analyzed by SEM.

Statistical Analysis:

The Analysis of Variance (ANOVA) method was used.

Results:

Active application of Carisolv gel produced more extensive morphological changes than passive application and SRP alone. When multiple applications of Carisolv with SRP were performed, there was a significant decrease in the smear layer compared to a single application of the gel, either passively or actively.

Conclusions:

The Carisolv gel failed to remove the smear layer completely, especially with a single application, independently of the method of application. This study documented that the Carisolv gel produced changes in the root morphology of periodontally compromised teeth, only when it was applied actively and multiple times.

Scanning electron microscopic analysis of the effect of CarisolvTM gel on periodontally compromised human root surfaces

The aim of this study was to analyze, under scanning electron microscopy (SEM), the morphologic characteristics of root surfaces after application of CarisolvTM gel in association with scaling and root planing (SRP). Sixty periodontally compromised extracted human teeth were randomly assigned to 6 groups: 1) SRP alone; 2) passive topical application of CarisolvTM + SRP; 3) active topical application of CarisolvTM + SRP; 4) multiple applications of CarisolvTM + SRP; 5) SRP + 24% EDTA; 6) topical application of CarisolvTM + SRP + 24% EDTA. CarisolvTM gel was applied to root surfaces for 30 s, followed by scaling and root planing, consisting of 50 strokes with Gracey curettes in an apical-coronal direction, parallel to the long axis of the tooth. The only exception was group 4, in which the roots were instrumented until a smooth, hard and glass-like surface was achieved. All specimens were further analyzed by SEM. The results showed that the treatment with CarisolvTM caused significant changes in root surface morphology of periodontally compromised teeth only when the chemical agent was actively applied (burnishing technique). CarisolvTM failed to remove the smear layer completely, especially with a single application, independently of the method of application. Multiple applications of CarisolvTM were necessary to achieve a smear layer reduction comparable to that obtained with 24% EDTA conditioning.

Localization of Porphyromonas gingivalis-carrying fimbriae in situ in human periodontal pockets

Fimbriae, which are involved in adherence, constitute an important pathogenic factor of Porphyromonas gingivalis. In vivo, however, the distribution of P. gingivalis-carrying fimbriae is unknown. The localization of P. gingivalis-carrying fimbriae was examined in situ. From 19 patients with severe periodontitis and P. gingivalis, we obtained 20 teeth with periodontal tissue attached, with and without immunolocalized fimbriae. Eleven teeth were subjected to light microscopy, 9 to electron microscopy. In 6 of the 11 samples examined, we detected positive reactions with an anti-P. gingivalis-fimbriae serum, located in the cementum-attached plaque area in the deep pocket zones. In the so-called 'plaque-free zones', P. gingivalis-carrying fimbriae were immunocytochemically observed to reside in contact with the dental cuticle in 6 of the 9 samples examined. These findings suggest that P. gingivalis-carrying fimbriae are strongly related to adherence to the root surface at the bottoms of human periodontal pockets.

Surface wear on cervical restorations and adjacent enamel and root cementum caused by simulated long-term maintenance therapy

BACKGROUND

In an in vitro study, the surface wear on cervical restorations and adjacent enamel and root cementum caused by different tooth-cleaning methods in simulated long-term therapy was investigated.

METHODS

Cervical restorations of amalgam (Oralloy), modified composite resin (Dyract), glass-ionomer cement (ChemFill Superior), and composite (Tetric) were instrumented by POL (polishing), CUR+POL (curette and polishing), US+POL (ultrasonic device with polishing) and the polishing agents Cleanic and Proxyt in a computer-controlled test bench. Treatment time corresponding to a real-time period of 5 or 10 years. Substance loss from instrumented surfaces was measured with a digital gauge. A three-way anova was used in the statistical evaluation.

RESULTS

The results showed that POL led to slight substance loss, which was greater using Cleanic (27 microm) than Proxyt (5 microm). CUR+POL produced a significantly greater substance loss than did US+POL, with 186 microm versus 35 microm on glass-ionomer cement, respectively, and 123 microm versus 18 microm, respectively, on root cementum, followed by composite (111 microm versus 27 microm, respectively), polyacid modified composite resin/compomer (89 microm versus 36 microm), amalgam (75 microm versus 19 microm), and enamel (32 microm versus 23 microm).

CONCLUSIONS

As opposed to the use of US+POL or POL, substance loss on cervical restorations and especially root cementum must be expected to result from tooth-cleaning during long-term maintenance treatment using CUR+POL.

Invasion of dentinal tubules by oral bacteria

Bacterial invasion of dentinal tubules commonly occurs when dentin is exposed following a breach in the integrity of the overlying enamel or cementum. Bacterial products diffuse through the dentinal tubule toward the pulp and evoke inflammatory changes in the pulpo-dentin complex. These may eliminate the bacterial insult and block the route of infection. Unchecked, invasion results in pulpitis and pulp necrosis, infection of the root canal system, and periapical disease. While several hundred bacterial species are known to inhabit the oral cavity, a relatively small and select group of bacteria is involved in the invasion of dentinal tubules and subsequent infection of the root canal space. Gram-positive organisms dominate the tubule microflora in both carious and non-carious dentin. The relatively high numbers of obligate anaerobes present-such as Eubacterium spp., Propionibacterium spp., Bifidobacterium spp., Peptostreptococcus micros, and Veillonella spp.-suggest that the environment favors growth of these bacteria. Gram-negative obligate anaerobic rods, e.g., Porphyromonas spp., are less frequently recovered. Streptococci are among the most commonly identified bacteria that invade dentin. Recent evidence suggests that streptococci may recognize components present within dentinal tubules, such as collagen type I, which stimulate bacterial adhesion and intra-tubular growth. Specific interactions of other oral bacteria with invading streptococci may then facilitate the invasion of dentin by select bacterial groupings. An understanding the mechanisms involved in dentinal tubule invasion by bacteria should allow for the development of new control strategies, such as inhibitory compounds incorporated into oral health care products or dental materials, which would assist in the practice of endodontics.

Subgingival polishing with a teflon-coated sonic scaler insert in comparison to conventional instruments as assessed on extracted teeth (II). Subgingival roughness

AIM

To assess the root surface roughness and topography on extracted teeth using different instruments.

MATERIAL AND METHODS

In the present study, laser profilometry was used to examine the 3-D roughness values Ra and Rz and topography of root surfaces of periodontally-involved teeth instrumented in vivo with curette, conventional ultrasonic device, conventional or teflon-coated sonic scaler insert, or the Periotor instrument (12 teeth per instrument type), and compare these with uninstrumented cementum surfaces.

RESULTS

The roughness values Ra and Rz of the roots treated with the different instruments showed a similar pattern: curettes and the Periotor instrument produced the smoothest surfaces (Ra about 1.5 microm, Rz 30 microm); the 4 other instruments created similar Ra values of approximately 2-3 microm and Rz roughness of about 50-70 microm, which equals the untreated root surface. For Ra, the difference between the curette or the Periotor instrument and the teflon-coated sonic insert or ultrasonic insert was significant, and for Rz, a significant difference was found between the curette or the Periotor instrument and ultrasonic insert. As opposed to surfaces debrided with the Periotor and teflon-coated sonic scaler, it appears that hand instruments markedly reconfigure surfaces.

CONCLUSION

The lowest root-surface roughness values were obtained with hand instruments. The teflon tubing on the sonic scaler insert effected no change of topography or roughness as compared to uninstrumented, control surfaces. However, it must be pointed out that hard-tissue removal was not investigated.

Rationale of mechanical plaque control

Patients who have received extensive periodontal treatment also demonstrate a high susceptibility to periodontal disease. Maintenance of periodontal health following therapy includes a lifelong supportive care consisting of daily removal of the microbial plaque by the patient, supplemented by professional care in an individually designed programme. Mechanical supragingival plaque control by self care is of utmost importance. The goal is to create a positive attitude by information and motivation to give the patient knowledge and confidence. The patient should be advised to use appropriate aids and technique. A soft brush, an interspace brush, interdental tooth brushes or tooth picks are recommended in periodontal patients. Professional tooth cleaning involves removal of supragingival plaque from all tooth surfaces using mechanically driven instruments and fluoride prophy paste and, when indicated, removal of calculus and subgingival plaque. Disclosing solution is used to visualize the plaque to the patient and to the clinician in order to reinforce instruction in oral hygiene. Oral hygiene measures alone seem to have limited effect on subgingival microflora in cases of severe disease. In shallow and moderately deep pockets a good plaque control can change the subgingival flora towards a more "healthy" composition. Subgingival plaque removal is performed with hand- and/or ultrasonic instruments. Cracks within the cementum, grooves, fissures, resorption lacunae, furcations may create difficulties in cleaning the root surface. Ultrasonic instrumentation has a beneficial effect in creating a smooth surface without extensive removal of cementum. Besides, the cavitational activity contributes to plaque removal which makes the instrument further suitable during maintenance therapy. The result of the debridement is assessed on the healing response in the tissues. The frequency of maintenance visits must be given on an individual basis according to the needs of every special patient. The visit includes plaque evaluation (disclosion), oral hygiene instruction, probing depth measurements, registration of bleeding on probing, scaling (plaque removal) if indicated, tooth polishing, fluoride application and radiographs if indicated. The goal is to identify and treat signs of recurrence of periodontal disease in order to prevent further loss of attachment.

Effects of tetracycline-containing gel and a mixture of tetracycline and citric acid-containing gel on non-surgical periodontal therapy

The purpose of this study was to assess the clinical and microbiological effects of a newly developed root conditioning gel system containing tetracycline or a mixture of tetracycline and citric acid on non-surgical periodontal therapy. Sixty-four (64) single-rooted teeth with a probing depth of 4 to 6 mm were randomly subjected to one of the following four treatments; 1) root planing alone (RP group); 2) tetracycline-containing gel alone (TCG group); 3) root planing plus tetracycline-containing gel (RP + TCG group); or 4) root planing plus a mixture of tetracycline and citric acid-containing gel (RP + TC-CAG group). Probing depth, attachment level, and tooth mobility were measured and the presence of dental plaque and gingival inflammation was recorded at baseline and after 2, 4, 8, and 12 weeks. Subgingival plaque samples from each site were collected at the same visits and examined with phase contrast microscopy for proportions of motile rods and spirochetes. Plaque index, gingival sulcus bleeding index (SBI), probing depth, and attachment level decreased significantly in all groups compared to the baseline values (P < 0.05). A significant decrease in probing pocket depth was noted after 12 weeks in RP + TC-CAG group compared to the other groups (P < 0.05). Significantly more gain in attachment was detected in the RP + TC-CAG group compared to the TCG group (P < 0.05). Tooth mobility scores also decreased later in the study. A significant decrease in the proportion of motile rods was found primarily in the RP + TC-CAG group.(ABSTRACT TRUNCATED AT 250 WORDS)

The periodontally-involved root surface

Recent years have seen much research on the periodontally-involved root surface. Many of these studies have produced results which suggest that plaque contaminants of the root surface are only superficially placed, and capable of being removed by gentle means. Further research has attested to the difficulties in rendering periodontally-involved root surfaces free of calculus deposits by instrumentation, yet clinical studies show that periodontal disease can be managed by root planing. It is concluded that root surface debridement is best assessed on the basis of the healing response and that it should aim to disrupt plaque on and remove plaque from the periodontally-involved root surface rather than to remove part of the root surface itself.

Effectiveness of open flap root debridement with rubber cups, interdental plastic tips and prophy paste. An SEM study

This study was designed to ascertain whether conservative cleaning of surgically-exposed root surfaces can achieve complete plaque removal. 10 single-rooted teeth (40 surfaces) from 4 patients with advanced periodontitis were included in the study. After flap reflection, the root surfaces were cleaned using only rubber cups, EVA plastic tips and prophy paste. No attempt was made to remove calculus. Immediately after treatment, the teeth were extracted. Then root surfaces were systematically examined in the scanning electron microscope to detect any residual bacteria (plaque). 27 of the 40 treated root surfaces were plaque-free. On the other 13 root surfaces, only a few isolated small islands of plaque were detected. On the other hand, relatively extensive areas of the root surfaces exhibited calculus. Bacterial plaque accumulation was routinely observed on the rough calculus surfaces and at the periphery of the hard deposits. These results demonstrate that the instruments used in this study can successfully remove plaque from exposed root surfaces. However, subgingival calculus that is firmly attached to root surfaces virtually always harbors plaque bacteria; such deposits require more aggressive instrumentation (scalers, curettes) for removal.

Root substance removal by scaling and root planing

The amount of root substance removed by scaling and root planing is largely unknown. The present study evaluated in vitro the root substance loss caused by a defined number of working strokes at known forces. Forty extracted teeth with loss of connective tissue attachment into the middle third of the roots were washed and embedded in plaster, leaving one entire corono-apical tooth aspect exposed. The teeth were reproducibly repositioned in a bench-vise, where a profilometer repeatedly measured root surface levels at the same location. In a standard area of the roots a total of 40 working strokes were applied. Low forces were used in 30 teeth and high forces in 10 teeth. The forces were recorded using a piezo-electric receiver built into the upper shank of the curet. Root substance loss was measured after 5, 10, 20, and 40 working strokes. The results showed that the mean low force used per working stroke across all 40 strokes was 3.04 Newtons for the low forces, and 8.48 Newtons for the high forces. Mean cumulative loss of root substance across 40 strokes was 148.7 microns at low forces, and 343.3 microns at high forces. The mean force per stroke increased slightly across the 40 strokes, while substance removal per stroke decreased. Substance removal per stroke during strokes 1 to 5 was 6.8 microns using low forces and 20.6 microns using high forces. During strokes 21 to 40 mean removal per stroke was 2.3 microns at low forces, and 5.6 microns at high forces. These results suggest that high forces remove more root substance, and loss per stroke becomes less with increasing numbers of strokes.

An in vitro investigation on the loss of root substance in scaling with various instruments

There are differing opinions as to the extent to which root cementum has to be removed during root surface instrumentation over and above that of the debridement of plaque and calculus. Similarly, the amount of tooth material removed by individual instruments is also unclear, but a trend towards less damaging methods of root surface debridement has evolved in recent years. The purpose of this in vitro study was to determine the amounts of root substance removed by 4 different methods of instrumentation, hand curette, ultrasonic scaler, airscaler and fine grit diamond bur. Measurement of tooth substance loss was carried out with a specially constructed measuring device at 360 sites on 90 mandibular incisors following 12 working strokes with a clinically appropriate force of application. Only a thin layer of root substance (11.6 microns) was removed by the ultrasonic scaler, compared to the much greater losses sustained with the airscaler (93.5 microns), the curette (108.9 microns) and the diamond bur (118.7 microns).

An in vivo model for the identification of serum proteins in the acquired subgingival pellicle

The present study describes an in vivo model for the collection of the subgingival pellicle adsorbed to tooth surface, and the identification of some serum proteins within this layer. Clean dentin slabs were prepared from freshly extracted teeth, and then placed subgingivally for 2 h. The dentin slabs with their adsorbed pellicle layer were processed for transmission electron microscopy. Thin sections were made from the specimens, and treated with antisera to human immunoglobulins and albumin. The reactions were visualized by means of protein A-gold complex, which allowed semiquantification of the serum proteins. The indicator proteins were all identified within the pellicle material, but their amounts and distribution varied. Albumin demonstrated higher amounts in the pellicle layer than other proteins, followed by IgA, IgG, and IgM in descending order. The model described seems useful for studying the acquired subgingival pellicle under varying degrees of disease and health.

Assessment of ultrasonic debridement of calculus-associated periodontally-involved root surfaces by the limulus amoebocyte lysate assay. An in vitro study

This investigation assessed the effectiveness of an in vitro ultrasonic debridement regime on periodontally involved teeth with visually-detectable calculus deposits, using the LAL assay for lipopolysaccharides (LPS) as a marker of bacterial products. 34 single rooted teeth with extensive amounts of calcified accretions were selected, of which 10 served as uninstrumented controls for the estimation of existing LPS levels. The periodontally involved roots of the 24 experimental teeth were debrided with a Cavitron TF-10 tip for a limited time using light pressure and overlapping strokes which ensured complete surface instrumentation without reference to the presence of calculus. Marked reductions in root surface area coverage by calculus were nevertheless achieved as assessed planimetrically from photographic records of the teeth before and after debridement. The root surfaces of each tooth were then stripped away and the harvested material subjected to 'Westphal' extraction and LAL assay for LPS. The resulting LPS yields from the experimental teeth ranged from less than 0.08 to 22.387 ng compared to 1,900 to 29,200 ng from the uninstrumented controls. The extremely small residual LPS yields from the experimental teeth not only confirm the efficacy of ultrasonic debridement but, when coupled with the lack of a relationship with the widely varying amounts of the remaining calculus, support the contention that bacterial plaque rather than calculus has the greater pathogenic potential. These results reinforce the growing impression of the superficial location of bacterial toxic products associated with periodontally involved root surfaces.

Effects of cavitational activity on the root surface of teeth during ultrasonic scaling

It is recognised that roughness of the root surface will occur during ultrasonic scaling and this has been attributed to the vibrating scaling tip. Although the presence of cavitational activity and acoustic microstreaming forces have been described their effects on the root surface have not been fully evaluated. Utilising an in vitro system of polished gold, it was possible to demonstrate an indentation produced by the scaling tip. However cavitational activity around the tip within the water supply appeared to produce an area of erosion (0.66 +/- 0.3 mm2, 1 SD, n = 10), and the surface appeared pitted. A scanning electron microscope study (SEM) of root surfaces following ultrasonic scaling showed similar areas of erosion. A replica technique was utilised so that control and experimental root surfaces could be observed. Cavitational activity and acoustic microstreaming resulted in a superficial removal of root surface constituents, and this area of removal was measured as 0.7 +/- 0.3 mm2 (1 SD, n = 10), which was not significantly different from that area observed with the gold surface system (p greater than 0.1). It may be concluded that cavitational activity within the cooling water supply of the ultrasonic scaler results in a superficial removal of root surface constituents.

Morphologic and histochemical characteristics of the dental cuticle in teeth affected by prepubertal periodontitis

A study was undertaken to determine the nature and composition of the cuticle found in teeth with generalized prepubertal periodontitis (PP). This was accomplished by using histological and histochemical methods on decalcified specimens. Forty-six permanent teeth which were extracted from three prepubertal periodontitis patients (siblings) were used. Nineteen of the 46 teeth were obtained with the facial or interdental gingiva. As a control, 20 healthy teeth extracted from 10 children for orthodontics reasons, and 22 teeth affected by terminal adult periodontitis (AP), were used. All the teeth with PP showed a thick coat covering the root surface from the cemento-enamel junction to the junctional epithelium. In some teeth the cuticle extended a few microns coronally to the cemento-enamel junction. The cuticle had a thickness which varied between 10 to 80 microns. It usually presented a very regular surface in the coronal portion of the root, and showed laminations suggesting appositional growth. In the middle and apical portions of the root exposed to the pocket, the cuticle was lobular with a very irregular surface and was covered with a thick microbial plaque. The staining reactions indicated that the cuticle was made of proteins probably derived from the inflammatory exudate. None of the healthy teeth examined nor those affected by AP showed a cuticle similar to those with PP. The cuticle formed on the teeth with PP appears to be an abnormal structure of proteinaceous nature, characteristic of these teeth, and may possibly play a role in the pathogenesis of the disease.

The effectiveness of root debridement in open flap procedures by means of a comparison between hand instruments and diamond burs. A SEM study

The goal of the present in vivo study was to evaluate human roots by means of scanning electron microscopy (SEM), after treating the root surfaces either with conventional hand instruments or with newly developed diamond burs. Peculiar root anatomy often makes perfect instrumentation with hand instruments difficult or impossible. On 20 teeth destined for extraction because of severe periodontitis, the root surfaces were exposed by mucoperiosteal flap procedures. Ten roots were then planed using fine curettes, and 10 were instrumented using diamond burs. Following extraction, the root surfaces were stained and photographed. Stained areas were examined by SEM. On the 20 test teeth, 79 surfaces were evaluated. From these, 381 stained zones were checked by SEM for the presence of bacteria. A total of 216 stained areas from teeth treated by hand instruments was evaluated; 15 of these (6.9%) contained bacteria. Of roots treated by diamond burs, 165 stained areas were evaluated; 9 (5.5%) exhibited bacteria. Thus, both methods resulted in root surfaces that were essentially bacteria-free.

Ultrastructural observations on bacterial invasion in cementum and radicular dentin of periodontally diseased human teeth

In this study the bacterial invasion in root cementum and radicular dentin of periodontally diseased, caries-free human teeth was examined. In addition, structural changes in these tissues, which could be related to the bacterial invasion, were reported. Twenty-one caries-free human teeth with extensive periodontal attachment loss were studied by light and scanning electron microscopy. At the base of the gingival pocket, bacteria were found in the spaces between remnants of Sharpey's fibers and their point of insertion in the cementum. In teeth that had been scaled and root planed, most of the root cementum had been removed. Bacterial invasion was found in the remaining root cementum. The invasion seemed to start as a localized process, often involving only one bacterium. In other areas bacteria were present in lacunar defects in the cementum. These lacunae extended into the radicular dentin. In 11 teeth bacteria had invaded the dentinal tubules. Most bacteria were located in the outer 300 microns of the dentinal tubules, although occasionally they were found in deeper parts. In two of the nontreated teeth, bacteria were detected on the pulpal wall. No correlation was found between the presence of bacterial invasion and the absence of radicular cementum. No bacteria were found in the portion of the root located apically to the epithelial attachment. These data are in agreement with our results from cultural studies of the bacterial flora in these structures. It was also demonstrated that in spite of meticulous scaling and root planning and personal oral hygiene, bacterial plaque remained present on radicular surfaces. Both the invaded dentinal tubules and the lacunae could act as bacterial reservoirs from which recolonization of treated root surfaces occurs. From these reservoirs bacteria could also induce pulpal pathoses. Since these bacterial reservoirs are not eliminated by conventional mechanical periodontal treatment, it seems appropriate to combine mechanical periodontal therapy with the use of chemotherapeutic agents.

Role of "diseased" root cementum in healing following treatment of periodontal disease. A clinical study

This clinical trial was undertaken to examine whether root debridement in the treatment of periodontal disease must include the removal of the exposed cementum in order to achieve periodontal health. The study included 11 adult patients with moderate to advanced periodontal disease. In a split-mouth design, the dentition of each patient was by random selection divided into test- and control quadrants comprising the incisors, canines and premolars. Following a baseline examination, all patients were given a case presentation and a detailed instruction in self-performed oral hygiene measures. The patients were then subjected to periodontal surgery. Following reverse bevel incisions, buccal and lingual mucoperiosteal flaps were elevated and all granulation tissue was removed. In 2 jaw quadrants (control quadrants) in each patient, the denuded root surfaces were carefully scaled and planed in order to remove soft and hard deposits as well as all cementum, using hand instruments and flame-formed diamond stones. In the contralateral quadrants (test quadrants) the roots were not scaled and planed but soft microbial deposits were removed by polishing the root surfaces with the but soft microbial deposits were removed by polishing the root surfaces with the use of rubber cups, interdental rubber tips and a polishing paste. Calculus in the test quadrants was removed by the use of a curette, but precaution was taken to avoid the removal of cementum. The flaps were repositioned to their original level and sutured. The patients were following active treatment enrolled in a supervised maintenance care program including "professional tooth cleaning" once every 2 weeks for a 3-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Scanning electron microscopy observations of initial clot formation on treated root surfaces

This study presents the morphological sequence of events in initial blood clot formation on various root surfaces of freshly extracted human teeth. Four teeth with periodontal disease (PD) and three teeth without PD were extracted and the roots sectioned into halves. Those root surfaces with PD had four treatment areas: (1) intact periodontal ligament (PDL), (2) unplanned PD, (3) PD plus planed, (4) PD plus planed plus application of pH 1 citric acid (CA). The roots with no PD had three treatment areas: (1) intact PDL, (2) planed, (3) planed plus CA. Both root halves were reinserted together into the original extraction site. Each root half was then removed at either zero, one, two or four minutes and prepared for scanning electron microscope (SEM) evaluation. SEM observations suggested that plasma proteins were deposited initially on all root surfaces. Platelets and erythrocytes enmeshed in fibrin deposited most rapidly and consistently over the plasma protein layer where intact PDL was present. Similar observations were noted on the planed plus CA surfaces and appeared to occur at an earlier time than on the planed-only surfaces. A constant feature at all time periods was the absence of organized clot formation over the plaque-free zone of the PD root surfaces. By two minutes all surfaces, except the plaque-free zone of the PD area, appeared to have clot lysis occurring. While clot formation appeared to occur more rapidly over surfaces in the non-PD roots, no marked morphological differences in clot formation were observed between PD and non-PD teeth with similar root surface treatments.

Bacterial invasion in root cementum and radicular dentin of periodontally diseased teeth in humans. A reservoir of periodontopathic bacteria

In this study the viability and the distribution of bacteria within the radicular dentin and pulp of periodontally diseased caries-free teeth were studied. Healthy teeth served as controls. Samples were obtained from the pulp tissue and from the radicular dentin. Dentin samples were taken from the interdental surfaces in the subgingival area. Starting from the pulpal side, three to five successive dentin layers of approximately 1 mm thickness were sampled. The samples were processed and cultured using an anaerobic technique. Bacterial growth was detected in 87% of the periodontally diseased teeth. In 83% of the teeth, bacteria were present in at least one of the dentin layers. Fifty-nine percent of the diseased teeth, from which the pulp tissue was cultured, contained bacteria in the pulp samples. The mean bacterial concentrations in the pulp and dentin layers ranged from 1,399 to 16,537 colony-forming units (CFU) per mg of tissue. These concentrations were 259 to 7,190 times greater than concentrations found in healthy teeth. It is suggested that the roots of periodontally diseased teeth could act as bacterial reservoirs from which recolonization of mechanically treated root surfaces can occur, as well as infection of the dental pulp. These findings might change current concepts concerning root surface debridement in periodontal therapy.

Evaluation of the effect on root surfaces of air turbine scalers and ultrasonic instrumentation

Three air turbine scalers were compared to each other and to an ultrasonic instrument (CAVITRON) on medium and maximum power setting. The amount of remaining calculus, roughness and loss of tooth substance were estimated by means of well-defined index systems (RCI and RLTSI). The time required to clean the test surfaces--marked on proximal root surfaces of mandibular incisors--was also noted. Standardized scanning electron microscope (SEM) micrographs were independently "blind-scored" by three examiners, and total mean scores were calculated. The results revealed significant differences (P less than 0.001) between the instruments with respect to the amount of remaining calculus. There were also significant differences (P less than 0.05) between roughness and loss of tooth substance produced by CAVITRON at maximum power setting and that produced by the other instruments. No differences were found with regard to the time required to clean the test surface (until visually clean).