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Biomedical subjects

T Lie

Publications and source records attributed to T Lie.

At least 19 recordsLinked to original sources
PubMed1992

Comparative in vitro studies of sonic, ultrasonic and reciprocating scaling instruments.

Flat root surface areas of formalin-stored mandibular incisors with plaque and calculus were scaled by sonic (PHATELUS SONIC SCALER, SONIC FLEX 2000, TITAN-S SONIC SCALER) or ultrasonic instruments (HYGIENIST ULTRASONIC SCALER, CAVITRON) or by a new reciprocating scaling insert for the EVA/PROFIN system. The test areas were photographed by SEM and coded micrographs were independently graded by three examiners using the RCI (Remaining Calculus Index) and the RLTSI (Roughness Loss of Tooth Substance Index). The findings revealed that the sonic scalers as a group removed calculus more completely but also left significantly more roughness and loss of tooth substance than the other instruments tested. No difference was seen between the two ultrasonic scalers. The reciprocating insert gave results similar to those of the ultrasonic except for the scaling time which was significantly longer for the new "cleansing principle".

Dental Calculus↗
PubMed1992

Clinical responses to subgingival application of a metronidazole 25% gel compared to the effect of subgingival scaling in adult periodontitis.

A newly developed metronidazole 25% dental gel was compared with subgingival scaling in the treatment of adult periodontitis. 206 patients in 9 centres participated in the study. Probing pocket depth (PPD) and bleeding on probing (BOP) were recorded before treatment and 2, 6, 12, 18, and 24 weeks after the treatment. All patients had at least 1 tooth in each quadrant with a PPD of 5 mm or more. The treatments consisted of 2 applications of dental gel (days 0 and 7) in 2 randomly selected quadrants (split mouth design) and 2 sessions of subgingival scaling (1 quadrant on day 0, and 1 quadrant on day 7). Instruction in oral hygiene was given 2 weeks after completed treatment. The average PPD and the average frequency of BOP were calculated over all sites with initial PPD of 5 mm or more. PPD and BOP were thus, at each examination, calculated from the same sites. The mean PPD was 5.9 mm before gel application and 5.8 mm before scaling (p = 0.31). BOP was 88% in both treatment groups. 24 weeks after the treatment, PPD and BOP were significantly reduced in both groups and for both parameters (p < 0.01). PPD was reduced by 1.3 mm after gel application and 1.5 mm after scaling; BOP was reduced by 32% and 39%, respectively. The difference between the treatments was statistically significantly, but considered as clinically unimportant.

Adult↗
PubMed1992

The effect of hygiene instruments on dentin surfaces: scanning electron microscopic observations.

The present study consists of two separate parts. The first section is an in vitro evaluation of the relative abrasiveness of some hygiene instrumentations commonly used during maintenance therapy. In the second section, one of the instruments, a recently developed plastic tip for use on a sonic scaler, was examined for its ability to remove dental plaque from root surface specimens instead for 5 weeks in the oral cavities of dogs. The in vitro study was performed on recently obtained dentin specimens where a ridge had been machined parallel to the long axis of the tooth. The sonic scaler fitted with the plastic tip gave considerably less removal of dentin and a smoother dentin surface than the curet, the rubber cup with polishing paste, or the sonic scaler with an ordinary metal tip. These findings further demonstrated that the plastic tip was able to efficiently remove 5-week old dental plaque from experimental root surface areas within a time frame of 5 seconds. The new plastic tip may be valuable in maintenance therapy giving less risks for iatrogenic effects on the root surfaces than other debridement methods.

Alloys↗
PubMed1992

Cemental tear related to rapid periodontal breakdown: a case report.

Cemental tears have been described both in exposed and unexposed cementum. The phenomenon is believed to be elicited by overloading or acute trauma from occlusion. In this case report a patient, with a history of periodontal health, presented with an acute periodontal lesion on the distal aspect of a bridge abutment tooth. Periapical radiographs demonstrated an extensive vertical intrabony defect adjacent to the vital abutment tooth containing a radiopaque "foreign body." Histological examination of the surgically removed "foreign body" revealed a piece of dental cementum with some attached soft tissue. The lesion responded well to a surgical approach. Healing was uneventful and periodontal health was restored. This case illustrates that cemental tear should be considered as a differential diagnostic entity in isolated sites with rapid periodontal breakdown.

Aged↗
PubMed1992

Root dentin morphology after different modes of citric acid and tetracycline hydrochloride conditioning.

The purpose of this study was to assess the effect of citric acid and tetracycline HCl application to dentin surfaces by a "passive dripping" or an "active burnishing" technique. Twenty dentin blocks were prepared from freshly extracted non-diseased human impacted third molars. The blocks were root planed and randomly assigned to two groups for treatment with either citric acid or tetracycline HCl. The duration of treatment was 30, 60, 120, or 240 seconds. Control blocks were treated with distilled water. After treatment the blocks were processed for observation and measurements in the scanning electron microscope (SEM). Application of either of the acid solutions resulted in removal of the smear layer. Measurements indicated a time dependent increase in the mean dentinal tubule orifice diameter ranging from 1.05 microns in control specimens to 3.18 microns after 4 minutes treatment (citric acid group). The increase in tubule diameter was significantly greater (P less than or equal to 0.01) for both citric acid treatment modalities than tetracycline HCl treatment. There was also a time dependent increase in the depth of penetration as measured by a trumpeting of the tubule profiles, and this penetration was significantly greater (P less than or equal to 0.01) after citric acid treatments. Passive or active application of the acids did not seem to have any major impact on the measurements or on the surface morphology. It was concluded that citric acid causes more extensive changes than tetracycline HCl and that the mode of application of the agent is probably not critical.

Acid Etching, Dental↗
PubMed1992

Relative production of IL-1 beta and TNF alpha by mononuclear cells after exposure to dental implants.

Interleukin-1 (also known as osteoclast activating factor, OAF) is a cytokine produced primarily by monocytes and macrophages and is thought to mediate many of the immunologic, metabolic, and endocrine alterations seen with microbial infection, tissue injury, inflammatory disease, and bone loss. Stimuli for IL-1 production include microorganisms, endotoxins (LPS), antigen-antibody complexes, clotting components, and other cytokines. The purpose of this study was to determine whether dental implants stimulated peripheral blood mononuclear cells (PBMCs) to produce IL-1 beta (OAF) as well as tumor necrosis factor (TNF alpha). This production may lead to bone loss or failure of an implant. Three duplicates of five different implants were incubated with 2 x 10(6) PBMCs/ml in 20% autologous serum; the esterase positive PBMCs amounted to 14.5%. Measured by radioimmunoassay techniques and compared to controls, all of the implants except one caused significant in vitro generation of IL-1 beta and TNF alpha. The stimulation of IL-1 beta/TNF alpha production by these materials suggests that they are not physiologically inert and that the IL-1 beta (OAF) production may contribute to a less favorable osseoadaptation. OAF has a physiologic (homeostatic) role in maintenance and alteration of osseous structures, but the level at which physiologic becomes pathologic is unknown. Although there were statistical differences between the cellular response to these implants, the clinical significance of the differences remains to be determined.

Cells, Cultured↗
PubMed1992

Early effects of periodontal therapy on the detection frequency of four putative periodontal pathogens in adults.

This study aimed to examine early posttreatment changes in the periodontal microflora. Paper point sampling and conventional bacterial cultivation were used to monitor the effects of surgical and non-surgical periodontal therapy on the detection frequency of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and Capnocytophaga species in deep periodontal pockets. Ten patients, 5 men and 5 women (mean age 44 years), with advanced periodontal disease were selected from the dental school patient population for the study. A total of 245 teeth in 10 defined areas of the dentition were treated by oral hygiene instruction followed by scaling and root planing alone (121 sites) or with surgical interventions (124 sites). Ninety sites, 47 surgical and 43 non-surgical, with initial pocket depth greater than or equal to 6 mm were sampled at baseline and 3 months after completion of therapy. Treatment by both procedures resulted in significant clinical improvements as assessed by all clinical parameters used. Baseline results may indicate that the level of P. gingivalis was reduced in the presence of P. intermedia, while A. actinomycetemcomitans seemed to be reduced in the presence of P. gingivalis and/or P. intermedia. Three months after therapy, the detection frequency of P. gingivalis was significantly reduced (P less than 0.05) in surgical and non-surgical sites while the reduction for P. intermedia was significant only for surgical sites (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Periodontal surgery for the maxillary anterior area.

A modified surgical technique, aimed at the conservation of maxillary anterior esthetics, has been proposed for the treatment of maxillary anterior periodontal pathoses that do not respond to traditional, nonsurgical approaches. The modified resective technique gives selective access to the periodontally diseased root surfaces while allowing the periodontist to avoid facial areas with shallow pockets. This paper describes the technique in detail and discusses its indications, advantages, and disadvantages.

Follow-Up Studies↗
PubMed1979

Replica study of plaque formation on human tooth surfaces.

Plaque formation on buccal tooth surfaces was studied by replica technique, consisting of impressions using low viscosity silicone impression materials and positive models produced in epoxy resins. Bacterial accumulation occurred near the cemento-enamel junction in 6-hr specimens, and subsequently expanded in a coronal direction. This development took place partly by extensions of single layers of bacteria, and partly by a pattern where the colonization was mostly restricted to vertical enamel cracks. Plaque accumulations were also frequently located in abrasion grooves and surface pits in the enamel, and prolific plaque areas were consistently surrounded by a monolayer of bacterial cells. Globular and hemispheric structures which occurred, especially on root surfaces immediately after cleaning, were probably artefacts caused by air bubbles or remaining moisture. In separate series of experiments it was demonstrated that improved reproduction of details from the plaque could be achieved by repeating the replicating procedure. The findings indicate that plaque formation starts by adsorption and proliferation of individual bacteria on tooth surfaces, and not by adsorption of aggregates of cells. Special attention should be directed against the problem of artefacts and moisture in replica studies of dental plaque.

Dental Impression Materials↗
PubMed1979

Morphologic studies on dental plaque formation.

The present summary and the following papers (I--VII) are submitted in partial fulfillment of the requirements for the degree of Doctor Odontologiae at the University of Bergen. 1: Growth of dental plaque on hydroxyapatite splints. A method of studying early plaque morphology. J. Periodontal Res. 1974, 9, 135--146. II: Pellicle formation on hydroxyapatite splints attached to the human dentition: Morphologic confirmation of the concept of adsorption. Arch. Oral Biol. 1975, 20, 739-742. III: Scanning and transmission electron microscope study of pellicle morphogenesis. Scand. J. Dent. Res. 1977, 85, 217-231. IV: Early dental plaque morphogenesis. A scanning electron microscope study using the hydorxyapatite splint model and a low-sucrose diet. J. Periodontal Res. 1977, 12, 73-89. V: Ultrastructural study of early dental plaque formation. J. Periodontal Res. 1978, 13, 391-409. VI: Dental plaque morphology as revealed by direct observation and by replicating techniques. Acta Odontol. Scand. 1978, 36, 279-288 Co-author: F. Gusberti. VII: Replica study of plaque formation on human tooth surfaces. Acta Odontol. Scand. 1979, 37, 65-72. Co-author: F. Gusberti. These papers are referred to as I-VII in the present summary. Other papers are referred to in conventional manner.

Dental Impression Technique↗
PubMed1978

Dental plaque morphology as revealed by direct observation and by replicating techniques.

The ability of four elastomer impression materials to reproduce details of bacterial plaque structures was studied by comparing areas of the replica models with corresponding areas of the replicated plaque. Plaque was grown on hydroxyapatite splint segments for 48 hours and replica models were made from three different resins. One of the resins, a methacrylate material, was not suited for this purpose due to its content of spherical particles. The polysulfide and polyether impression materials reacted with the heat curing epoxy resin, and less satisfactory results were obtained with cold curing epoxy resin. Best results were obtained by a combined use of low viscosity silicone impression materials and cold or heat curing epoxy resins as model materials. However, a considerable loss of detail occurred in the replica models compared with observations of plaque directly on splint surfaces. Outlines of individual bacteria could sometimes be seen in the models, but generally several cells seemed to fuse, and appeared like small globular structures where cells and pellicle were difficult to distinguish. The bacterial colonization started near the gingival border of the surface, initiated by attachment of individual bacteria to the pellicle surface.

Dental Impression Materials↗
PubMed1977

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.

Dental Calculus↗
PubMed1977

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.

Curettage↗
PubMed1977

Scanning and transmission electron microscope study of pellicle morphogenesis.

The morphology of pellicle formation was studied using correlated transmission and scanning electron microscopy. Pellicle developed on hydroxyapatite/epoxy resin splints attached to the buccal surfaces of molars and premolars in six young individuals. Splint segments were removed at intervals of 2, 4, 6, 12, 24, and 48 h. Measurements of pellicle thickness revealed that during the first 12 h considerably more material formed on the apatite surfaces than on the epoxy resin areas of the splints. This difference was equalized in 24- and 48-h specimens. Three types of pellicles could be distinguished on the basis of morphologic criteria. A globular pellicle, characterized by a consistent presence of globules of varying size and configuration, seemed to predominate in most subjects. These globules could not be mistaken for bacteria due to their dimensions, contour, and lack of cell walls. A fibrillar pellicle consisted of 3- to 7-nm-wide fibrils and frequently included some finely globular particles. A granular pellicle displayed a relatively even surface contour and did not exhibit globular or fibrillar structures. In contrast to the two other types, the granular pellicle contained distinct laminations. Apparently, the varying morphology of the early pellicle is a reflection of its complex chemical composition.

Dental Pellicle↗
PubMed1975

Formation of an experimental dental cuticle.

Slices of dental enamel, cementum and dentin, and segments of epoxy resin splints with exposed synthetic hydroxyapatite crystals were incubated in human serum overnight. Observations by light and electron microscopy revealed that a cuticular structure with staining reactions and ultrastructural appearance similar to those of dental cuticle had formed on the various surfaces. The results support the hypothesis that the dental cuticle in vivo may consist of serum components which have been adsorbed to the tooth surface as a result of gingival exudation.

Dental Enamel↗