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Biomedical subjects

P Gaengler

Publications and source records attributed to P Gaengler.

At least 19 recordsLinked to original sources
PubMed2004

Micromorphological evaluation of posterior composite restorations - a 10-year report.

The summarized scanning electron microscopic-supported micromorphologic data of a 10-year longitudinal clinical study of GIC/Hybrid composite posterior restorations is reported. The aim of this study was to compare the results to USPHS-compatible clinical criteria of the CPM index and to analyse the deterioration pattern and the success rate. Out of a total of 194 Class I and Class II fillings 46 restorations were at baseline, after 1, 3, 5, 7 and 10 years. The restorations were micromorphologically examined using gold-sputtered replicas and coded according to the M-criteria of the CPM index. The features for surface roughness, surface texture, marginal integrity, excess of material, marginal fracture, loss of material, marginal leakage and other filling imperfections were assessed. Eighteen fillings showed perfect margins, rapidly deteriorating after the first year of service. Despite poor micromorphologic marginal conditions all restorations retained optimal functional characteristics. Parallel longitudinal micromorphologic and clinical assessment of posterior GIC/Composite restorations revealed fine structure and deterioration patterns of the tooth-biomaterial interface. The layer-technique using GIC as dentine replacement and resin-based composite as enamel replacement results, according to previous biocompatibility testing, and clinical data, in optimal pulp protection and correct anatomic form over a 10-year period. The myth of the need for perfect marginal integrity requires further discussion.

Adolescent↗
PubMed2003

Volumetric assessment and quantitative element analysis of the effect of fluoridated milk on enamel demineralization.

OBJECTIVES: It was the purpose of this study to investigate the effect of milk and fluoridated milk on experimentally induced caries-like-lesions. MATERIALS AND METHODS: Twelve extracted impacted human molars were covered with wax leaving two 3 mm x 3 mm windows on the buccal and lingual surfaces and incubated alternating in demineralizing solution at pH 4.85 and in milk, F-milk, saline, and remineralizing solution, respectively. Afterwards serial ground sections were cut and investigated by polarization-light-microscopy (PLM) and SEM using EDX element analysis. RESULTS: The results showed increased thickness of the superficial layer in the F-milk samples. Quantitative element analysis revealed a significant increase in the fluoride content of the superficial layer and of the body of the lesion of the F-milk group. The body of the lesion of the F-milk group was less demineralized than in the other groups. CONCLUSION: From the results we conclude, that the parallel investigation by PLM, SEM combined with EDX quantitative element analysis is a powerful method to assess caries-like-lesion formation and that fluoridated milk has protective properties in inhibiting demineralization.

Animals↗
PubMed2003

Morphological analysis and chemical content of natural dentin carious lesion zones.

Dentin is one of the earliest bio-mineralization products to appear in the evolution of vertebrates. Dentin reactions to infection mimic earlier phylogenetic patterns, and carious lesions are divided into different zones which reflect the natural patho-morphological reaction of dentin to the carious attack. It was the aim of this study to investigate deep dentin carious lesions of human molars with combined polarization light microscopy, scanning electron microscopy and energy dispersive X-ray element analysis (EDX) for the determination of different zones of the carious lesions, their extent and the chemical content. Sixteen extracted teeth with deep dentin carious lesions were embedded in Technovit 9100 (Kulzer) and serial sections of 80 microm thickness were made. These sections were then examined with polarized light microscopy to identify the different zones of the lesions. The outlines of the zones were traced consecutively and 3D-reconstructions were made for the determination of the extent and calculation of the volumes of the different zones. From the volumes of the demineralizing dentin and the translucent zone a Dentin Demineralization Index (DDI) was calculated. Three sections of each lesion were then coated with carbon and studied with a scanning electron microscope. 3D-reconstruction of the teeth showed the rather stable translucent zone, interrupted by remnants of dead tracts, and very different volumes of demineralizing dentin. Therefore, with increasing size of the demineralizing dentin, the DDI increased. The chemical content was measured using energy dispersive X-ray analysis (EDX) in areas of intertubular dentin. The content of Ca, P, and C was significantly different in all zones. The Ca/P ratio was significantly different between sound dentin and demineralizing dentin. From the results we conclude that the mineral content of intertubular dentin of the translucent zone and demineralizing dentin is different from that of sound dentin, and the unique mineralization pattern of the translucent zone is a biological reaction to the carious attack. Because active dentin lesions exhibit many non-occluded open dentin tubules, further bacterial invasion or, in case of dentin treatment, the penetration of bonding agents towards the pulp is morphologically not prevented and therefore of clinical importance.

Dental Caries↗
PubMed2002

Secondary caries susceptibility of teeth with long-term performing composite restorations.

The aim of this study was to assess retrospectively the caries susceptibility of posterior teeth with composite restorations after 18 and 20 years. The sample was selected out of the recall of a dental office. Sixteen restorations were reassessed after 18 and 20 years. All findings have been rated according to the C criteria of the CPM index. For the micromorphological evaluation with SEM, replicas were made using a two-step impression technique. All restorations demonstrated marginal imperfections and a predominant rough surface. At the 18 year-evaluation two restorations exhibited secondary caries. Despite of extended marginal gap formations none of the 12 restorations reexamined at 20 years showed secondary caries. Direct composite restorations can serve over a long period of time despite of poor qualitative parameters. Micromorphological marginal deterioration and clinical gap formation do not necessarily result in a higher risk for secondary caries.

Composite Resins↗
PubMed2002

Utilisation of dental services among a Turkish population in Witten, Germany.

AIM: To describe the oral health status and the dental service use pattern of a Turkish population in Witten, Germany, and to assess the factors affecting this use pattern. DESIGN: Cross-sectional. PARTICIPANTS: 532 Turkish people older than 12 years. METHODS: The data were obtained through a structured questionnaire and oral examination. The World Health Organisation methodology was followed in assessing the oral health status. RESULTS: Comparison of the study population with German studies showed a similar caries experience in younger groups, but in older groups a lower treatment level. The proportion of regular dental attendees indicated no difference according to age. A person was more likely to use dental services regularly if he had a better level of German language and preferred German services. Perceived oral condition, educational level and sex were also important for care pattern. Regular use of services was negatively associated with the mean number of decayed, missing and periodontally involved teeth, but positively related to the number of filled teeth. CONCLUSIONS: Since factors reflecting the level of adaptation to Germany were also important determinants of the dental utilisation pattern, efforts to improve the utilisation of services should be based on the socio-educational development of Turkish people in Germany.

Adolescent↗
PubMed2001

Qualitative and quantitative assessment of intratubular dentin formation in human natural carious lesions.

It was the aim of this study to investigate the scanning electron microscopy (SEM) features and the element content of calcium (Ca) phosphorus (P), magnesium (Mg), oxygen (O), and carbon (C) of sound dentin, demineralized dentin, secondary dentin, intratubular and peritubular de novo dentin formation due to caries progression and to compare the element content with chemically pure hydroxyapatite. Eighteen extracted teeth with deep dentin carious lesions were embedded in Technovit 9100 (Kulzer), and serial sections of 80 microm thickness were made. These sections were then investigated with polarized light microscopy to identify the lesions. Two sections of each lesion were then coated with carbon and studied with a scanning electron microscope. Of the 18 teeth, 8 showed intratubular dentin formation. The element content was measured using energy dispersive X-ray analysis (EDX). About 75% of all involved dentin tubules showed intratubular de novo dentin formation. The Ca/P ratio in sound dentin, demineralized dentin, peritubular dentin, and secondary dentin was within the range of hydroxyapatite, whereas in intratubular dentin the Ca/P ratio was different than that of hydroxyapatite. The element content for Ca was statistically highly significantly different (P < 0.01) among sound dentin/intratubular dentin, sound dentin/peritubular dentin, and sound dentin/ secondary dentin, but not between sound dentin/ demineralized dentin and sound dentin/hydroxyapatite. For the other measured elements varying statistical differences were found. Our results indicate that intratubular dentin does not occlude the dentin tubules completely and mineralizes different than that of sound dentin and may therefore not be true hydroxyapatite.

Dental Caries↗
PubMed2001

Induction and 3D reconstruction of caries-like lesions in an experimental dental plaque biofilm model.

The aim of this study was to examine an in vitro dental plaque model for volumetric assessment and 3D reconstruction of experimentally bacterial induced caries-like lesions. Twenty-three extracted, impacted human molars were coated with a varnish leaving a 3 x 3 mm window on the smooth surface. The teeth were coated with human saliva and Streptococcus sobrinus 6715 adhered onto the enamel via a sucrose dependent mechanism. The coated teeth were incubated for 1, 7, 14 and 28 days. At the end of each incubation period microhardness was measured on three sectioned teeth of each incubation period at the enamel surface and at 450 and 750 microm depth perpendicular to the enamel surface. The enamel surface was investigated by scanning electron microscopy (SEM) prior to embedding and serial sectioning of 12 other teeth. The serial sections were studied with polarization light microscopy to investigate subsurface demineralization. The outlines of the caries-like lesions were then traced consecutively on transparencies, digitized and three-dimensionally reconstructed to demonstrate the expansion of the lesion into enamel for volumetric assessment. Microhardness was significantly reduced on the enamel surface after 7, 14 and 28 days incubation. The SEM investigation showed a surface demineralization with dissolution of the prism cores after 28 days incubation. Polarization light microscopy demonstrated caries-like lesions with an irregular expansion into enamel. The results demonstrate that the described method produces caries-like lesions which can be used for further experimental studies regarding demineralization and remineralization processes.

Biofilms↗
PubMed2001

Clinical evaluation of posterior composite restorations: the 10-year report.

PURPOSE: To summarize all clinically relevant data of a 10-year prospective evaluation of posterior glass-ionomer cement/composite restorations (Ketac Bond/Visio-Molar radiopaque). MATERIAL AND METHODS: For this study 194 hybrid composite fillings (115 Class I, 79 Class II) were applied in 73 adult patients. The exposed dentin was covered with glass-ionomer cement. The clinical evaluation was carried out at baseline, after 6 months and at 1-year intervals up to 10 years. The USPHS-compatible CPM Index was used with the C and P criteria presented here for anatomic form, color match, surface quality, wear, marginal integrity, marginal ledge, marginal discoloration, secondary caries, and clinical acceptability. Thermal and electrical sensitivity testing were recorded annually. RESULTS: At baseline, 194 restorations were rated. The drop-out of patients comprised 108 fillings after 10 years. During this time, 24 restorations could not be followed up because of new carious lesions at different sites and/or prosthodontic treatment (drop-out of teeth). Forty-six composite restorations were longitudinally controlled over 10 years, and 16 more fillings failed before the end of the study (3 filling fractures, 7 partial filling losses, 1 total filling loss, 5 cases of secondary caries). Only Class II composite restorations exhibited secondary caries (4 fillings after 7 years and 1 filling after 9 years). After 10 years, the correct anatomic form was preserved in 44 fillings, but all restorations showed rough surface and wear. The majority of restorations (26 fillings) was free of marginal discoloration, and the color match showed only 3 fillings being too dark. The marginal integrity was optimal at baseline and during the first year. During the second year a continuing degradation started and lasted until the end of the study. Thirteen restorations showed optimal marginal integrity after 10 years. CONCLUSION: The USPHS-compatible CPM Index represents a sensitive rating system for long-term observation of posterior composite restorations. The early risk of failure is attributed to bulk fractures and partial loss of filling material. The longevity over 10 years is a maximum of 74.2%, and the very low secondary caries rate and the high percentage of correct anatomical form confirm the clinical safety of posterior composite restorations.

Adolescent↗
PubMed2000

Distribution and volumetric assessment of initial approximal caries lesions in human premolars and permanent molars using computer-aided three-dimensional reconstruction.

Serial sections from 21 extracted premolars and permanent molars, divided into three age groups (group 1, 10-19 years; group 2, 20-39 years; group 3, 50-69 years.), were viewed by polarized light microscopy for reconstruction of the caries lesions. The volumes of the lesional body and the transparent zone, and the volumes of early dentinal lesions were calculated; and an enamel demineralization index (EDI) and an enamel-dentine demineralization index (EDDI), representing the volumetric ratio of the body of the lesion to the translucent zone, and the body of the lesion to the volume of the early dentinal lesion, respectively, were determined. The method showed that there are three typical sites of individual initial caries lesions at the approximal surface: within the contact area, in the subcontact area, and in the cervical area. Volumetric assessment demonstrated a larger volume of the body of the lesion in older teeth with a smaller volume of the translucent zone relative to the lesional body. From these results it can be concluded that there are usually more than one individual initial caries lesions at the approximal tooth surface. Calculation of demineralization indices demonstrated different features for small lesions with pronounced transparent zones and for large lesions with small transparent zones. The computer-assisted three-dimensional reconstruction technique and the volumetric assessment are of value in investigations of the micromorphology and progression of natural caries lesions in permanent teeth.

Adolescent↗
PubMed2000

Pulp reactions to different preparation techniques on teeth exhibiting periodontal disease.

To evaluate the histopathological outcome of two preparation techniques (featheredge preparation/shoulder preparation) on teeth exhibiting pulp reactions due to age and periodontal disease, 11 teeth were prepared for full veneer crowns. Laboratory made resin crowns were fixed with a zinc phosphate cement for a period of 90 days. After extraction, adjacent pulpal areas were histopathologically rated according to the BRD criteria comprising the parameters (i) Bacterial invasion, (ii) Regenerative parameters, (iii) Degenerative parameters. Degenerative reactions were more correlated with tooth preparation than with advanced periodontal disease. The severity of endondontal reactions depends more on remaining dentin thickness than on the type of preparation.

Acrylic Resins↗
PubMed1998

Three-dimensional reconstruction of approximal subsurface caries lesions in deciduous molars.

The present study examines the three-dimensional (3D) morphology of early approximal subsurface enamel caries lesions and subjacent dentin reactions in deciduous molars. Twenty-three extracted primary molars were embedded in Technovit 9100 and serial sections were cut using a saw microtome. Forty approximal lesions were found and investigated using polarized light microscopy for the identification of the different zones of the caries lesion. These zones were then reconstructed three-dimensionally using computer-aided 3D reconstruction methods and the dimensions and volumes of the translucent zone, the body of the lesion, and the dentin lesion were calculated. The enamel demineralization index was defined as the ratio between the translucent zone and the body of the lesion, whereas the enamel-dentin demineralization index was defined as the volumetric ratio of the early dentin lesion to the body of the enamel lesion. The 3D reconstruction of the lesions showed extremely heterogeneous micromorphological features of zone profiles. In enamel lesions, the results demonstrated a decreasing enamel demineralization index with increasing size of the lesion, which indicates a high risk of further caries progression. The enamel-dentin demineralization index indicated, in 5 out of 17 dentin lesions, a high risk of further caries progression. Computer-assisted 3D reconstruction and volumetric assessment of initial caries lesions in deciduous molars represents a valuable methodology in pathogenesis studies, which may lead to a better clinical understanding of caries progression.

Dental Caries↗
PubMed1996

Periradicular curettage.

Periradicular curettage is a part of the treatment procedure of periradicular surgery. Its main purpose is to remove pathological periradicular tissues for visibility and accessibility to facilitate the treatment of the apical root canal system, or sometimes for the removal of harmful foreign materials present in the periradicular area. Inflammatory periradicular lesions (granuloma and cysts) are the responses of the periradicular tissues to irritants from the root canal and not from the periradicular area unless medicaments and/or filling materials have been forced through the apical foramina or perforations into the periodontium. Histologically, the inflammatory periradicular lesion is similar to healing granulation tissue, which is composed of cells which have natural and specific immunological defence capability and cooperate by means of cytokines to amplify the protective mechanisms of the host. Accordingly, it is not necessary to completely curette out all the inflamed periradicular tissues during surgery, since this granulation-like tissue will be incorporated into the new granulation tissue as part of the healing process. To control the source of irritants in the root canal is far more important than to remove all periradicular tissues affected by the irritants. The successful removal of all irritants from the root canal system results in resolution of pulpally induced periradicular lesions. In the case where the periradicular lesion is caused by endodontic instruments or cytotoxic filling materials placed in the periradicular tissues, removal of these foreign objects is required for resolution of the lesion.

Animals↗
PubMed1996

Clinical and pathomorphological investigation of spontaneously occurring periodontal disease in dogs.

Diagnostic evaluation of, and treatment planning for, different periodontal diseases of dogs are a common problem in veterinary dentistry. Therefore the aim of the present study was to propose a classification for inflammatory periodontal disease. One hundred and twenty-three male and female poodles (from two to over 12 years) were used for the clinical investigations; 120 periodontitis teeth were analysed for pathomorphological signs of inflammation. The recorded data made it possible to differentiate five forms of gingivitis (gingivitis simplex, hyperplastica, ulcerosa, granulomatosa and desquamativa) and three forms of periodontitis (juvenile, rapidly progressive adult and chronic adult periodontitis). The pathomorphological investigations allowed a differentiation between acute progressive inflammation, chronic nonprogressive inflammation, chronic proliferative inflammation and chronic resorptive inflammation. It is concluded that standardised diagnoses as well as the pathomorphological background may be helpful tools for providing effective treatment-strategies.

Animals↗
PubMed1996

Epidemiology of periodontal disease in poodles.

The periodontal condition of 123 poodles was assessed using the parameters of depth of gum pocket, attachment level, bleeding on probing, and plaque and calculus accumulation. No dogs were free of periodontal disease. The number of deep pockets and dramatic loss of attachment ranged from 0.1 teeth in young dogs to 4.2 teeth in old animals. A sixfold increase in deep pocketing took place in dogs between the ages of six and seven, followed by a twofold increase in the number of teeth missing in dogs within the 10 to 11 year age group. First premolars, incisors and second molars were at highest risk. No correlation between dietary conditions and disease incidence could be detected. It is concluded that, by concentrating their diagnostic efforts on those age groups and types of teeth at highest risk, clinicians could improve the effectiveness of their treatment interventions.

Age Distribution↗
PubMed1996

Histobacteriology and pulp reactions to long-term dental restorations.

The prevention of degeneration and necrosis of the endodont is one of the main goals of dental treatment. Kerschbaum and Voss (1979, 1981) described that 15% of teeth showed negative results to sensitivity testing 10 years after crown preparation. Pulpal responses to dental treatment depend on many factors including thermal injury, transsection of the odontoblastic process, vibration, desiccation of dentin, pulp exposure, smear layer, remaining dentin thickness and used materials. The knowledge concerning endodontic reactions in short and medium term observation is mainly based on research by Klötzer and Langeland. Histological assessment of reactions is a well accepted method for biocompatibility testing (i.e. ISO/TR 7405). It is consistent to apply its principles to the evaluation of endodontic reactions of teeth with long term restorations. As pulpal injury is furthermore due to microleakage between filling material and the wall of the cavity the analysis of infected dentin tubules seems to be important. A consideration of the location of the tubules and of the severity of the invasion is necessary. Using a classification (grade 1-6) comprising the parameters of degenerative and regenerative reactions and bacterial invasion, 24 teeth restored with different types of fixed prosthodontic restorations were investigated. The restorations were between 0-6, 7-12 and 13-18 years in situ. Serial sections (5 microns) were stained with haematoxylin-eosin, azan, according to Goldner and J. Hopkins. 22 of 24 teeth showed typical degenerative reactions. Negative sensitivity testing occurred in teeth with no pain and no or partial necrosis. The histobacteriological assessment showed bacterial invasion of the dentin tubules of 21 teeth. From this investigation it was concluded that the proposed classification shows sufficient sensitivity for the evaluation of progressive endodontic changes of long-term restored teeth. Furthermore it was shown that bacterial invasion must be considered as a possible co-factor for the described degenerative character of the pulpal tissue.

Crowns↗
PubMed1993

Evaluation of anti-calculus efficacy. An SEM method of evaluating the effectiveness of pyrophosphate dentifrice on calculus formation.

A double-blind, cross-over study was carried out to assess the anti-calculus effectiveness of a pyrophosphate containing cleaning gel. 2 groups of 30 heavy calculus formers were followed up comparing conventional clinical scoring systems (Volpe-Manhold-Index and Marginal-Line-Calculus-Index) and micromorphologic SEM criteria of calculus formation and inhibition. The results indicated that after a 3-month period, there was a significant reduction of calculus formation compared to a placebo gel. The proposed SEM calculus index (SEMCI) objectively reflects the reduction of supragingival calculus formation.

Adult↗
PubMed1992

Factors associated with endodontic treatment failures.

Two hundred and thirty-six cases of endodontic treatment failures, none of which had advanced periodontal disease, postperforations, or root or crown fractures were analyzed clinically, radiographically, and histobacteriologically to determine the major factor(s) for treatment failures. It was found that there was a correlation between bacterial infection in the canal system and the presence of periradicular rarefaction in endodontic failures. This report provides evidence indicating that the major factors associated with endodontic failures are the persistence of bacterial infection in the canal space and/or the periradicular area and the presence of preoperative periradicular rarefaction. The apical extent of root canal fillings, i.e. underfilled, flush-filled, or overfilled, seems to have no correlation to treatment failures.

Bacterial Infections↗