Effects of microabrasion on substance loss, surface roughness, and colorimetric changes on enamel in vitro.

OBJECTIVES: To determine in vitro the effects of 2 commercially available microabrasion compounds (Prema [Premiere Dental Products] and Opalustre [Ultradent]) on human enamel under standardized conditions after treatment periods of 10, 20, 30, and 40 seconds. Nonacidified pumice served as an abrasive control compound. METHOD AND MATERIALS: Mean substance loss was determined by measuring dissolved Ca2+ using atomic absorption spectrophotometry. Differences in the mean surface roughness were profilometrically assessed. These findings were completed with micromorphologic observations using SEM. In addition, color changes after microabrasion were evaluated using the CIE L*a*b* system. RESULTS: Opalustre caused the highest tooth substance loss, followed by the Prema compound and pumice, which showed a lesser substance-removal capacity. These findings were in concordance with the mean surface roughness difference measurements and micromorphologic analyses. Microabrasion did not cause any significant colorimetric changes. CONCLUSION: Microabrasion should be considered a microinvasive method, and clinical application should be used with caution to avoid excessive substance removal. Subsequent polishing appears crucial to maintain optimal esthetics and avoid surface alterations.

[In vitro tests of internal tooth whitening agents on colored solutions do not replace tests on teeth]. / In-vitro-Prüfung interner Zahnbleichmittel an Farblösungen ersetzt Tests an Zähnen nicht.

Two in vitro tests for the assessment of whitening agents were evaluated. A simple, reproducible and cost-effective model using coloured solutions was compared to a tooth model. The following bleaching agents were investigated: 1) Sodium perborate tetrahydrate/30% H2O2, 2) sodium perborate tetrahydrate/3% H2O2, 3) thermocatalytic procedure with 30% H2O2 and 4) Opal-escence Endo. In the model using coloured solutions, the light absorption of the solutions was assessed one and 24 hours after application of the whitening agents. In discoloured teeth, whitening agents were placed in a simulated access cavity. In groups 1, 2, and 4, the agents were left in the cavity for three days, whereas in group 3 the substance was applied three times for 30 seconds. Bleaching processes were repeated three times. All bleaching agents proved effective in the model with coloured solutions, as well as in the tooth model. The effect was most pronounced after the first bleaching step. The results showed, however, that the simplified experiment with coloured solutions cannot replace the tooth model.

Biocompatibility of Beta-tricalcium phosphate root replicas in porcine tooth extraction sockets - a correlative histological, ultrastructural, and x-ray microanalytical pilot study.

This investigation studies porcine tissue response in tooth extraction sockets treated with root replicas made out of Beta-tricalcium phosphate (Beta-TCP; Beta-Ca(3)(PO(4))(2)) granules, molded and held together by thermal fusion of a thin film of polyglycolic-polylactic acid copolymer. Six left mandibular third incisors (n (1)/4 6) of experimental pigs are treated with the root replicas and four contralateral incisors are used as nontreated controls (n (1)/4 4). Two animals each were killed at 20, 40, and 60 weeks of observation periods. The mandibular jaw segments were prepared in toto for light microscopy by resin embedding and serial ground sectioning. Additionally, one Beta-TCP-treated socket at 60 weeks was thoroughly investigated by correlative light, electron microscopic and electron probe X-ray microanalysis to assess the bio-absorbability and host removal of the replica material from the implant site. The extraction wounds of the animals healed satisfactorily with very little histologically observable differences in the healing pattern of the test and control sites. The Beta-TCP was completely removed from extracellular sites, but at 60 weeks, remnants of it were found in the cytoplasm of multinucleated giant cells. The root replicas made out of Beta-TCP were biocompatible and bioabsorbable. Osseous healing occurred both in the test and control sockets, but the healing process was delayed due to the presence of Beta-TCP particles.

[Prevention of alveolar ridge resorption after tooth extraction--a review]. / Alveolarkammprävention nach Zahnextraktion--eine Literaturübersicht.

Alveolar bone resorption is frequently observed after tooth extraction. Atrophy of the alveolar ridge may cause esthetic and surgical problems in prosthetic dentistry. Augmentative measures may thus be required to guarantee optimal prosthetic replacement of the lost tissues. Augmentative bone treatment may result in extensive surgical interventions and increased treatment costs. Alveolar ridge prophylaxis immediately upon tooth extraction may reduce such sequelae for both, the treating dentist and the patient. Attempts to reduce alveolar bone resorption have included the placement of natural roots, root analogues, and immediate implants into the extraction socket, sometimes in combination with membrane or graft techniques. In the current review of the literature, techniques for alveolar ridge preservation are discussed.

Observations on healing of human tooth extraction sockets implanted with bioabsorbable polylactic-polyglycolic acids (PLGA) copolymer root replicas: a clinical, radiographic, and histologic follow-up report of 8 cases.

OBJECTIVE: The objective was to conduct a clinical, radiographic, and histologic follow-up of alveolar socket healing in 8 human cases in which the extraction sockets of the involved teeth were treated with biodegradable root replicas before metallic implants were placed. STUDY DESIGN: Chair side prepared solid and porous forms of root replicas made out of polylactic-polyglycolic acids (PLGA) copolymer were utilized. Five patients were treated with the solid form and 3 with the porous form of the replicas. The cases were followed up at regular intervals postoperatively, and standardized photographs and radiographs were taken. The cylindrical core of biopsies that were removed with trephine for placement of titanium implants were processed and examined by light and transmission-electron microscopy. RESULTS: Both forms of the root replicas were well tolerated and biodegraded by the body. There were no histologically observable pathological tissue reactions at the time of implant application. However, the solid form seemed to cause an initial decalcification of the bone surrounding the extraction sockets that was subsequently repaired along with the bone healing of the extraction sockets. Such initial decalcification of the alveolar process was not observed in the cases that were treated with the porous form of root replicas. There was wide variation in the osseous component of the trephine-harvested biopsies in both treatment groups that suggests inconsistency in bone healing of the alveolar sockets. CONCLUSION: The 2 forms of root replicas under investigation were found to be biocompatible and biodegradable. But the compact solid form may cause an initial temporary lactic acid induced decalcification of the alveolar process, which makes it unsuitable for regular clinical application as compared to the granular porous form. The observed inconsistent and unpredictable bone regeneration calls for further research to develop more optimal replica materials.

Histological, morphological, profilometric and optical changes of human tooth enamel after microabrasion.

PURPOSE: To determine the loss of enamel after a single 20-secondsapplication of a microabrasion slurry and to evaluate structural changes by means of laser fluorescence, and microscopic and optical measurements. METHODS: Defined buccal areas with a diameter of 2 mm from 16 extracted human molars were demineralized for 12 weeks using a demineralization gel (pH 4.8). The created artificial white-spot lesions were divided corono-apically in control and test sites, using a rubber cement that prospectively covered the untreated control site. Teeth were divided into two groups of eight teeth each. One group was treated with an abrasive cleaning paste (Pell-ex) and the other group with a commercially available microabrasion slurry (Opalustre) for 20 seconds, applying a load of 200 g. Before and after treatment, standardized photographs were taken for the determination of luminescence and profilometric tracings of the surface, and these were recorded for the determination of enamel loss. The grade of demineralization was quantified using a laser fluorescence method (Diagnodent). Statistical differences were checked using a Mann Whitney and student t-test. Replicas of the treated areas were made for scanning electron microscopy (SEM) analysis, and teeth were histologically investigated by polarized light microscopy. RESULTS: Loss of tooth substance was significantly higher (P < or = 0.001) for the microabrasion group (134.8 +/- 35.5 microm) compared with the abrasive cleaning paste group (4.5 +/- 1.2 microm). After treatment, statistically significant differences in fluorescence and luminescence measurements could only be detected for microabraded teeth. No significant changes were noted for teeth treated with an abrasive cleaning paste. Histological findings confirmed removal of the demineralized surface zone when microabrading the enamel, whereas no changes were observed in the test group treated with an abrasive cleaning paste. Polarized light microscopy did not indicate any changes in the mineralization pattern, for example compaction, in the treated subsurface zone.