André Büchter

Biological and biomechanical evaluation of interface reaction at conical screw-type implants

BackgroundInitial stability of the implant is, in effect, one of the fundamental criteria for obtaining long-term osseointegration. Achieving implant stability depends on the implant-bone relation, the surgical technique and on the microscopic and macroscopic morphology of the implant used. A newly designed parabolic screw-type dental implant system was tested in vivo for early stages of interface reaction at the implant surface.MethodsA total of 40 implants were placed into the cranial and caudal part of the tibia in eight male Göttinger minipigs. Resonance frequency measurements (RFM) were made on each implant at the time of fixture placement, 7 days and 28 days thereafter in all animals. Block biopsies were harvested 7 and 28 days (four animals each) following surgery. Biomechanical testing, removable torque tests (RTV), resonance frequency analysis; histological and histomorphometric analysis as well as ultrastructural investigations (scanning electron microscopy (SEM)) were performed.ResultsImplant stability in respect to the measured RTV and RFM-levels were found to be high after 7 days of implants osseointegration and remained at this level during the experimented course. Additionally, RFM level demonstrated no alteration towards baseline levels during the osseointegration. No significant increase or decrease in the mean RFM (6029 Hz; 6256 Hz and 5885 Hz after 0-, 7- and 28 days) were observed. The removal torque values show after 7 and 28 days no significant difference. SEM analysis demonstrated a direct bone to implant contact over the whole implant surface. The bone-to-implant contact ratio increased from 35.8 ± 7.2% to 46.3 ± 17.7% over time (p = 0,146).ConclusionThe results of this study indicate primary stability of implants which osseointegrated with an intimate bone contact over the whole length of the implant.

Vascular basis of mucosal color

BackgroundBesides the color of the teeth the color of the alveolar gingiva plays a crucial role in esthetic rehabilitation in dento-alveolar treatment. Whereas nowadays the color of the teeth can be determined exactly and individually, the specific influence of the red color of the gingiva on treatment has not been assessed yet. The aim of this study was to evaluate the vascularization as the basis for gingival esthetics.MethodsStandardized photographs of defined areas of the alveolar gingiva in operated and non-operated patients were taken and assigned to groups with same characteristics after color comparisons. In addition, histologic and immunohistologic analyses of gingival specimens were performed for qualitative and quantitative assessment of vessels and vascularization. Finally, colors and number of vessels were correlated.ResultsOur results demonstrated three different constellations of colors of the alveolar gingiva in healthy patients. The operated patients could not be grouped because of disparate depiction. There was a clear correlation between color and vessel number in the alveolar gingiva.ConclusionOur investigations revealed the connections between vascularization and gingival color. Recommendations for specific change or even selection of colors based on the results cannot be given, but the importance of vascularly based incision lines was demonstrated.

Strain driven fast osseointegration of implants

BackgroundAlthough the bones capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and maintenance of peri-implant bone under functional load have not been identified. Here we show that under immediate loading of specially designed dental implants with masticatory loads, osseointegration is rapidly achieved.MethodsWe examined the bone reaction around non- and immediately loaded dental implants inserted in the mandible of mature minipigs during the presently assumed time for osseointegration. We used threaded conical titanium implants containing a titanium2+ oxide surface, allowing direct bone contact after insertion. The external geometry was designed according to finite element analysis: the calculation showed that physiological amplitudes of strain (500–3,000 ustrain) generated through mastication were homogenously distributed in peri-implant bone. The strain-energy density (SED) rate under assessment of a 1 Hz loading cycle was 150 Jm-3 s-1, peak dislocations were lower then nm.ResultsBone was in direct contact to the implant surface (bone/implant contact rate 90%) from day one of implant insertion, as quantified by undecalcified histological sections. This effect was substantiated by ultrastructural analysis of intimate osteoblast attachment and mature collagen mineralisation at the titanium surface. We detected no loss in the intimate bone/implant bond during the experimental period of either control or experimental animals, indicating that immediate load had no adverse effect on bone structure in peri-implant bone.ConclusionIn terms of clinical relevance, the load related bone reaction at the implant interface may in combination with substrate effects be responsible for an immediate osseointegration state.

Primäre Implantatstabilität bei unterschiedlichen Knochenaufbereitungstechniken

Das Behandlungskonzept der Osseointegration basiert darauf, Implantate im knöchernen Lager stabil zu verankern und diese Stabilität während der funktionellen Belastung langfristig aufrechtzuerhalten. Die chirurgische Aufbereitungstechnik strebt dabei an, eine biomechanisch stabile Implantatverankerung zu erreichen. Ziel dieser Studie war es, die primäre Implantatstabilität nach unterschiedlicher Vorbehandlung des Knochenlagers in Abhängigkeit von der Implantatlänge in vitro zu evaluieren. Dazu wurden insgesamt dreißig Schraubenimplantate (Durchmesser 4,1 mm, Länge: 14, 12, 10, 8 mm, SLA-ITI®) in frisch explantierte Unterkiefer von fünf Minischweinen inseriert. Die Vorbereitung des Implantatlagers erfolgte durch Bohren (Gruppe A), Bohren und Gewindeschneiden (Gruppe B) sowie Bone Condensing (Gruppe C). Evaluiert wurde die Implantatfestigkeit durch Ausdrehversuche und Resonanzfrequenzanalyse. Die Primärstabilität wies eine deutliche Abhängigkeit sowohl von der chirurgischen Vorbehandlung als auch von der Implantatlänge auf. Die größte Stabilität im Sinne des maximalen Ausdrehmomentes ergab sich für die Implantate, die ohne weitere Vorbehandlung inseriert wurden. Zwischen der Gruppe A (507±57 Nmm) und der Gruppe C (240±31 Nmm) war beim maximalen Ausdrehmoment ein signifikanter Unterschied von p<0,05 und zwischen Gruppe B und C ein signifikanter Unterschied von p<0,05 festzustellen, während sich zwischen Gruppe A und B (466±45 Nmm, p=0,39) kein signifikanter Unterschied zeigte. Der Mittelwert der Resonanzfrequenzanalyse (RFA-Wert) bei den gebohrten Implantatlagern betrug 6000±469 Hz, bei den Implantatlagern mit zusätzlichem Gewindeschnitt 5700±557 Hz und bei den kondensierten Implantatlagern 5540±527 Hz. Die höchste Primärstabilität mit enossalen Implantaten lässt sich durch einfaches Bohren des Implantatlagers erzielen; der zusätzliche Gewindeschneider reduziert die Primärstabilität. Die Anwendung von Bone Condensern verringert die Primärstabilität signifikant. The treatment concept of osseointegration is based on a stable embodiment of implants in bone and the maintenance of stability during functional load. A goal of the surgical preparation technique is therefore to obtain a stable and firm implant anchorage. The aim of this study was to evaluate implant stability after different surgical treatment of the bony implantation bed. Thirty cylindrical solid-screw-shaped implants with standard SLA ITI configuration were implanted into the explanted mandibles of five minipigs. The implant sites were prepared either by a conventional burr technique (group A), by burr technique with additional thread cutting (group B), or by the osteotome technique (group C). Primary implant stability was evaluated by resonance frequency analysis and removal torque test. The average value of the resonance frequency analysis (RFA) was 6000±469 cycles/s in group A, 5700±557 cycles/s in group B, and 5540±527 cycles/s in group C. Removal torque values of group A (507±57 Nmm) were significantly higher than those of group B (466±45 Nmm) and group C (240±31 Nmm) (between group A and C p<0.05, group A to B p=0.39, and B to C p<0.05). It can be concluded from this study that the conventional burr technique achieves a statistically significantly better primary bone anchorage than the osteotome technique.

Malignant fibrous histiocytoma of the face: report of a case.

BackgroundSoft tissue sarcomas in the head and neck region are rare and often present a difficult differential diagnosis. The aim of our presentation is to point out the complexity of the diagnosis, treatment and follow up.Case presentationAn eighty-seven year old female patient was referred to our unit with a fast growing brownish lump on the face. Four months beforehand, a benign fibrous histiocytoma (BFH) had been removed from the same location by excision biopsy with wide tumour-free resection margins. Excision biopsy of the recurrent lesion revealed a malignant fibrous histiocytoma (MFH). Radical tumour resection was completed by extended parotidectomy and neck dissection; the skin defect was covered by a regional bi-lobed flap. No adjuvant radio- or chemotherapy was administered. Full functional and cosmetic recovery was achieved; follow-up has been uneventful more than two years postoperatively.DiscussionMalignant transformation of BFH is extremely rare and if so, extended radical surgery may give a fair chance for a favourable outcome even in patients with advanced age.

Odontogene Foci—mögliche Ursache einer Urtikaria?

Studien haben gezeigt, dass chronische odontogene Infektionen ein Risiko für myokardiale Infarkte, zerebrale Ischämien und Arteriosklerose darstellen können. Der Zusammenhang zwischen Urtikaria und dentalen Infektionen wurde jedoch bislang kaum untersucht. Da chronische dentale Infektionen häufig auftretende und ebenso leicht therapierbare Faktoren darstellen, könnte ihre Identifikation als Risikofaktoren für die weit verbreitete Urtikaria eine wichtige Rolle im Bereich der Präventivmedizin spielen. Daher führten wir eine Fall-Kontroll-Studie unter Anwendung eines standardisierten Erhebungsbogens und Untersuchungsprotokolls durch. Es wurden 66 dermatologische stationäre Patienten mit einer akuten oder chronischen Urtikaria sowie 65 gesunde, alters- und geschlechtsentsprechende Probanden als Kontrollgruppe untersucht. Der Zahnstatus wurde durch einen sog. Total Dental Index (TDI) erfasst, welcher in erster Linie Karies, Parodontitis, periapikale Läsionen, devitale und fehlende Zähne berücksichtigt. Die Auswertung der Untersuchungen zeigte einen Trend zu einem besseren dentalen Status (TDI) bei den Urtikariapatienten (n=66; 2,6 Mittelwert±1,98 Standardabweichung) im Vergleich zur Kontrollgruppe (n=65, TDI=3,3±1,86). Zusätzlich erhielten alle Patienten nach dem stationären Aufenthalt in der Hautklinik einen Fragebogen, mit welchem der Krankheitsverlauf, die Intensität und Lokalisation der Urtikaria erfasst wurden. Abschließend wurde kontrolliert, ob sich die Urtikaria nach dem stationären Aufenthalt oder nach empfohlenen und erfolgten Zahnbehandlungen zurückgebildet hatte. Statistisch kann kein signifikanter Zusammenhang zwischen Zahngesundheit (odontogenen Infektionen) und dem Auftreten von Urtikaria festgestellt werden. Recent studies have shown that chronic odontogenic infections could pose a risk for myocardial infarction, cerebral ischemia, and arteriosclerosis. However, the correlation between urticaria and dental infections has rarely been examined so far. Therefore, we performed a case-control study using a standardized questionnaire and examination. We investigated 66 patients suffering from an acute or chronic urticaria and 65 age- and sex-matched healthy patients as a control group. Dental status was determined by a so-called total dental index (TDI) which primarily reflects caries, periodontitis, periapical lesions, and nonvital and missing teeth. All 66 patients were referred from the department of dermatology. After their treatment in hospital, all patients received a questionnaire with questions on intensity and localization of the urticaria. The TDI of the urticaria patients was slightly better (n=66; 2.6±1.98) than that of the control group (n=65, TDI=3.3±1.86). Subsequently, it was determined if the urticaria had receded after dental treatment. In conclusion, chronic dental infections do not seem to correlate with an increased risk for urticaria.

Multicenter Randomized Clinical Trial: Early Loading of Implants in Maxillary Bone

PURPOSE The aim of this study was to show prognostic equivalence between implant loading in the maxilla after 12 weeks versus 4 weeks. MATERIALS AND METHODS One hundred four patients, from four centers in this open-labeled randomized multicenter prospective controlled clinical trial, were assigned to either 12 weeks or 4 weeks of unloaded healing. Two hundred sixty-nine implants (sand blasted large-grid, acid etched [SLA] surface, ≥ 4.1 mm diameter; ≥ 10 mm length) were inserted and evaluated during an individual 5-year follow-up. Primary outcome was implant success after 12 months; prognostic equivalence was characterized by a maximum difference of ± 5% in implant failure rates. RESULTS Implant-wise 1-year failure rates were estimated 3.1% (5/163 implants) in the 4 weeks group versus 3.6% (4/112 implants) in the 12 weeks group (95% confidence interval [CI] for the difference -3.2 -+4.2%); implant-wise evaluation demonstrated statistically significant prognostic equivalence of 4 and 12 weeks loading. Patient-wise 1-year failure rates were estimated 6.7% (n = 4 patients) in the 4 weeks group versus 5.1% (n = 2 patients) in the 12 weeks group (95% CI for the difference -9.6 -+6.5%). All implant failures occurred within the first 3 months of the individual observation period. Prior bone augmentation, underdimensioned drilling, bone quality, implant type, implant length, implant diameter, residual teeth, and fixing of the restoration did not reveal associations with the implant outcome: trial site, posterior jaw region, and splinting were associated with a higher failure rate. Resonance frequency analysis did not serve as a predictor of implant failures at the time of implant insertion. CONCLUSION Loading of standard SLA implants in the maxilla 4 weeks versus 12 weeks after insertion resulted in statistically equivalent failure patterns within a 1-year follow-up period; nevertheless, the observed patient-wise failure patterns of the interim analysis requires further understanding of patient-individual aspects of the early loading concept.

Aggressive Fibromatose im Kiefer-Gesichts-Bereich mit ossärer Beteiligung

BACKGROUND Aggressive fibromatosis (AF) involving bones of the head is rare and surgery is often complicated by a high recurrence rate. Interdisciplinary treatment is of the utmost importance to avoid extensive, mutilating resection. Two cases emphasize the difficulties in the management. CASE REPORTS A 67-year-old woman was referred to our unit with a blepharochalasis of the left upper palpebra and a palsy of the face on the left side. Her medical history included 12 operations over the previous 4 years for an extensive AF. MATERIAL AND METHODS Our review includes all case reports of AF involving bones of the head published between 1960 and 2004. Additionally, our two cases are presented. Signs, symptoms and outcome were analyzed in relation to different treatment options. CONCLUSION According to the literature, surgery is the most common treatment for AF in the head and neck region. Alternative modes of therapy must be considered because of the high recurrence rate and to avoid mutilating operations.