Introduction: The survival of dental implants depends on osseointegration. Modifications to the implant surface are attractive for promoting the success of the implant. Abrading the surface of the implant with bioactive glass is an attractive option for improving the speed of osseointegration. Aims: To develop a bioactive glass that has the ability to enhance the surface roughness of the implant by embedding particles into the surface and to investigate the effect of grit blast parameters on the removal of the titanium from the surface. Methods: Three glasses based on SiO2-CaO-Na2O-P2O5-CaF2 were synthesized by a melt quench technique. The glasses were characterised and investigated for their bioactivity. Titanium discs were abraded with coarse glass particles by using a grit blast technique with different parameters, such as, distance, air pressure and speed. The depth, width of the abraded line and surface roughness (Ra) were measured by light profilometer. The distribution of the glasses on the titanium surface was measured by SEM-EDX. The biocompatibility of the abraded discs was tested in vitro using MC3T3-E1 cell line. Results: All glasses exhibited an amorphous structure with varied bioactivity. Changing the abrasion parameters influenced the amount of titanium removed and the surface coverage. The harder the glass the lower the amount of titanium removed and the wider the width of the abraded area. The Ra was significantly increased from 0.1μm to 1.6μm. The SEM-EDX analysis confirmed that the glasses were widely distributed and a higher coverage was seen with the harder glass. The abraded discs showed good biocompatibility in vitro. Conclusions: The designed compositions were successfully modifying the surface of the titanium. They are abrasive enough to significantly embed into the titanium surface by using the grit blast technique and increase their surface roughness. TheIntroduction: The survival of dental implants depends on osseointegration. Modifications to the implant surface are attractive for promoting the success of the implant. Abrading the surface of the implant with bioactive glass is an attractive option for improving the speed of osseointegration. Aims: To develop a bioactive glass that has the ability to enhance the surface roughness of the implant by embedding particles into the surface and to investigate the effect of grit blast parameters on the removal of the titanium from the surface. Methods: Three glasses based on SiO2-CaO-Na2O-P2O5-CaF2 were synthesized by a melt quench technique. The glasses were characterised and investigated for their bioactivity. Titanium discs were abraded with coarse glass particles by using a grit blast technique with different parameters, such as, distance, air pressure and speed. The depth, width of the abraded line and surface roughness (Ra) were measured by light profilometer. The distribution of the glasses on the titanium surface was measured by SEM-EDX. The biocompatibility of the abraded discs was tested in vitro using MC3T3-E1 cell line. Results: All glasses exhibited an amorphous structure with varied bioactivity. Changing the abrasion parameters influenced the amount of titanium removed and the surface coverage. The harder the glass the lower the amount of titanium removed and the wider the width of the abraded area. The Ra was significantly increased from 0.1μm to 1.6μm. The SEM-EDX analysis confirmed that the glasses were widely distributed and a higher coverage was seen with the harder glass. The abraded discs showed good biocompatibility in vitro. Conclusions: The designed compositions were successfully modifying the surface of the titanium. They are abrasive enough to significantly embed into the titanium surface by using the grit blast technique and increase their surface roughness. The glass abraded discs show both good bioactivity and biocompatibility in vitro.

Background: Blood clot formation is one of the first events in bone regeneration and osseointegration. The blood clot adheres to dental implants with hydrophilic surfaces more favorably than to those with hydrophobic surfaces. This appears to result in better bone healing and bone fill of defects around dental implants. Objective: To assess the impact of blood clot stabilization at modSLA titanium implants on bone formation in chronic-type defects in a dog model. Material & methods: Ten modSLA implants were installed in 5 dogs after creation of saddle-type buccal-lingual bony defects. In 5 implants (test sites), the blood clot was removed by sterile saline irrigation, while the clot was left undisturbed on the other 5 implants (control sites). After 8 weeks of healing, the animals were sacrificed and sections were prepared for histomorphometric analysis. The following measurements were performed: The residual defect length (DL), the buccal and lingual most coronal level of bone in contact with the implant (CBI-b and CPI-l), the new bone height (NBH), the percentage of bone to implant contact (BIC), the area of new bone fill (BF), the difference in buccal and lingual dimensions of CBI (D-CBI), and percentage of linear bone fill (PLF). Results: the mean values of DL were similar in both groups (3.4 mm). All parameters assessed were consistently more favorable in control sites: CBI-b: 1.3 vs. 1.5, CBI-l: 1.3 vs. 0.8, D-CBI: -0.2 vs -0.5, NBH: 1.9 mm vs. 2.1 mm, PLF: 57.1% vs. 64.5% and BF: 4.4 mm? vs. 6.0 mm?. However, these differences were not statistically significant. Conclusion: In the light of consistently more favorable parameters assessed for the healing of saddle-shaped bony defects around implants, it is assumed that a stabilized blood clot contributed to early bone regeneration and osseointegration. Undisturbed blood clot formation may, indeed, be a prerequisite for optimal treatment outcomes. However, owing to the small sample size in the present study, these tendencies ought to be explored in further studies. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

published_or_final_version / abstract / toc / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy

Made available in DSpace on 2015-01-26T13:21:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-03-14Bitstream added on 2015-01-26T13:30:19Z : No. of bitstreams: 1 000805961_20170314.pdf: 349223 bytes, checksum: 448acffc1a9c58492a9b1e664b17feac (MD5) Bitstreams deleted on 2017-03-17T12:38:10Z: 000805961_20170314.pdf,. Added 1 bitstream(s) on 2017-03-17T12:39:09Z : No. of bitstreams: 1 000805961.pdf: 4843456 bytes, checksum: f128a369968d68e92229dadbd28be7df (MD5) / O objetivo deste trabalho foi avaliar o processo de reparo ósseo e a osseointegração de implantes inseridos em leitos cirúrgicos preparados por meio de Brocas Convencionais, Ultrassom Piezoelétrico e LASER Er,Cr:YSGG. Como objetivo secundário, foi testada a habilidade do ultrassom cirúrgico de estumilar a liberação de citocinas e fatores de crescimento ósseo durante o processo de reparo. Para tanto, dois estudos distintos foram conduzidos. No Estudo 1, 144 ratos foram divididos em 3 grupos (Grupos Broca, LASER e Piezo) com 48 animais cada. Mini implantes usinados foram instalados em ambas as tíbias de cada animal em alvéolos cirúrgicos preparados pelos 3 sistemas testados de acordo com o grupo ao qual o animal pertencia Após a intervenção cirúrgica, 8 animais por grupo foram sacrificados aos 0, 3, 7, 14, 30 e 60 dias pós-operatórios.. O implante da tíbia direita foi utilizado para o ensaio de torque de remoção e o da tíbia esquerda, para análise de Contato-Osso-Implante (COI) e Fração de Área Ocupada por Osso (FAOO). No Estudo 2, 174 animais foram divididos nos mesmos grupos experimentais – Broca, Piezo e Laser – com 63, 63 e 48 animais cada, respectivamente. Defeitos ósseos de 2mm de diâmetro foram produzidos na tíbia direita dos animais usando um dos três dispositivos testados de acordo com o grupo ao qual o animal foi designado. Oito animais de cada grupo foram sacrificados aos 0, 3, 7, 14 30 e 60 dias e a cicatrização óssea foi analisada por histomorfometria e detecção imuno-histoquímica de Osteocalcina, Osteoprotegerina, Rankl, Vegf e Caspase-3. Cinco animais dos Grupos Broca e Piezo foram sacrificados aos 3, 7 e 14 dias e o espécimes coletados foram utilizados para análise de PCR quantitativo (Q-PCR). Os resultados do Estudo 1 demonstraram a osseointegração dos implantes no três grupos estudados. No Grupo Broca a formação óssea ocorreu mais precocemente, porém um aumento significativo no... / The aim of this study was to evaluate the bone healing process and osseointegration of implants placed in sockets prepared by conventional Drills, Piezosurgery and Er,Cr:YSGG laser. As a secondary objective we tested the hability of Piezosurgery of enhancing the bone repair by releasing of citokynes and growth factor. Therefore, two different studies were conducted. In study 1, 144 rats were assigned to 3 groups: Groups Drill, Laser and Piezo, with 48 animals in each group. Machined mini-implants were placed in both tibiae of each animal in sockets prepared by the three tested systems, according to the group in which it was assigned. After the surgical procedures, 8 animals were sacrificed postoperatively at 0, 3, 7, 14, 30 and 60 days in each group. The implant of the right tibia was used for removal torque test and the left tibia implant was used for Bone-to-Implant Contact (BIC) and Bone Area Fraction Occupancy (BAFO) analysis. In Study 2, 174 animals were ssigned to the same experimental Goups - Drill, Piezo and Laser – with 63, 63 and 48 animals in each group. Bone defects with 2mm in diameter were created in the righ tibia of each animal using one of the three tested devices according to the group in which it was assigned. Eight animals of each group was sacrificed at 0, 3, 7, 14 , 30 and 60 days and bone healing were analyzed by means of histomorphometry and immunohistochemical detection of Osteocalcin, Osteoprotegerin, Rankl, Vegf and Caspase-3. Also, 5 animals form Gorups Drill and Piezo were sacrificed at 3, 7 and 14 days and the bone samples were used for quantitative PCR (Q-PCR) analysis. Results of Study 1 demonstrated implant osseointegration in all experimental groups. The Group Drill presented early bone formation, however, significant increasing in torque removal values occurred only at 30 days. In Groups Laser and Piezo, removal torque increased early and bone healing around the implant was progressively increased until...

Orientador: Elcio Marcantonio Junior / Banca: Roberto Henrique Barbeiro / Banca: Wilson Roberto Poi / Banca: Thalita Pereira Queiroz / Banca: Paulo Tambasco de Oliveira / Resumo: O objetivo deste trabalho foi avaliar o processo de reparo ósseo e a osseointegração de implantes inseridos em leitos cirúrgicos preparados por meio de Brocas Convencionais, Ultrassom Piezoelétrico e LASER Er,Cr:YSGG. Como objetivo secundário, foi testada a habilidade do ultrassom cirúrgico de estumilar a liberação de citocinas e fatores de crescimento ósseo durante o processo de reparo. Para tanto, dois estudos distintos foram conduzidos. No Estudo 1, 144 ratos foram divididos em 3 grupos (Grupos Broca, LASER e Piezo) com 48 animais cada. Mini implantes usinados foram instalados em ambas as tíbias de cada animal em alvéolos cirúrgicos preparados pelos 3 sistemas testados de acordo com o grupo ao qual o animal pertencia Após a intervenção cirúrgica, 8 animais por grupo foram sacrificados aos 0, 3, 7, 14, 30 e 60 dias pós-operatórios.. O implante da tíbia direita foi utilizado para o ensaio de torque de remoção e o da tíbia esquerda, para análise de Contato-Osso-Implante (COI) e Fração de Área Ocupada por Osso (FAOO). No Estudo 2, 174 animais foram divididos nos mesmos grupos experimentais - Broca, Piezo e Laser - com 63, 63 e 48 animais cada, respectivamente. Defeitos ósseos de 2mm de diâmetro foram produzidos na tíbia direita dos animais usando um dos três dispositivos testados de acordo com o grupo ao qual o animal foi designado. Oito animais de cada grupo foram sacrificados aos 0, 3, 7, 14 30 e 60 dias e a cicatrização óssea foi analisada por histomorfometria e detecção imuno-histoquímica de Osteocalcina, Osteoprotegerina, Rankl, Vegf e Caspase-3. Cinco animais dos Grupos Broca e Piezo foram sacrificados aos 3, 7 e 14 dias e o espécimes coletados foram utilizados para análise de PCR quantitativo (Q-PCR). Os resultados do Estudo 1 demonstraram a osseointegração dos implantes no três grupos estudados. No Grupo Broca a formação óssea ocorreu mais precocemente, porém um aumento significativo no... / Abstract: The aim of this study was to evaluate the bone healing process and osseointegration of implants placed in sockets prepared by conventional Drills, Piezosurgery and Er,Cr:YSGG laser. As a secondary objective we tested the hability of Piezosurgery of enhancing the bone repair by releasing of citokynes and growth factor. Therefore, two different studies were conducted. In study 1, 144 rats were assigned to 3 groups: Groups Drill, Laser and Piezo, with 48 animals in each group. Machined mini-implants were placed in both tibiae of each animal in sockets prepared by the three tested systems, according to the group in which it was assigned. After the surgical procedures, 8 animals were sacrificed postoperatively at 0, 3, 7, 14, 30 and 60 days in each group. The implant of the right tibia was used for removal torque test and the left tibia implant was used for Bone-to-Implant Contact (BIC) and Bone Area Fraction Occupancy (BAFO) analysis. In Study 2, 174 animals were ssigned to the same experimental Goups - Drill, Piezo and Laser - with 63, 63 and 48 animals in each group. Bone defects with 2mm in diameter were created in the righ tibia of each animal using one of the three tested devices according to the group in which it was assigned. Eight animals of each group was sacrificed at 0, 3, 7, 14 , 30 and 60 days and bone healing were analyzed by means of histomorphometry and immunohistochemical detection of Osteocalcin, Osteoprotegerin, Rankl, Vegf and Caspase-3. Also, 5 animals form Gorups Drill and Piezo were sacrificed at 3, 7 and 14 days and the bone samples were used for quantitative PCR (Q-PCR) analysis. Results of Study 1 demonstrated implant osseointegration in all experimental groups. The Group Drill presented early bone formation, however, significant increasing in torque removal values occurred only at 30 days. In Groups Laser and Piezo, removal torque increased early and bone healing around the implant was progressively increased until... / Doutor

Orientador: Mari Eli Leonelli de Moraes / Co-orientador: Luana Marotta Reis de Vasconcellos / Banca: João Paulo Barros Machado / Banca: Natal Nerímio Regone / Banca: Maria Aparecida Neves Jardini / Banca: Sergio Lucio Pereira de Castro Lopes / Resumo: A Implantodontia é uma das áreas da Odontologia que mais tem evoluído nas últimas décadas. Diversos estudos são desenvolvidos na intenção de otimizar o processo de osseointegração utilizando a nanotopografia na superfície dos implantes. Atualmente o processo de anodização da superfície vem se destacando entre estas técnicas. Desta forma, o objetivo nesta pesquisa foi obter nano rugosidades e fase de anatase em implantes odontológicos de Titânio, buscando a otimização da osseointegração. Sessenta implantes foram caracterizados quanto à morfologia, por meio de microscopia de força atômica (AFM) e Microscopia Eletrônica de Varredura (MEV); quanto à composição química, por análise por detector de espectrometria por espalhamento de energia (EDS) e Espectroscopia Raman; e por fim, quanto ao potencial de corrosão, pela análise de impedância eletroquímica (EIE). A osteogênese, in vivo, foi comparada por Radiografia periapical (RP), Microtomografia Computadorizada (µTC) e teste de remoção por torque reverso; e, a análise in vitro, foi realizada por teste de citotoxicidade por MTT [(brometo de 3-4,5-dimetiltiazol-2-il)-2,5-difeniltetrazoliol]. Os implantes foram divididos em: G1 (controle); Grupo 2 (jateado); Grupo 3 (anodizadoexperimental). Cada coelho recebeu um implante de cada grupo nas tíbias direita e esquerda, e cinco coelhos, foram eutanasiados 2 e 6 semanas após a cirurgia. Os implantes da tíbia direita foram submetidos à RP e à µTC; e os da tíbia esquerda, ao teste de torque reverso e análise de citotoxicidade por MTT. AFM e MEV comprovaram a presença de nano rugosidades na superfície em G3; análises de EDS e Espectroscopia Raman, demonstraram aumento da camada do filme de TiO2 e a obtenção de anatase em G3. Na RP, nenhum implante apresentou halo radiolúcido. Na µTC, G3 foi sempre superior aos demais grupos nos parâmetros observados: BV, BV/TV, Tb.Th. No teste de torque reverso, houve... / Abstract: The Implantology is one of the areas of dentistry that has most evolved in recent decades. Many studies have been developed with the intention of optimizing the osseointegration process using nanotopography on the surface of the implants. Currently the surface of the anodizing process has stood out among these techniques. Thus, the aim of this research was to obtain nano roughness and anatase phase in dental Titanium implants, seeking for the optimization of the osseointegration. Sixty implants were characterized for morphology by atomic force microscopy (AFM) and Scanning Electron Microscopy (SEM); in chemical composition, by mass spectrometry detector energy scattering (EDS) and Raman spectroscopy; and finally, as the potential for corrosion, the electrochemical impedance analysis (EIS). Osteogenesis in vivo was compared by Periapical Radiography (PR), Computed Microtomography (μTC), removal reverse torque test; and in vitro analysis, it was performed by MTT cytotoxicity assay [(bromide 3-4,5-dimethylthiazol-2-yl) -2,5-difeniltetrazoliol]. The implants were divided into G1 (control); Group 2 (sandblasted); Group 3 (anodized-experimental). Each rabbit received an implant of each group in the right and left tibias and five rabbits were euthanized 2 and 6 weeks after surgery. The implants of the right tibia underwent PR and μTC; and the left tibia, the reverse torque test and MTT cytotoxicity assay. AFM and SEM confirmed the presence of nano roughness on the surface in G3; EDS analysis and Raman spectroscopy showed increased TiO2 film layer and obtainment of anatase G3. In PR, no implant presented radiolucent halo. In μTC, G3 has always been higher than the other groups in the observed parameters: BV, BV / TV, Tb.Th. In the reverse torque test, It was required greater removal force of anodized implants. In the MTT test, the experimental implants were nontoxic to cells. It was conclude that the anodizing process used in this study... / Doutor

The use of polymers in orthopaedics is steadily increasing. In some markets, such as spinal fusion and soft tissue anchors, the polymer polyetheretherketone (PEEK) is already the material of choice in the majority of implants. Despite PEEK’s widespread use, it is often associated with poor osseointegration, which can lead to implant loosening and ultimately failure of the device. Many attempts have been explored to improve the osseointegration of PEEK but none have had widespread clinical success. In this dissertation, a novel surface porous structure has been created, where limiting the porosity to the surface maintains adequate mechanical properties for load bearing applications while providing a surface for improved osseointegration. Careful control of the processing parameters resulted in tunable porous microstructures optimized for bone ingrowth: highly interconnected 200-500µm pores with porosity ranging from 60-85% and pore layers from 300-6000µm thick. Mechanical characterization, including monotonic tensile and compression, tensile fatigue, shear, and abrasion tests, were used to probe the effects of the surface porosity on the relevant mechanical properties of the material. In addition, the effect of surface porosity and surface roughness on the mechanical properties of a range of thermoplastics with varying chemistries and crystallinities was explored. This research showed that there is a great disparity in the notch sensitivity of polymers that correlates to the polymers fracture toughness as well as trends in the monotonic stress-strain curve. The results illustrate that care must be taken in the design of polymeric implants, especially when introducing topographical changes to promote osseointegration, in order to ensure they maintain adequate load-bearing capacity. Finally, preliminary in vitro and in vivo data demonstrated the ability of surface porous PEEK (PEEK-SP) to promote osseointegration. Cells grown on PEEK-SP demonstrated enhanced mineralization and differentiation, suggesting the ability of PEEK-SP to facilitate bone ingrowth. The potential of PEEK-SP was further demonstrated by implantation in a rat femoral segmental defect model which demonstrated bone ingrowth and reduced formation of a fibrous capsule.

University of Macau / Institute of Chinese Medical Sciences

Zahnverluste können zu erheblichen Beeinträchtigungen der Phonetik, Ästhetik und Funktionalität führen. Daher muss Zahnersatz das natürliche Gebiss funktionell ersetzen, möglichst ohne als künstlich empfunden zu werden. Die dentale Implantologie als moderne Therapieform zur Behandlung verloren gegangener Zähne, weist heutzutage hohe Erfolgsraten auf. Dennoch ist die Suche nach Misserfolgsursachen unerlässlich, um auch langfristig eine Therapiesicherheit bieten zu können. Die vorliegende Untersuchung hatte das Ziel, den Einfluss von Erkrankungen wie Diabetes mellitus, Nikotinabusus und kardiovaskulären Erkrankungen auf die Implantattherapie und deren Erfolg zu untersuchen. 1904 Patienten, welche in einem Zeitraum von 15 Jahren (9.6.1995 - 16.7.2010) in der Zahnarztpraxis Dr. med. Robert Böttcher mit Implantaten verschiedener Implantatsysteme versorgt wurden, wurden in dieser Studie untersucht. Das Patientengut bestand aus 1107 (58,1%) Frauen und 797 (41,9%) Männern. Im Mittel wurden pro Patient 3 Implantate gesetzt. Das mittlere Alter der 1904 Patienten bei Implantation lag bei 52 Jahren (Minimum: 15 Jahre, Maximum: 86 Jahre). 58% der Implantate (n=3608) wurden bei Frauen eingesetzt. 42% der Implantate (n=2609) wurden bei Männern inseriert. Bei der Analyse implantatabhängiger Faktoren stellte sich der Parameter „Indikation“ und auch die Interaktion des Parameters Indikation „2b“ und der Einheildauer als signifikant dar. Erstaunlicherweise haben Implantate, welche in „Schaltlücken“ inseriert wurden, ein zunächst über 65000-fach höheres Risiko explantiert zu werden. Dieses Risiko nimmt allerdings mit zunehmender Einheildauer signifikant ab. So ist es nach einem Monat nur noch 1478-fach erhöht, nach 2 Monaten nur noch 33-fach erhöht. Ein Erklärungsansatz für das bessere Überleben der Implantate im zahnlosen Unterkiefer liegt in der dort zu findenden Knochenqualität mit einem deutlich höheren Anteil an Knochenkompakta und der daraus resultierenden erhöhten Widerstandsfähigkeit. Die Indikation „Schaltlücke“ wurde in der vorliegenden Untersuchung zudem vor allem im Seitenzahnbereich versorgt. Hier kommt es zu einer höheren Kaubelastung und anatomisch bedingt ist in der Seitenzahnregion mit einer geringeren Restknochenhöhe zu rechnen. Zudem kommt es durch den frühen Verlust der Molaren (6-Jahres-Molar) zu einer vertikalen und horizontalen Knochenatrophie, was wiederum bei der Implantation in dieser Position Augmentationsmaßnahmen erfordern kann. Diese sind erwartungsgemäß mit einem höheren Verlustrisiko assoziiert. Weiterhin kann durch Mangel an fixierter Gingiva eine Optimierung der Weichgewebssituation in Form einer Vestibulumplastik erforderlich sein. Dies kann mit einem erhöhten Risiko einer Periimplantitis und schließlich einem Implantatverlust einhergehen. In der Literatur fanden sich ähnliche Ergebnisse bei Shatkin et al. (2007). Hier kam es zu den höchsten Verlusten in der posterioren Maxillaregion. Auch Machtei et al. (2007) und Johns et al. (1992) ermittelten die höchste Verlustrate im Bereich der oberen ersten Molaren. [81, 102] Auch die Einheildauer und die Interaktion der Einheildauer mit der Zeit erwiesen sich in der vorliegenden Arbeit als signifikante Variablen. Es erstaunt jedoch nicht, dass sich das Risiko eines Implantatverlustes mit zunehmender Einheildauer, in dieser Studie um den Faktor 3,89 pro Monat Einheildauer, reduziert. Gerade bei zusätzlichen Maßnahmen wie Osteoplastiken oder der gesteuerten Geweberegeneration werden die Einheilzeiten auf bis zu zwölf Monate verlängert um eine optimale Osseointegration zu gewährleisten. Ein offen-transgingivaler Einheilmodus zeigte gegenüber dem gedeckt-subgingivalen Einheilmodus mit etwa 3% Verlust nach 10 Jahren ein signifikant schlechteres Überleben. Additive Implantatoberflächen zeigten im Vergleich zu subtraktiven Oberflächen signifikant bessere 10-Jahresüberlebensraten. Die Verlustraten lagen bei letztgenannten bei bis zu 5% nach 10 Jahren. Erwartungsgemäß wurden in dieser Studie Augmentationsmaßnahmen und zunehmende Implantatanzahl als Risikofaktor einer Explantation identifiziert. So haben augmentierte Implantate ein 2,4-fach höheres Risiko explantiert zu werden. Das relative Risiko eines Implantatverlustes nimmt mit zunehmender Implantatanzahl um den Faktor 1,18 zu. Implantatregion, -durchmesser und -länge, wie auch der Implantationszeitpunkt und die Knochenqualität konnten nicht als Risikoparameter identifiziert werden. Bei der Untersuchung patientenabhängiger Faktoren erwies sich das Patientenalter als signifikanter Einflussfaktor auf den Implantaterfolg. So kam es bei Patienten im höheren Lebensalter seltener zu Implantatverlusten. Pro Lebensjahr sank das Risiko eines Implantatverlustes um den Faktor 0,9. Dies lässt sich durch ein größeres Gesundheitsbewusstsein im zunehmenden Lebensalter erklären. Zudem bestand bei jungen Patienten in dieser Untersuchung ganz überwiegend eine Indikation zur Einzelzahnversorgung beispielsweise bei Nichtanlagen der oberen seitlichen Schneidezähne, multiplen Nichtanlagen oder nach Unfällen (Fahrrad, Skater, Schlitten). Diese Indikationen erfordern häufig Augmentationsmaßnahmen, teilweise auch Knochenblocktransplantationen, was insgesamt wiederum zu einem erhöhten Implantatverlustrisiko führt. Das Patientengeschlecht hatte keinen Einfluss auf den Implantaterfolg. Wie erwartet, konnte im untersuchten Patientengut ein negativer Einfluss des Rauchens auf den Implantaterfolg aufgezeigt werden. In der Literatur wird dem Nikotinabusus nahezu einheitlich ein negativer Einfluss auf das Implantatüberleben zugeschrieben. Eine diabetische Stoffwechsellage hatte in unserem Patientenkollektiv keinen nachweisbaren Einfluss auf den Implantaterfolg. Hingegen wurde bei Patienten mit kardiovaskulären Erkrankungen nach 10 Jahren eine signifikant geringere Implantatüberlebenswahrscheinlichkeit nachgewiesen. Die Hypothese der Arbeit, dass Risikofaktoren zu Komplikationen bei der dentalen Implantation führen und somit das Implantatüberleben beeinflussen, konnte in dieser Untersuchung bestätigt werden. Insgesamt ist in Anbetracht des Patienten-individuellen Risikos eine spezifische Risiko-Nutzen-Abwägung erforderlich, da eine implantatprothetische Versorgung der Patienten mit definierten Risikofaktoren nicht generell kontraindiziert ist. / Missing teeth can result in substantial impairments in oral functions and phonetics and are also aesthetically unsatisfactory. Therefore, artificial teeth should replace the functions of natural teeth and ideally should not be perceived as artificial. Oral implantology is a modern therapy for missing teeth that now has a high rate of success. Nevertheless, understanding the causes of failure of oral implants is essential in order to provide patients with good, long-term results. The goal of this investigation was to examine the influence of diabetes mellitus, nicotine abuse, and cardiovascular disease on implant therapy and its success. The patients in this study were given implants from different systems over a period of 15 years (June 9, 1995 – July 16, 2010) in the dental practice of Dr. med. Robert Böttcher. A total of 1904 patients were used in the analysis; 1107 (58.1%) of these were women and 797 (41.9%) were men. On average, there were 3 implants per patient. The mean age of the patients was 52 years (minimum: 15 years, maximum: 86 years). The analysis of implant-dependent factors found the parameter indication “2b” and also the interaction of the parameter indication „2b“ and the healing period to be significant. Surprisingly, implants that were inserted in „interdental gaps“ had a 65,000 times higher risk of explantation compared to implants in an edentulous jaw. This risk decreased significantly however with increased healing time. Specifically, the risk is increased only 1478 times after one month and only 33 times after 2 months. An explanation for the better success of implants in the edentulous jaw may be the better bone quality and the resulting increased ruggedness that can be found there. For this study, implants with the indication „interdental gap“ were used in the area of the lateral teeth. Here there is a higher chewing load and anatomically this region a lower bone height can be expected. Furthermore, the early loss of the molar teeth (6-Year-Molar) leads to more vertical and horizontal bone resorption. This bone loss results in the need for augmentation procedures when implantation is planned in these regions. As expected, this is associated with a higher rate of loss. Also, the lack of attached gingiva may make vestibulumplasty necessary in order to optimize the soft tissue situation. This correlates with an increased risk of a periimplantitis and implant loss. A retrospective analysis by Shatkin et al. (2007) reported similar findings, with the highest losses occurring in the posterior maxilla. Machtei et al. (2007) and Johns et al. (1992) found the highest loss rate with the upper first molar teeth. [81, 102] The healing time and the interaction of the healing period with the time proved to be significant variables. It is not unexpected that the risk of implant failure is reduced over the duration of healing time, which in this study was found to be reduced by a factor of 3.89 per month. In particular, when additional measures such as the guided tissue regeneration or osteoplasties are needed, the healing period could be extended up to twelve months to ensure an optimal osseointegration. The non-submerged healing exhibited an approximately 3% significantly worse survival rate after 10 years compared with the submerged healing. Additive implant surfaces showed significantly better 10-year-survival rates compared with subtractive implant surfaces. The latter had loss rates of up to 5% after 10 years. As expected, in this study augmentation procedures and increasing number of implants were identified as risk factors for implant failure. Implants in augmentes bone had a 2.4 times higher risk of an explantation. The relative risk of an implant failure increased with an increasing number of implants by a factor of 1.18. The region of implantation, implant diameter and length, the time of implant placement, and the bone quality could not be identified as risk factors. Analysis of patient-dependent factors found that patient age had a significant influence on implant success. Consequently, it became more rare to use implants in elderly patients. The risk of an implant failure decreased with each year by a factor of 0,9 . On the one hand this can be explained by an increasing health consciousness in elderly people. Furthermore, in young patients the indication for single tooth restoration was given more often, for example in cases of agenesis of teeth or in the context of accidents (bicycle, skater, sleigh). This indication which frequently require augmentation procedures, including bone block transplantions, also could have increased implant failure. The patient sex did not have an influence on implant success. As expected, smoking had a negative influence on implant success in the examined patient population. In the literature, a negative influence on implant survival is almost uniformly found with nicotine abuse. A diagnosis of diabetes did not have a demonstrable influence on implant success in our patients. However, patients with cardiovascular diseases were found to have a significantly lower probability of implant survival after 10 years. The working hypothesis that risk factors lead to complications in oral implantology and thus affect implant survival was supported by this investigation. In conclusion, our results suggest that an individual risk-benefit analysis is required, as implant-supported prosthetic restoration in patients with defined risk factors is not generally contraindicated.

Objectives: The present work was under taken to compare osseointegration of immediately and delayed restored implants in a sheep model, and to compare methods of assessing osseointegration. Methods: Twenty wide-platform implants were placed in the posterior mandibles of 10 sheep, 3 months after premolar extractions. Ten were control implants placed and restored after 3 months of submerged healing. Ten were test implants placed contralaterally and immediately restored. Animals were sacrificed after a further 3 months of healing. At each experimental stage implant stability was measured with resonance frequency analysis (RFA) and standardized radiographs were taken. Tissue blocks with the implants were embedded in acrylic resin. The specimens were analysed by three-dimensional micro tomogram (micro-CT) images. Ground sections of the tissue blocks were then prepared for light microscopy and quantitative morphometry. Morphometric parameters computed by both methods were mean percent bone-to-implant contact (BIC) and mean percent bone density (BD). Radiographic, stability and morphometric measurements were compared statistically. Results: The survival rate was 60% (controls) versus 40% (test) (p=0.28). Mean crestal bone levels after three months restoration did not differ significantly between control (5.54 � 0.92) and test groups (4.35 � 1.61) (p=0.56). All surviving implants were stable at stage three and RFA values in implant stability quotient (ISQ) did not differ significantly between the two groups (test 82.3 � 3.9 versus control 78.8 � 4.3, p=0.36). No correlation was found between crestal bone loss and RFA (Spearman�s rho =-0.27, p=0.46). Histomorphometric analysis found no statistical difference (%BIC test 65.65 � 12.7%, control 53.36 � 6.41%, p=0.18; and %BD test 54.84 � 8.45%, control 64.69 � 13.57%, p=0.11). A similar trend was observed for mean micro-CT (%BIC test 65.72 � 72, control 50.84 � 4.19, p=0.11). Histology revealed high density inflammatory infiltrates beneath the sulcular and pocket epithelium. No significant difference was found between histomorphometric (HMA) and microCT analysis (%BIC p=0.08, %BD p=0.08). A statistically significant correlation was observed between HMA and microCT for %BIC (Spearman�s rho = 0.89, p=0.02) but not %BD (Spearman�s rho = 0.51, p=0.30). Conclusions: The results suggest that the sheep mandibular model has limited potential for evaluation of implants designed for poor quality bone and for the assessment of implant loading protocols. This thesis does highlight the potential for the use of this model in peri-implantitis studies. The results suggest that morphometric variables determined by HMA and microCT analysis are comparable, however further studies are required to standardize the microCT protocol to reduce metal artifacts and enhance bone-implant contrast.