PURPOSE: The purpose of this study was to analyze anatomical spatial limitations of the existing bone for maxillary anterior implant placement in normal subjects. MATERIALS AND METHODS: Fifty Two (52) Cone Beam Computed Tomography (CBCT) scans were selected. A 3i Osteotite (6 x 15mm) implant was superimposed on tooth positions from the right first premolar to left first premolar on reformatted cross sectional mages of maxillary anterior teeth. For the first trial, the implant was positioned following the alveolar bone axis. Utilizing Invivo 5 Software (Anatomage), the proximal overlaps between superimposed implants were evaluated at successive vertical steps of 2.5 mm. The prospective crown angulation or PCA (defined as the angulation between the crown axis and alveolar bone axis) was measured. The inter-canine distance across the arch, the palatal plane length and the palatal bony angulation (defined as the angulation between the palatal surface and the alveolar bone axis) were also measured. For the second trial, implant positioning followed a prosthetic driven position; the crown axis. The crown axis was defined as a line drawn from the midpoint of a line between the mid buccal/lingual CEJ to the incisal edge. The crest height and the apical height at which the implant's 1mm sleeve penetrated the buccal wall were calculated. RESULTS: The implant position at the central incisor and lateral incisor presented the highest percentage of overlap in both the biologically and prosthetically driven positions. The prospective crown angulation was higher at the location of the lateral incisor compared to the central incisor and canine position. The association between the remaining anatomical parameters and the prevalence of overlap was analyzed with bi-serial correlation. There was no significant relationship among any of these parameters. When the implant was simulated in a prosthetically driven position, the lateral incisor implant position frequently showed perforation at 5mm apical to the buccal crest margin demonstrating this position as highly sensitive. SUMMARY: The data demonstrated that the constriction of the alveolar bony volume in the anterior maxilla could affect implant placement. Understanding this bone morphology suggests a major limitation in the central/lateral positions which might require bone grafting. A new unique reference plane was utilized for this study. / 2018-09-28T00:00:00Z

Purpose: The purpose of this study is to evaluate how implant-supported fixed dental prosthesis (FDP) restorations with a cantilever at abutment level resist fatigue by dynamic loading and thermocycling depending on the fixture diameters.   Material and method: The study involved two groups with three specimens in each group, based on the diameter of the fixture, 3.5 or 5.0 mm (D3.5 and D5.0). The specimens consisted of two ASTRA TECH platforms, either 3.5 mm or 5.0 mm, 20°Uni Abutments, and a standardized milled CoCr FDP at abutment level with a cantilever. A mounting jig was designed and 3D printed. The specimens underwent a dynamic fatigue test with thermocycling, 5°C and 55°C, and a 250 N load at a frequency of 1.5 Hz for maximum 6×10⁵ cycles, until the specimen either fractured or displayed visible deformation. Fractured specimens were examined under microscope.    Results: In group D3.5, one specimen survived 600,000 cycles without loosening or fracturing, one displayed screw loosening, and one screw fracturing. In group D5,0, two specimens displayed screw fracturing and one screw/abutment loosening.   Conclusions:  · Implant-supported FDP restorations with a cantilever at abutment level tend to resist fatigue better with a larger fixture diameter than with a smaller fixture diameter. · Fixtures with a diameter of 5.0 mm show higher tendency for screw fracturing and loosening compared to fixtures with 3.5 mm.  · More extensive studies regarding implant-supported FDP restorations with cantilever at abutment level and different fixture diameters are required to confirm the results. / Syfte: Syftet med studien är att utvärdera hur implantat-förankrade bro-konstruktioner på distansnivå med frihängande led motstår utmattning genom dynamisk belastning och termocykling beroende på fixturens diameter.   Material och metod: Totalt framställdes två grupper beroende på fixturens diameter, 3,5 eller 5,0 mm, med tre provkroppar per grupp (D3,5 och D5,0). Provkropparna bestod av två fixturer motsvarande position 34 och 35 och ett frihängande led på 36 med plattformarna ASTRA TECH 3,5×9,0 mm eller 5,0×9,0 mm inkluderat distanser 20° Uni Abutment och standardiserade frästa broar i CoCr på distansnivå. Ett dynamiskt utmattningstest genomfördes med hjälp av tuggsimulator med samtidig termocykling 5°C och 55°C. Belastningen på 250 N applicerades på det frihängande ledet under maximalt 6×105 cykler med 1,5 Hz. Provkropparna kontrollerades visuellt och taktilt var 50 000:e cykel för att undersöka om fraktur, deformation eller påverkan på skruvförband uppstått. De frakturerade provkropparna undersöktes i ljusmikroskop för att analysera frakturytor och eventuella deformationer.   Resultat: I grupp D3,5 klarade en provkropp 600 000 cykler utan att lossna eller frakturera, en fick skruvlossning och en fick skruvfraktur. I grupp D5,0 fick två provkroppar skruvfraktur och en fick skruv-/distanslossning.  Slutsats:  · Implantat-förankrade bro-konstruktioner på distansnivå med frihängande led tenderar att motstå utmattning bättre med mindre fixturdiameter än med större fixturdiameter. · Fixturer med diameter 5,0 mm visar större tendens för skruvfrakturer och skruvlossning jämfört med fixturer med 3,5 mm. · Mer omfattande studier beträffande implantat-förankrade bro-konstruktioner på distansnivå med frihängande led och olika fixturdiametrar krävs för att säkerställa resultaten.