Retention force of overdenture retained with telescopic crowns – a comparison of polyether ether ketone and zirconia ceramic telescopic crowns

Abstract

Introduction/Objective. Recently, new materials for double crowns have been introduced, such as zirconia and polyether ether ketone (PEEK). However, some characteristics of these materials, such as retentive force and duration of “settling in phase,” have not been investigated sufficiently. During the “settling in phase,” telescopic overdenture has not yet achieved its definitive retention force, and it can be harmful for periodontal tissue if the value is above optimal for a long period of time. The objective was to measure the in vitro overall pull-off force of telescopic crowns where primary crowns were made from zirconia ceramics and a survey of the “settling in phase” duration. Methods. Forty zirconia primary telescopic crowns were produced on prepared canine teeth. Twenty secondary crowns were of PEEK and other 20 of zirconia with electroplated gold copings. The pull-off force measurements were conducted utilizing a dynamometer until a constant value was obtained. Results. The specimens of the PEEK group showed higher initial retentive force values. Settling in phase was finished between 800 and 900 cycles of separation for both groups. Comparing the value of the pull-off force between individual different cycles, a statistically significant reduction was recorded up to the 800th cycle, while between the 800th and the 900th cycle there was no difference. Conclusions. The settling in phase was finished between 800 and 900 cycles of separation in both groups. Final retentive force values for both tested telescopic groups were in the optimal range which is 5–9 N per one telescopic crown.

Uvod/Cilj Poslednjih godina uvedeni su u praksu novi materijali za dvostruke krune, kao što su cirkonija i polietereterketon (PEEK). Međutim, neke karakteristike ovih materijala nisu dovoljno ispitane, kao što su retenciona sila i trajanje "faze uhodavanja". "Faza uhodavanja" je inicijalni period upotrebe teleskopske proteze kada finalna retenciona sila još uvek nije postignuta, i može imati štetni uticaj na parodontalno tkivo ako su u tom periodu sile previsoke i predugo traju. Cilj je bio da se izmeri in vitro ukupna sila razdvajanja teleskopskih kruna, gde su primarne krune izrađene od cirkonijumske keramike, i ispitati trajanje faze uhodavanja. Metode Četrdeset primarnih teleskopskih kruna od cirkonijumske keramike je izrađeno na preparisanim očnjacima. Dvadeset sekundarnih kruna je izrađeno od PEEK-a, i još 20 kruna od cirkonije sa galvanizovanim zlatom. Za merenje sile razdvajanja korišćen je dinamometar. Spajanje i razdvajanje teleskopskih kruna i merenje sile razdvajanja je vršeno dok nije dobijena konstantna vrednost. Rezultati Uzorci iz grupe PEEK pokazali su višu inicijalnu vrednost retencione sile. Faza uhodavanja je završena između 800 i 900 ciklusa razdvajanja kod obe grupe. Kada se uporede individualne vrednosti sile razdvajanja između različitih ciklusa, statistički značajno smanjenje je zabeleženo do 800. ciklusa, dok između 800. i 900. ciklusa nije bilo razlike. Zaključak Faza uhodavanja je završena između 800 i 900 ciklusa razdvajanja u obe grupe. Finalna retenciona sila kod obe testirane grupe pokazala je optimalne vrednosti, koje iznose 5-9 N po teleskopskoj kruni.