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ePaper created 2016-09-05, 09:33:59 | version 1.38.0
non-surgical treatment study | 35 roots 3 2016 no use as prosthetic post and non-molar. In their studies, crowned teeth with or without build-up pin showed the lowest extraction risk versus all other researched variables, crowned teeth without build-up pin simultaneously featured the lowest failure risk. Crowns offer a high fracture protection andareanexpensiveinvestment,wherethepatient does not like to separate from. It has to be consid- ered though that crowning of teeth is preceded by an estimation of the survival prognosis6 and the better case material will be considered first when it comes to crowning. Regarding the incidents of perforation and frac- tured canal instrument, the author found evidence from Ng et al.28 in the survival literature, where 76 (4.7 %) of 1,617 cases were subject to perforation and 105 cases (12.2 %) out of 858 secondary root canal treatments subject to fracture of a canal in- strument. The Cox regression proves a 3.7-fold ex- traction risk for perforations, for the cases with fractured canal instrument a 3.1-fold extraction risk.Marquisetal.29 added11fracturedcanalinstru- ments and 18 perforations in 369 endodontic cases to the intraoperative complications which affect thesuccessresult.Theirownstudyproveda2.5-fold extractionanda8.4-foldfailureriskforviafalsaper- forations. In case of fractured canal instruments the risk of extraction increased 1.3 times and the risk of failure to 2.2 times. Conclusions More than 8,000 endodontic primary cases had beenobservedforupto25years.Qualityandlengthof RF, the type of restoration, the fracture of root canal instruments and the incident of perforation were re- sponsible for the failure and extraction risk. The posi- tion of the tooth, age and social status had an influ- ence on extraction frequency, the pulp state and the operator on the failure frequency. A symptom-free tooth remaining in situ of 73.2 % after 10 years and 51.5 %after20yearsspeaksforasuccessfulendodon- tic treatment therapy under practice conditions._ Acknowledgment: The author would like to thank Dr rer. nat.MonikaKrinerforperformingthestatistics. Editorial note: A list of references is available from the publisher. contact DrRobertTeeuwen BerlinerRing100 52511Geilenkirchen Germany robteeuwen@t-online.de Case 4 Fig.15: Pre-op X-ray (1992). Fig.16: Post-op X-ray (1992). Fig.17: Before RCT (15.06.1992): fistula. Fig.18:After N2-RF (01.07.1992): fistula diminished. Fig.19: Control X-ray (1998). Fig.15 Fig.17 Fig.18 Fig.19 Fig.16 32016