Hanjo Hecker

Strategic considerations in treatment planning: Deciding when to treat, extract, or replace a questionable tooth

Prosthodontists face the difficult task of judging the influence and significance of multiple risk factors of periodontal, endodontic, or prosthetic origin that can affect the prognosis of an abutment tooth. The purpose of this review is to summarize the critical factors involved in deciding whether a questionable tooth should be treated and maintained, or extracted and possibly replaced by dental implants. A MEDLINE (PubMed) search of the English, peer-reviewed literature published from 1966 to August 2009 was conducted using different keyword combinations including treatment planning, in addition to decision making, periodontics, endodontics, dental implants, or prosthodontics. Further, bibliographies of all relevant papers and previous review articles were hand searched. Tooth maintenance and the acceptance of risks are suitable when: the tooth is not extensively diseased; the tooth has a high strategic value, particularly in patients with implant contraindications; the tooth is located in an intact arch; and the preservation of gingival structures is paramount. When complete-mouth restorations are planned, the strategic use of dental implants and smaller units (short-span fixed dental prostheses), either tooth- or implant-supported, as well as natural tooth abutments with good prognoses for long-span FDPs, is recommended to minimize the risk of failure of the entire restoration.

Curved versus straight root canals: the benefit of activated irrigation techniques on dentin debris removal

OBJECTIVE The aim of this study was to compare the efficacy of hydrodynamic and ultrasonic-activated irrigation to conventional syringe irrigation in removing dentin debris in straight and curved root canals. STUDY DESIGN Twelve human teeth were selected for study. The root canals of 6 single-rooted premolars with straight canals and 6 molar roots with curved canals were prepared to a size of 45 and split longitudinally. To simulate canal irregularities, 3 standardized holes were cut in 1 canal wall. The canals and holes were then covered with debris. After reassembly, 3 irrigation techniques were compared: syringe irrigation, hydrodynamic irrigation, and ultrasonic irrigation. The amount of debris that remained was evaluated microscopically and graded with a 4-score system. RESULTS The hydrodynamic and ultrasonic irrigation techniques were significantly (P < .001) more efficient as compared with syringe irrigation in both the straight and curved root canals. Ultrasonic irrigation demonstrated a higher efficiency in the straight root canals (P < .01), whereas hydrodynamic irrigation was more efficient in the curved canals (P < .01). CONCLUSIONS In the straight canals, ultrasonic irrigation was the most effective, but in the curved root canals, hydrodynamic irrigation was superior.

Homogeneity and adaptation of endodontic fillings in root canals with enlarged apical preparation

OBJECTIVE The aim was to compare the homogeneity and adaptation of endodontic fillings placed in root canals with wide apical preparation. STUDY DESIGN One hundred twenty root canals were prepared under simulated clinical conditions. The range of apical preparation size was 45 (narrow canals) to 60 (wide canals). The canals were filled using 4 techniques: Thermafil, GuttaFlow, apical cone, and vertical compaction. The root canals were sectioned at 5 levels. The adaptation and homogeneity of the filling were evaluated and statistically analyzed. RESULTS The percentage of canal outline in contact with the filling in the Thermafil group (91.3% [95% confidence interval (CI) 88.8%-93.6%]) was statistically significantly lower than in the other groups. No statistically significant differences were found between GuttaFlow (96.6% [95% CI 95.7%-97.5%]), apical cone (98.6% [95% CI 98.0%-99.3%]), and vertical compaction (98.1% [95% CI 96.5%-99.7%]). Similarly, the percentage of void area in Thermafil group (4.0% [95% CI 2.6%-5.3%]) was statistically significantly higher than in the other groups (GuttaFlow 1.4% [95% CI 0.1%-1.8%], apical cone 1.6% [95% CI 0.7%-2.4%], and vertical compaction 0.1% [95% CI 0.1%-1.8%]). CONCLUSIONS The tested filling techniques/materials provided similar high values for the homogeneity and adaptation to root canal walls after enlarged apical preparation, except for Thermafil at the most apical level.

Determining the apical preparation size in premolars: part III

OBJECTIVE The objective of this study was to investigate cross sections of the apical part of premolar root canals and determine recommendations for their optimal apical preparation size. METHODOLOGY A total of 140 root canals from extracted human premolars (86 maxillary, 54 mandibular) were selected. After preflaring, the electronic working length (WL) was measured to identify where the apical preparation size (APS) should be established. Subsequently, nontapered, noncutting special instruments (SI) were used to reach the WL. The diameter of the largest SI width that reached the WL was defined as d(SI). The roots were apically sectioned at 2 levels, and the diameter of a potential rotary instrument was determined, allowing complete circumferential cutting of the root canal wall for each section. The estimation of APS was then related to d(SI). RESULTS Apically enlarging upper premolars with 2 canals and lower premolars to an individual APS of d(SI) +0.3 mm (6 file sizes) resulted in a 71% to 75% complete preparation of the root canal walls, whereas an enlarged preparation of d(SI) +0.4 mm (8 file sizes) reached 82% to 96%. In upper premolars with a single canal, an APS of d(SI) +0.3 mm completely processed the root canal walls in only 37%, whereas an APS of d(SI) +0.4 mm reached 63%. CONCLUSIONS The APS in 2-canal upper premolars and mandibular premolars should be at least 6 sizes larger than the first apically binding file, whereas in upper premolars with a central canal, the APS should be enlarged to 8 sizes larger. Normally, this implies shaping premolars with 1 canal to #60 to 70 and with 2 canals to #40 to 50.