Tooth Root

Replacement of lost teeth using oral implants is an accepted treatment modality with well-documented high long-term success rates. Conventional screw- or threaded cylinder-type implants have been used almost exclusively. Their incongruence with the extraction socket necessitates the use of a barrier membrane or bone augmentation to prevent down-growth of connective tissue or epithelium between the implant and socket. Although some minor changes in implant design have been made, the neck and abutment connection areas have not changed much in the past 30 years. Custom-made root analog implants have been employed clinically in rare instances; however, they yielded failure rates of up to 96% at 1 year of follow-up. So far, ovoid implants are the closest in design regarding resemblance to the natural tooth anatomy. Root analog zirconia implants with macroretentions were developed and produced for immediate single-stage replacement of missing or hopeless teeth. This article discusses the ...

Stress distribution in human tooth structure can be visualized through the use of Moiré fringes, which has improved the clinical understanding of recently identified anatomical structures in molar occlusal surfaces. This article discusses the concept of a "peripheral rim of enamel" and describes the manifestation of compressive and tensile fractures within the peripheral rim of enamel and dentin. It also emphasizes the benefits of microdentistry techniques and minimally invasive preparation designs in the long-term preservation of the natural tooth structure.

A mandibular first molar with more than four canals is an interesting example of anatomic variations, especially when four of these canals are located in distal roots. This report describes a case of a mandibular first molar with six canals (two mesial and four distal canals in two distal roots). The canals were equipped with a K-file and irrigated with NaOCl (5.25%) and normal saline as the final irrigant. The canals were filled laterally with gutta percha and AH26 sealer (De Trey, Dentsply, Switzerland). This case shows a rare anatomic configuration and points out the importance of looking for additional canals.

Dental trauma can lead to injuries in teeth and their supporting structures, which occurs most commonly in young patients and varies in severity from enamel fractures to avulsions. Root fractures are relatively uncommon among dental traumas, mostly affecting the permanent dentition. It has been reported that root fractures can undergo healing, whereas pulp necrosis can also occur.In this report, we present a case of the utilization of cone-beam computed tomography (CBCT) in the detection of possible cervical or internal resorption secondary to a mid-horizontal fracture in a 36-year-old male patient. The fractured teeth spontaneously healed and were diagnosed radiographically after 28 years. Initially, conventional radiographs showed fractured fragments with radiolucent lines. Because of possible invasive cervical resorption and doubt over internal resorption in the conventional images, it was decided to examine the teeth with cone-beam computed tomography with three-dimensional reconstructions.The images clearly showed the displaced fragments of the root fracture. Despite the appearance in the conventional radiograph, no evidence of cervical or internal resorption was detected in the teeth other than the healed root fracture.It was concluded that CBCT images should be obtained for root fractures, especially those in which cervical or internal resorption is suspected from routine conventional radiographs.

Abstract: Mini-implants and mini-screws are commonly used in orthodontics to provide extra anchorage. One potential insertion site is between the roots in the alveolar process, which results in a risk of damaging the roots of neighbouring teeth. In an animal-experimental study, 20 mini-screws (bracket screw bone anchors, BSBAs) were inserted into the mandible of five beagle dogs. Each dog received two BSBAs in each lower quadrant, between the roots of the second and third, and third and fourth premolars. Sequential point labelling was performed every 6 weeks with vital stains, and apical X-rays were taken every 6 weeks. Radiographic examination demonstrated damage at three roots because of insertion of the BSBAs. Histological examination at these three roots demonstrated an almost complete repair of the periodontal structure (e.g. cementum, periodontal ligament and bone) in a period of 12 weeks, following removal of the screws.Des mini-implants et des mini-vis sont habituellement utilisés en orthodontie pour apporter un ancrage supplémentaire. Un site d'insertion potentiel est entre les racines dans le processus alvéolaire qui résulte en un risque de dégradation des racines des dents avoisinantes. Dans une étude expérimentale animale, vingt mini-vis (Bracket Screw Bone Anchor, BSBA) ont été insérées dans la mandibule de cinq chiens beagle. Chaque chien a reçu deux BSBA dans chaque quadrant inférieur, entre les racines des deuxièmes et troisièmes, et troisièmes et quatrièmes prémolaires. Du marquage par point séquentiel a été effectué toutes les six semaines avec des colorations vitales et des radiographies apicales qui ont été prises toutes les six semaines. L'examen radiographique a démontré les dégâts au niveau de trois racines dûs à l'insertion de BSBA. L'examen histologique de ces trois racines a démontré une réparation quasi complète de la structure parodontale (c.-à-d. le ciment, le ligament parodontal et l'os) après une période de 18 semaines suivant l'enlèvement de ces mini-vis.Mini-Implantate und Mini-Schrauben werden oft in der Orthodontie verwendet, um eine extra Verankerung zu gewährleisten. Eine mögliche Implantationsstelle liegt zwischen den Wurzeln im Alveolarkamm. Dabei besteht das Risiko, die Wurzeln von Nachbarzähnen zu verletzen. In einem Tierexperiment von 20 Mini-Schrauben (Bracket Screw Bone Anchors, BSBAs) in die Unterkiefer von 5 Beagle Hunden eingesetzt. Jeder Hund erhielt 2 BSBAs in jedem Unterkieferquadranten, eines zwischen den Wurzeln des zweiten und dritten und eines zwischen den Wurzeln des dritten und vierten Prämolaren. Alle 6 Wochen wurde eine sequentielle Punktemarkierung mit Vitalfarben durchgeführt und es wurden alle 6 Wochen apikale Röntgenaufnahmen angefertigt. Die radiologische Untersuchung zeigte Verletzungen bei 3 Wurzeln durch das Setzen der BSBA`s. Die histologische Untersuchung dieser 3 Wurzeln zeigte eine fast komplette Reparatur der parodontalen Strukturen (mit Zement, Parodontalligament und Knochen) in einer Zeitspanne von 18 Wochen nach Entfernung der Schrauben.Los miniimplantes y los minitornillos son frecuentemente usados en ortodoncia para suministrar un anclaje extra. Un lugar potencial de inserción se encuentra entre las raíces en el proceso alveolar, lo que resulta en el riesgo de dañar las raíces de los dientes vecinos. En un estudio experimental animal se insertaron 20 minitornillos (Tornillos Óseos de Anclaje para Bracket, BSBAs) en la mandíbula de 5 perros beagle. Cada perro recibió 2 BSBAs en cada cuadrante inferior, entre las raíces del segundo y tercer, y tercer y cuarto premolar. Se llevó a cabo marcado puntual secuencial cada seis semanas con tinción vital y se tomaron radiografías apicales cada seis semanas. El examen radiográfico demostró daños en 3 raíces debido a inserción del BSBAs. El examen histológico en esta tres raíces demostraron una casi completa reparación de la estructura periodontal (e.a. cemento, ligamento periodontal y hueso) en un periodo de 18 semanas, tras la retirada del tornillo.

Abstract. Many well designed clinical studies have established the effectiveness of periodontal therapy. Surgical procedures have been shown to be effective in treating periodontitis when followed by appropriate maintenance care. Scaling and root planing alone have recently been compared to scaling and root planing plus soft tissue surgery in several longitudinal trials. A review of the literature indicates several important findings including a loss of clinical attachment following flap procedures for shallow (1–3 mm) pockets and no clinically significant loss after scaling and root planing. These studies also generally report either a gain or maintenance of attachment level for both procedures in deeper pockets (≥4 mm). For these pockets, neither procedure has been shown to be uniformly superior with respect to attachment gain. All reports indicate that both treatment methods result in pocket reduction. However, the literature also indicates that scaling and root planing combined with a flap procedure results in greater initial pocket reduction than does scaling and root planing alone. This difference in degree of pocket reduction between procedures tends to decrease beyond 1–2 years. It has been shown that both treatment methods result in sustained decreases in gingivitis, plaque and calculus and neither procedure appears to be superior with respect to these parameters.Additional data from the study at the University of Minnesota indicate that similar results are maintained up to 6 1/2 years following active therapy. Pocket depth did not change for shallow (1–3 mm) pockets treated by either scaling and root planing alone or scaling and root planing followed by a modified Widman flap. For pockets 4–6 mm, both treatment procedures resulted in equally effective sustained pocket reduction. Deep pockets (≥ 7 mm) were initially reduced more by the flap procedure. After 2 years, no consistent difference between treatment methods was found in degree of pocket reduction. However, as compared to baseline, pocket reduction was sustained to 6 1/2 years with the flap and only 3 years with scaling and root planing alone. After 6 1/2 years, sustained attachment loss in shallow (1–3 mm) pockets was found after the modified Widman flap. Scaling and root planing alone in these shallow pockets did not result in sustained attachment loss. For pockets initially 4–6 mm in depth, attachment level was maintained by both procedures but scaling and root planing resulted in greater gain in attachment as compared to the flap’at all time intervals. Treatment of pockets ≥ 7 mm in depth by either procedure resulted in a sustained gain in attachment with no difference between procedures.The results of these studies indicate that both scaling and root planing as well as scaling and root planing combined with a flap procedure are effective in treating periodontitis over time up to 6 1/2 years. Individual variations among patients were noted. Decisions for or against soft tissue surgery must be made on the basis of individual patient considerations.

Root perforations that result in a communication of the root space with the periodontal tissues occasionally occur during endodontic procedures. They may be induced iatrogenically, by resorptive process, or by caries. Identification of root perforations is possible by direct observation of bleeding, indirect bleeding assessment using a paper point, radiography, and an apex locator. Prognosis of a tooth with root perforation depends on the time lapsed before obturation of the perforation, location and size of the lesion, and the sealability of the repair material. Perforation defects may be repaired by nonsurgical or surgical techniques. A review of causes, diagnosis, prognosis, and management of root perforations provides information for avoiding, detecting, and treating of such defects.

The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis. Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises) stress and maximum shear stress. The maximum value of total deformation with ...

This study was undertaken to determine the incidence of root fractures during post removal, as well as the methods used and the success rates achieved with various post removal devices and techniques. Patient records from a specialist endodontic practice were examined. A total of 1600 teeth from which posts were removed were identified. These teeth had no preoperative signs or symptoms to suggest root fractures. The incidence of root fractures was determined and a subset of 234 patient records were examined in detail to determine the methods used to remove different types of posts. Only one tooth fractured during post removal (0.06%) and all posts were successfully removed, typically in about 3 min. Most cast posts were removed with an Eggler post remover but some dislodged when the crown was removed; ultrasonics was used occasionally. Most parallel-sided posts were removed with ultrasonics and threaded posts were unscrewed. The Masserann kit and ultrasonics were combined to remove fractured cast posts and some parallel-sided posts. This study indicates that, with good case selection, post removal is a predictable procedure. If appropriate techniques and devices are used for the particular type of post being removed, then root fracture is a rare occurrence.

Hürzeler MB, Zuhr O, Schupbach P, Rebele SF, Emmanouilidis N, Fickl S. The socket-shield technique: a proof-of-principle report. J Clin Periodontol 2010; 37: 855–862. doi: 10.1111/j.1600-051X.2010.01595.x.Hürzeler MB, Zuhr O, Schupbach P, Rebele SF, Emmanouilidis N, Fickl S. The socket-shield technique: a proof-of-principle report. J Clin Periodontol 2010; 37: 855–862. doi: 10.1111/j.1600-051X.2010.01595.x.AbstractAim: Clinical studies have suggested that retaining roots of hopeless teeth may avoid tissue alterations after tooth extraction. Therefore, the objective of this proof-of-principle experiment was to histologically assess a partial root retention (socket-shield technique) in combination with immediate implant placement.Material and Methods: In one beagle dog, the third and fourth mandibular pre-molar were hemisected and the buccal fragment of the distal root was retained approximately 1 mm coronal to the buccal bone plate. Following application of enamel matrix derivate, a titanium implant was placed lingual to that tooth fragment either with or without contact to the buccal tooth fragment and a healing abutment was connected. Four months after implant placement, histological evaluation, and backscatter scanning electron microscopy were performed.Results: All four implants were osseointegrated without any histologic inflammatory reaction and the tooth fragment was devoid of any resorptional processes. On the buccal side, the tooth fragment was attached to the buccal bone plate by a physiologic periodontal ligament. On the lingual side of the fragment, newly formed cementum could be detected. In the areas where the implant was placed into the fragment, newly formed cementum was demonstrated directly on the implant surface.Conclusions: Retaining the buccal aspect of the root during implant placement does not appear to interfere with osseointegration and may be beneficial in preserving the buccal bone plate.Aim: Clinical studies have suggested that retaining roots of hopeless teeth may avoid tissue alterations after tooth extraction. Therefore, the objective of this proof-of-principle experiment was to histologically assess a partial root retention (socket-shield technique) in combination with immediate implant placement.Material and Methods: In one beagle dog, the third and fourth mandibular pre-molar were hemisected and the buccal fragment of the distal root was retained approximately 1 mm coronal to the buccal bone plate. Following application of enamel matrix derivate, a titanium implant was placed lingual to that tooth fragment either with or without contact to the buccal tooth fragment and a healing abutment was connected. Four months after implant placement, histological evaluation, and backscatter scanning electron microscopy were performed.Results: All four implants were osseointegrated without any histologic inflammatory reaction and the tooth fragment was devoid of any resorptional processes. On the buccal side, the tooth fragment was attached to the buccal bone plate by a physiologic periodontal ligament. On the lingual side of the fragment, newly formed cementum could be detected. In the areas where the implant was placed into the fragment, newly formed cementum was demonstrated directly on the implant surface.Conclusions: Retaining the buccal aspect of the root during implant placement does not appear to interfere with osseointegration and may be beneficial in preserving the buccal bone plate.

No clinical studies have been done to explore the relationship of ledging to the clinical practice of endodontics. The purpose of this study was to examine 171 cases completed by third-year dental students and to identify variables that were associated with ledging. A total of 336 canals were examined and tooth number, canal location, working length, the master apical file size, and root canal curvature were recorded. Of 336 canals, 46% were found to have been ledged. Analysis of variance revealed that No. 15 had a significantly higher incidence of ledging. Working lengths and master apical file sizes were not found to be significant variables. The main factor consistently related to the presence of ledges was canal curvature. The number of ledged canals increased significantly after 20 degrees and surpassed the number not ledged after 30 degrees. Multiple regression with the use of the five categories as the dependent variables and ledging as the independent variable resulted in an...