Restoration of Endodontically Treated Teeth Review and Treatment Recommendations
DENTISTRY TOPICS
Restoration of endodontically treated teeth
Carla Castiglia GonzagaI; Edson Alves de CamposII; Flares Baratto-FilhoII,III
I School of Dentistry, Sao Paulo Land Academy – Araraquara – SP – Brazil
II School of Dentistry, Positivo University – Curitiba – PR – Brazil
3 School of Dentistry, Academy of Joinville Region – Joinville – SC – Brazil
Correspondence
ABSTRACT
The restoration of endodontically treated teeth is ane of the most challenging situations of the dentist`southward clinical practice, because it involves procedures related to several areas, such every bit Endodontics, Operative Dentistry, and Prosthetics. These restorations aim to replace the structures lost during endodontic surgery and access to both the pulp chamber and root culvert system during the instrumentation, likewise every bit the removal of the carious tissue and temporary restorations. It is likewise important to remember that the prognosis of endodontically treated teeth depends not simply on endodontic handling success itself, but also on the amount of remnant tooth tissue and the definitive restoration that will be placed onto the dental element.
Keywords: Intraradicular posts; endodontically treated teeth; restoration.
Effects of the endodontic treatment on tooth structure
Devitalized teeth due to endodontic treatment prove some different features compared with vital teeth. This occurs because these teeth, generally, present previous history of carious lesions (pocket-size or very extensive), previously performed restorative treatment, eventual fractures and traumas, also as the endodontic therapy itself.
To plan and perform the restorative treatment of endodontically treated teeth, properly, it is important that the dentist know these alterations and their effects, predicting possible intercurrences and planning the nearly right approach for each example treatment.
Resistance loss and fracture risk
It is well established that teeth undergoing endodontic handling have smaller resistance and higher fracture risk. These molar fractures are relatively frequent in daily clinical practice. Notwithstanding, information technology is of import highlighting that the increase of fracture susceptibility does not direct depend on the endodontic treatment itself. Other factors can effectively contribute to this miracle, for example, loss of crown construction and tooth-reinforcing structures, dentin dehydration, deleterious effects of irrigant solutions and intracanal medications on dentin, and reduction of propioceptive response.
Generally, these teeth suffer a swell book loss of coronal and root dentin due to factors, such as caries, and previous endodontic treatments or restorations. This dentinal tissue volume loss itself can lead to the weakening of remaining tooth structure, which get more prone to fracture occurrence. Additionally to book loss, during more extensive carious lesions, important tooth-reinforcing structures are besides lost, e.g., marginal ridges and pulp chamber roof, farther contributing to the weakening of molar remnant.
Over the years, the increment of endodontically treated teeth's fracture susceptibility has been attributed to the increment of dentinal fragility due to humidity loss. During endodontic treatment, pulp tissue (which presents hydrophilic features) is removed; root canal lumen and dentinal tubules are disinfected and dehydrated prior to obturation. Therefore, the loss of pulp tissue's h2o content and gratuitous h2o of root dentinal surface, dentinal porosities and tubules may contribute to increment the biomechanical damage of endodontically treated teeth. Literature has reported that dentin'south moisture content of endodontically treated teeth is almost nine% smaller than that of vital teeth. However, studies take emphasized that, despite of this departure, information technology is important to preserve the greatest possible amount of dentin to clinch the structure integrity of teeth undergoing endodontic therapy. This corroborates the fact that tooth structure loss is the chief reason for increasing the fracture susceptibility of endodontically treated teeth.
At concentrations varying from 0.5-5.25%, sodium hypochlorite is ordinarily used as irrigant solution during endodontic therapy to pulp tissue dissolution and root canal disinfection. Literature reports several sodium hypochlorite side effects on dentin's physicochemical properties (flexural strength, modulus of elasticity, and microhardness). Additionally, to assure a fast and complete disinfection, some clinicians change the concentration, volume, and flow rate of irrigant solutions, as well as their temperature and expiration dates. Such alterations aggravate sodium hypochlorite's side effects on root canal dentin, increasing the possibility of damages.
Ethylenediaminetetraacetic acid (EDTA) is also an endodontic irrigant solution used to remove the smear layer formed afterwards root culvert instrumentation. Similarly to sodium hypochlorite and other acids, EDTA is too capable of affecting dentin past decreasing its hardness, for example. Studies have as well demonstrated that, when used together, EDTA and sodium hypochlorite create defects on dentin and decrease its mechanical properties, due to the removal of the inorganic and organic phases. These evidences signal that the intensive employ of irrigant solutions at high concentrations and some intracanal medications tin deleteriously affect dentin's physicochemical properties, which may lead to dentinal substrate weakening, locally.
In vital teeth, proprioceptive sensibility limits the load applied on dental elements. However, there are evidences that pulpless teeth show reduced levels of proprioception, consequently issue in decreasing of normal protection reflex. Tooth tissue loss inherent to endodontic treatment promotes a significant subtract of tooth'southward proprioceptive response, which can contribute to increase the susceptibility to cracks and fractures.
Colour changes and translucency subtract
Endodontically treated teeth oftentimes show color alterations, and, patients were non aesthetically satisfied when these occur in their anterior teeth. Tooth concealment is mainly acquired by restorative materials left inside pulp bedchamber, after endodontic treatment. To preclude tooth darkening, any filling material should be carefully removed from pulp chamber and from 2 mm brusque of enamel-cementum junction. Additionally, filling materials containing iodoform or argent are more decumbent to cause tooth color change.
Restorative handling planning of endodontically treated teeth
Restorative treatment of endodontically treated teeth may vary, ranging from a relatively small straight restoration to more complex indirect restorations involving the placement of an intraradicular mail service and core and the indirect restoration itself.
Some factors may directly influence on the option for the restoration type, e.m., the corporeality of coronal remnant after endodontic treatment and patient's prosthetic need. Also, the clinician should verify whether the molar would be used as a removable or fixed partial denture abutment. Moreover, the molar's periodontal and supporting tissues status should be too checked.
Information technology should be clear that, the restorative treatment planning of tooth undergoing endodontic therapy must be carefully executed and, sometimes, it would involve a multidisciplinary team.
Restoration of endodontically treated teeth
The best period to perform the restoration of endodontically treated teeth is a very controversial issue, mainly those presenting a periapical lesion. Therefore, in these cases, the restorative treatment can be either performed immediately after endodontic treatment ending or later a certain time period to look the regression of periapical lesions. Studies evaluating the time influence on definitive restorations of endodontically treated teeth take shown that the prognosis of teeth with permanent restorations (straight amalgam or composite resin restorations and indirect restorations with or without intraradicular post and core) placed immediately after endodontic handling ending was better than molar receiving temporary restorations (zinc oxide and eugenol cements and plaster-based cements). Literature has also reported that marginal microleakage of teeth with temporary restorations is higher than teeth with definitive restorations, suggesting that definitive restoration should be performed as before long equally possible afterwards endodontic therapy conclusion.
To prevent root canal system contamination inside the period betwixt endodontic treatment catastrophe and the beginning of tooth's definitive restoration is a key factor for success. Therefore, the dentist should exist concerned because bacterial contamination is considered an important cause of further problems in endodontically treated teeth.
Some recent studies have indicated that either coronal restoration or apical sealing microleakage negatively affects the endodontic treatment success. Coronal sealing importance has been increasingly recognized by literature. Currently, information technology has been suggested that apical microleakage may not exist the most of import factor for endodontic treatment failure and that coronal microleakage is the most likely cause and the key factor for endodontic and restorative handling success or failure.
Temporary restoration after endodontic treatment
Molar's restorative treatment later endodontic therapy should exist initiated every bit soon as possible. However, because this is not possible in some cases, an adequate temporary restoration is extremely important to assure an efficient sealing and avoid contamination. To perform their function properly, temporary restorative materials should present, among other features, high mechanical resistance, good marginal sealing, depression solubility, thermal expansion coefficient shut to tooth tissues, aesthetics, as well as easy handling, insertion and removal from the training.
When immediately restoration is non possible, a temporary restorative textile should be used to prevent root canal arrangement from saliva and microorganism contamination. Restorative materials showing any bonding mechanism to tooth construction, such as composite resins and glass ionomer cements (conventional or resin-modified) are skillful options. Nevertheless, the most common materials employed for this purpose are temporary restorative materials, such as zinc oxide eugenol cements (eastward.g., IRM) or plaster-based materials that are premixed and then cured when in contact with saliva (eastward.m., Cavit, Cimpat or Cotosol). It is important noting that temporary restoration, mainly identify into greater admission cavities or into teeth presenting greater coronal devastation, does not adequately protect the tooth against fracture occurrence.
In some situations, to better root canal arrangement sealing, the dentist can use an intermediary procedure. In this case, root culvert openings should exist advisedly cleaned with a circular bur of compatible diameter and pulp chamber's floor cleaned from all gutta-percha and endodontic cement excess. Post-obit, pulp sleeping room's floor should exist sealed through bonding technique and blended resin or conventional/resin-modified glass ionomer cement. Next, temporary restoration is placed, with or without using a cotton fiber pellet within pulp chamber. Ideally, a sparse layer of restorative material should exist placed for sealing, allowing that root canal openings and gutta-percha exist easily seen. This sealing type protects root canal system against contamination until the restorative phase is executed.
In some cases, it is possible that endodontic handling admission exist executed through a full crown. Therefore, if the crown seems to be clinically acceptable, at endodontic treatment catastrophe the caries presence must be checked and the temporary material should only be placed without any sign of this pathology. If caries is present, the crown and caries removal should be carried out to allow the temporary restoration placement. In some cases, nevertheless, crown'southward removal is not possible, consequently the most part of the carious tissue must be removed through endodontic admission and a good temporary sealing should be executed. Accordingly, restorative handling should be completed as presently as possible so that both the carious tissue remnant and the crown be removed, diminishing root canal system and endodontic treatment contagion.
Thus, literature has suggested that the prognosis of endodontically treated teeth can exist improved by a good root canal sealing and decreasing of bacteria and oral fluids' microleakage to perirradicular areas. Moreover, literature has indicated that the tooth should exist restored just after endodontic handling catastrophe because periapical tissues' wellness depends more on the temporary restoration than on endodontic treatment technical quality. It is important to highlight that endodontic retreatment should be considered in teeth which lost their coronal sealing or presented issues in their restorations, past any reason. Based on the penetration rate of bacteria and their endotoxins, accurately filled root canals of teeth which have lost their coronal sealing and have been exposed to oral surround for a period longer than two to iii months demand to be submitted to endodontic retreatment prior to definitive restoration placement.
Definitive restoration after endodontic treatment
Definitive restoration of endodontically treated teeth aims not only to promote coronal sealing and avoid microleakage/contagion, merely as well to supersede the lost tooth construction and protect the remnant tooth structure, mainly against fractures. This restorative stage may involve the placement of i or more of the post-obit elements: intraradicular mail service and cadre and coronal restoration itself. Yet, not all teeth undergoing endodontic handling will necessitate the placement of intraradicular mail and core/indirect restoration (due east.k., total crown). The amount of coronal remnant is one of the main factors to be analysed during the restorative pace of endodontically treated teeth. Therefore, a conscientious evaluation of each case should be executed to signal the best restorative treatment option.
In some cases where the apply of intraradicular postal service and core is necessary and it is installed immediately after endodontic procedure, definitive restoration should also be immediately executed, due to the difficulty of maintaining the temporary sealing. In vitro studies have demonstrated that provisionally restored teeth exhibiting an intraradicular post preparation present contamination similar to those not restored yet.
Teeth exhibiting little or no coronal remnant
Teeth exhibiting little or no coronal remnant require the use of intraradicular post and core to retain the coronal restoration.
Quite some time ago, it was believed that intraradicular post and core should be placed after endodontic therapy to reinforce tooth remnant. Nevertheless, currently, studies have been unanimous in affirming that intraradicular postal service and core does non reinforce tooth remnant and it can even weaken the tooth due to the necessity of preparation and additional dentin removal for its placement, leading to college root fracture susceptibility. These studies accept already suggested that intraradicular post and core should exist used but when in that location is insufficient coronal remnant to retain and support the final restoration.
One time intraradicular post and core does non reinforce an endodontically treated tooth and tooth preparation may increment the hazard of root fracture and treatment failure, the decision of using an intraradicular mail service and core, at any clinical situation, should exist advisedly performed. In about cases, endodontic treatment is executed due to trauma, extensive caries, or restorative procedures. Appropriately, the evaluation on the decision of utilizing an intraradicular post and core is based on the corporeality of audio tooth remnant and on the adequacy of supporting a definitive restoration or filler core.
Intraradicular post and cadre employment is too dependent on the tooth type. Several endodontically treated molars do not require an intraradicular mail service and cadre because they testify more coronal remnant and a larger lurid bedroom to retain a filler core. Additionally, molars are more than subject to vertical forces, due to their dental curvation position and functional movements, which can lead to a lower necessity of intraradicular post and cadre. Notwithstanding, when information technology is required, intraradicular post and cadre should exist placed at the largest and more direct root canal to avert root weakening during preparation, as well as perforation of curved root canals. Lower molars' distal canal and upper molars' palatal canal by and large are the most indicated for intraradicular post and core placement. When the retention, mainly in cast metal dowels, is notwithstanding insufficient after the preparation of a single root canal or there is both a lack of locking and rotation of the coronal portion, boosted locking measurements should be considered.
Generally, bicuspids showroom less coronal remnant and smaller lurid chambers to retain intraradicular post and core afterward endodontic treatment than molars. Withal, they more frequently crave this approach. Additionally to their root taper and curvature, several bicuspid roots are thin at mesiodistal management, and some roots may present proximal invaginations. These factors show that the anatomical features of each tooth should be carefully considered during intraradicular post and core preparation to avoid intercurrences and iatrogeny, such as root perforations.
Some studies bespeak that intraradicular post and core may not exist required in endodontically treated inductive teeth exhibiting fiddling coronal construction loss, indicating that these teeth could be restored directly through bonding technique and composite resin. However, if there is a demand of a full crown placement subsequently endodontic therapy due to significant loss of coronal remnant, intraradicular post and core will be required. Again, attention should exist given to the anatomical features of each tooth blazon. Lower incisors, for example, show thin molar roots at mesiodistal direction, which tin can make its intraradicular grooming more difficult. By and large, anterior teeth should resist to lateral and shear forces, and, their pulp chambers are small to retain fairly a last indirect restoration without a mail service and core. However, information technology is highlighted that the amount of coronal remnant and molar's functional requirement determines if an anterior tooth volition or will not need the use of intraradicular postal service and core.
Intraradicular posts
The main goal of intraradicular posts is to retain and back up the final restorations of tooth presenting extensive loss of coronal structure. Cases in which they are correctly indicated, caution should exist taken during intraradicular preparation considering, although relatively uncommon, intercurrences may occur, such as: perforation at root'due south apical portion or at flattened areas of some roots' medium third. Intraradicular post installation may also increase the chances of root fracture and restorative treatment failure, especially if an excessive radicular dentin habiliment during preparation is executed. Thus, intraradicular post installation is recommended only when other options to retain a cadre or final restoration cannot be used.
Intraradicular posts tin be classified in several manners. In a didactic and uncomplicated style, they can be divided into two large groups: customized or anatomical and pre-fabricated. Among the customized posts, cast posts are the virtually known and used in daily clinics, mainly in cases with piffling or no coronal remnant. Currently, due to aesthetics requirements, customized glass fiber posts and composite resin filler core have also been used in inductive teeth, at daily practice.
Cast metal dowels present a great versatility, because they can be obtained through several metal alloys. Additionally, since they are customized, they allow the utilize of a thin layer of luting cement and evidence high resistance, every bit well every bit clinical longevity proved by scientific evidence. Still, they exhibit some features unfavorable to molar remnant preservation, such every bit irregular stress dissipation and stress concentration at apical area favoring the wedge outcome, the possibility of oxidation and corrosion, facilitating microleakage and tooth construction pigmentation. Currently, aesthetics is also 1 of the main disadvantages of cast metal dowel use, mainly in anterior teeth receiving all-ceramic crowns with high translucency.
Information technology is important highlighting that cast metal dowels demand at least two appointments (one comprising the preparation, and dowel's impression or modeling; other comprising dowel'due south proof, adjustment, and cementation), which effect in longer chairtime, as well as laboratorial procedures and costs. Betwixt the appointments, it is necessary to place a temporary crown and post, which can increase the possibility of root canal systems contagion. Ideally, it would be interesting that intraradicular dowels be installed at one date, as prefabricated posts. However, despite their disadvantages, endless long-term studies accept reported high success rates for cast dowels, if they are well indicated and well constructed.
The increasing demand for aesthetic intraradicular posts resulted in the advent of prefabricated ceramic posts, in 1990. Generally, they are made in zirconium oxide and present physicochemical characteristics such as modulus of elasticity and flexural strength close to metals (i.e., Cosmopost and Cerapost systems). Despite of the practiced mechanical properties, the high modulus of elasticity (which indicates the cloth'due south rigidity, so that, the greater the modulus of elasticity, the greater its rigidity) of both metals and ceramics (raging from 80 and 200 GPa, depending on the metal blend and on the ceramic) may exist related to the relatively high root fracture charge per unit when this blazon of mail is used. Because ceramic posts' modulus of elasticity can reach up to 10 times greater than dentin's modulus of elasticity (about 20 GPa), stress distribution and transference to root during masticatory efforts may negatively influence on the results.
Other of import gene to be considered regarding to the employ of metal and ceramic intraradicular posts is their removal, for example, due to their fracture or endodontic retreatment. Metallic (cast dowels) and ceramic posts removal is a very difficult procedure involving risks, considering these materials present high rigidity and hardness, making hard their clothing by rotary instruments, ultrasound or burs. When performing the wear of posts at their intraradicular portion, attention should be given to clinch that just the mail is worn, avoiding deviations and fifty-fifty perforations.
In an effort to decrease the problems found by the use of intraradicular posts with physicochemical properties very different from those exhibited by dentin, new materials have been introduced into dental marked, for this purpose. Carbon fiber posts gained popularity in the 1990s. Their master advantage would be higher flexibility and modulus of elasticity close to dentin. Too that, because carbon fiber posts can be adhesively cemented to root dentin, it was believed that stresses would be more uniformly distributed on root, resulting in less root fractures.
However, carbon fiber posts exhibit a dark colour. This would be a problem concerning to the restoration'southward aesthetic aspect, as previously discussed. Additionally to carbon fiber posts, other cobweb posts are also available in dental market, including quartz and glass fiber posts, which accept mechanical properties similar to those of carbon fiber posts, but with better aesthetics. Glass cobweb posts are composed of nigh 40% of silica-based glass fibers (fifty to lx% of SiO2), with almost 12 to xviii μm, 30% of resin material (BIS-GMA or epoxy resin) and thirty% of inorganic fillers. Information technology is precisely because of its composition that this type of postal service provides calorie-free refraction and transmission through tooth structure, ceramics or resin, without the demand of opacifying or modifying agents. In comparison with ceramics or metallic posts, cobweb posts are relatively ease to remove through rotary instruments or ultrasound, because the fibers orientation helps to maintain the musical instrument at the correct aligning, avoiding deviations.
Apropos to shape, prefabricated posts can exist parallel or conical. More often than not, conical posts are easier to be installed because of their shape similar to both the root and and then prepared and filled root culvert. Additionally, the conical shape helps in the maintenance of dentin preservation at apical region during preparation, avoiding an additional weakening of the tooth structure to be restored. Also, it is interesting to emphasize that conical posts are less retentive than parallel posts. Yet, clinical studies have shown that, despite of the smallest retentivity when compared with parallel posts, conical posts can be very retentive if they take an adequate length. Apropos to stress distributions, conical posts generate greater stress around all root, while parallel posts generate stress at root apex.
Currently, double-tapered posts have been seen frequently at dental market place. These posts are more than advantageous than the last ii because, at virtually office of their length, they exhibit a low taper, almost existence considered every bit parallel. However, at apical portion, they show a college taper. Due to this shape, they present a college retention and promote a higher preservation of molar structure at apical tertiary; additionally they provide a better stress distribution.
Preparation of intraradicular posts
Regardless of the mail service type to be used, whenever possible, root dentin construction should be preserved at most because the greater the increase of its removal and preparation, the greater the root weakening and fracture possibility. Besides that, prior to root canal desobturation and preparation, the dentist should keep in mind that root diameter may different at buccal-lingual and mesiodistal directions. To make up one's mind the acceptable length and diameter of intraradicular posts, equally well as to prevent the occurrence of root perforations and other intercurrences, it is necessary to consider the following conditions, during preparation: root taper, proximal invaginations, root curvatures and crown/root angle. In most cases, the endodontist performing and then endodontic treatment is the specialist who should execute the intraradicular postal service infinite preparation, because this professional knows meliorate the root canal organisation morphology.
Root canal desobturation and grooming should always exist performed under accented isolation, to maintain the aseptic chain and avoid some possible root canal contagion. Gutta-percha tin can exist initially removed with the assist of a heated instrument or chemical substances. Too, Gates-Glidden and rotary instruments can be used.
During intraradicular grooming, apical sealing should exist kept by maintaining three to half dozen mm of gutta-percha at apical area, considering information technology is important to clinch a good barrier confronting a possible region reinfection. This minimum amount of gutta-percha, in some cases, may limit the post length. All the same, when this occurs, apical sealing is the factor that should prevail. Additionally, in one case the intraradicular grooming is completed, the mail should exist cemented equally shortly as possible, avoiding the possibility of contamination.
Concerning to length, information technology can exist considered that the greater the length the greater the mail'due south retention, although root's amount and shape are also important factors for determining the mail service length. Anatomical limitations exercise not even allow that the greatest post length exist achieved in relation to root length. Therefore, in curved or short root canals, an boosted retention can exist executed through either the luting cement agent or more than parallel mail service designs. As a general rule to determine the ideal intraradicular post length, we tin can cite: the postal service length should exist at least equal to the clinical crown length; the postal service length should exist equal to at to the lowest degree one-half or 2 thirds of the root remnant length; and mail service's root portion should be inserted into at least half of the root supported past alveolar bone. The outset two statements are important to achieve a maximum retention with skillful stress distribution. The last argument, on the other hand, is of import to diminish root fracture possibility because fracture chance increases when this condition is not followed.
Literature has supported the aforementioned statements, since clinical studies betoken that longer posts were associated to college success rates. For example, one study reported failure rates of virtually 2.5% when the post length had been equal to the clinical crown length. Cases in which the post length was equal to one quarter of its respective clinical crown, the failure rates were 10 times greater, reaching 25%. Other interesting study on vertical fractures in endodontically treated teeth revealed that two thirds of the cases had been associated to extremely short posts, simply retained within the roots' cervical third.
It is largely accepted that the mail diameter has little influence on its memory. Nonetheless, larger preparations, evidencing a higher radicular dentin article of clothing, may increase root fracture take a chance. Generally, post width (as well equally preparation) should not exceed one tertiary of the smallest root width, with a minimum of ane to 1.5 mm of root wall around all preparation, respectively for apical and cervical portions.
Cementation of intraradicular posts
Equally same cited the cementation of intraradicular posts should be executed as soon as possible, after root preparation ending. The primary factors influencing on post bonding to radicular dentin include properties, such every bit: high tensile and bond forcefulness, and depression potential for plastic deformation occurrences, microleakage and h2o absorption. Additionally, luting cement amanuensis's handling features during post cementation and caste of polymerization may likewise play an important function in increasing clinical longevity.
The well-nigh used luting cement agents for this purpose are zinc phosphate cement, glass ionomer cement (conventional or resin-modified), and resin cements. From these, zinc phosphate is however 1 of the most unremarkably used for metallic posts, considering information technology has advantages such as: longer working time and compatibility with zinc oxide and eugenol, present in a smashing number of endodontic cements. However, the main disadvantages of this cement are high solubility, especially in the presence of acids, and lack of adhesion to dentin. Conventional glass ionomer cements are also well indicated for metallic postal service cementation, however, despite of adhesion to dentin and fluoride release, these materials are as well soluble and tend to present higher microleakage levels, as well as modulus of elasticity smaller than zinc phosphate cement and dentin. Currently, resin cements accept been very used, although literature has reported conflicting results that may be explained by polymerization inhibition by eugenol (as already mentioned, it is present in some endodontic cements) and by the adhesive technique itself. Even so, despite of the disadvantages, literature has indicated a recent tendency towards to the use of resin cements, considering they may improve the retentiveness, tending to present a smaller possibility of marginal leakage. As well, they provide at least at short fourth dimension, root remnant reinforcement.
Literature has reported that cast metallic dowels cementation with conventional cements, such equally zinc phosphate and glass ionomer, practice non provide root reinforcement. On the other hand, adhesively-cemented intraradicular posts may initially strengthen the root, merely this strengthening is likely lost every bit time goes by, when the molar is submitted to functional tension and through adhesive interface degradation.
Among all same luting cement agents, resin cements are those necessitating more attention regarding to its technique. Cautions initiate presently later on the intraradicular preparation ending, since any residue of gutta-percha and endodontic cement coming from root culvert desobturation should exist removed from dentinal walls to assure an adequate bonding process. Afterward desobturation and grooming, canal walls should be cleaned with a Peeso drill and washed through dental triple syringe and irrigant syringe. Root dentin walls cleaning and washing are extremely important to assure a practiced adhesion, because boding failures occur mainly due to impurities nowadays within root canal. In cases employing a zinc oxide and eugenol-based endodontic cement, literature has reported that a good culvert cleaning after grooming decrease or even eliminate the possibility and occurrence of issues in resin cements' polymerization by interacting with eugenol.
Later cleaning and washing procedures, the removal of the demineralized collagen layer is performed through using a proteolytic agent, such as sodium hypochlorite, aiming to improve resin bonding to root canal walls due to greater penetration of resin tags into dentinal tubules. The bonding protocol itself is and so initiated past applying a full-etching or a cocky-etching adhesive system, always according to the manufacturer'southward instructions. Later on the adhesive protocol, the chemical-cured or double-activated resin cement should be handled, advisedly inserted into root canal, followed by post insertion. When drinking glass fiber posts are used, prior to cementation and after proof, they should be cleaned with 70% booze and undergo silanization.
Filler core
The filler core construction is necessary in cases presenting little or no coronal remnant, allowing thus that the definitive restoration be placed and retained. Several materials can exist used for constructing a filler core. Ideally, they should have properties, such as: loftier tensile and bond strength, biocompatibility, like shooting fish in a barrel handling, bond to the remaining tooth structure, thermal expansion coefficient, shrinkage similar to tooth construction and dimensional stability. Unfortunately, similarly to most of dental restorative materials, none tin can reach all these features. Amalgam, blended resin, and glass ionomer cement are currently the most used materials for constructing filler cores.
Despite of the cracking aesthetic appealing of the current days, constructing has been successfully used for many years. Nevertheless, this material presents as disadvantages a long setting time, which make impracticable its immediate training afterward its condensation and initial crystallization. Additionally, the clinician must be well trained to apply amalgam in extensive or complex restorations, as well as in cases with lilliputian thickness, due to fracture take chances. Concerning to aesthetics, amalgam would not be a expert filler cadre for metallic or metal-ceramic crowns. Still, currently, with the increase of the number of ceramic systems developed and employed, amalgam has not been used equally filler core material, routinely. On the other hand, composite resin and glass ionomer cements have offered more satisfactory aesthetics, mainly in anterior teeth and teeth receiving ceramic crowns or indirect restorations. Among these, composite resins should be the material of choice for constructing filler cores in many clinical situations, instead of glass ionomer cements, considering these latter showroom a low modulus of elasticity, smaller adhesion to dental tissues, relatively difficulty of insertion into cavity without the utilise of a Centrix syringe, and high solubility.
Coronal restoration
In teeth with lilliputian or no coronal remnant, coronal restorations generally involve full crowns, such as metallic, metal-ceramic, or all-ceramic crowns. Cases in which some coronal remnant (due east.g., one wall) is present and can exist preserved, onlay restorations with cusps coverage may exist used in endodontically treated teeth. However, these types of indirect restorations demand the execution of an extensive training and showroom a college cost to patient.
Concerning to cups coverage, literature has indicated that each clinical situation should be carefully evaluated to decide whether this coverage type would be important for the restoration's longevity and clinical success. Fifty-fifty in cases exhibiting fiddling tooth remnant, information technology is recommended that cusps coverage be performed after endodontic therapy, because most of teeth requiring endodontic treatment generally undergo severe damages as a result of extensive carious lesions and/or fracture.
Teeth with intermediary coronal remnant
Clinical situations in which the coronal remnants exhibit approximately one-half of its original volume, their restorations just after endodontic handling may involve the installation of a prefabricated glass fiber mail followed past direct composite resin restoration.
In some cases when tooth-reinforcing structures, such equally marginal ridges, are still nowadays and the tooth displays a deep pulp chamber, we can choose a definitive composite resin restoration only, without the need of an intraradicular post.
Thus, the dentist should evaluate all situations, carefully, to opt by the best restorative treatment for endodontically treated teeth, assuring a good prognosis and higher clinical longevity.
Teeth with keen coronal remnant
In some situations, the endodontically treated tooth does not undergo a dandy coronal structure loss, despite of small preexisting restoration and admission surgery. In these cases, which the tooth shows a great conservation of the coronal structure remnant, the run a risk of fracture is low and the restorative treatment includes only the execution of direct composite resin or amalgam restorations to close the endodontic admission, with very good prognosis.
Immediate dentin sealing
Although this text addresses the restoration of endodontically treated teeth, the repercussion of indirect restoration preparation in vital teeth should be commented, mainly about immediate dentin sealing, issue that has been increasingly discussed on current literature.
Prosthetic preparation of pulped teeth invariably leads to a considerable loss of tooth structure, with exposure of dentin tissue. This dentinal surface itself deserves special attention in the sense of preventing bacterial penetration into dentinal tubules, pulp pathologies and sensibility.
A relatively frequent occurrence in dental offices is post cementation sensitivity after bonding systems apply. This sensitivity is explained by the hydrodynamic theory, in which fluids movimentation through dentinal tubules internal space would exist capable of sensitizing the nervous fibrils, provoking pain. An approach that has been gaining very prominence is the immediate dentinal sealing technique, which consists in dentin hybridization immediately later on the tooth preparation, even prior to the impression procedure. This hybridization acts equally a waterproofing membrane on the freshly-cut tissue, preventing the occurrence of the aforementioned problems. The dentist tin can hands employ this technique with the resources already present in dental role.
The technique consists in employing a bonding organisation on tooth structure following the same bonding protocol used for amalgam direct composite resin restorations.
At this signal, we should highlight some important factors: it is recommended the use of a multipurpose adhesive system, i.due east., presenting split up primer and bail (hydrophobic bonding) agents. This system may be a total carving (acid + primer + bond) or self-etching (acid primer + bail) type. The dandy advantage of cocky-etching systems is that, because dentin etching with phosphoric acid is non necessary, dentin permeability is non increased (because the smear layer is non removed). Past this machinery of action, self-etching systems are less prone to showroom mail-operative sensitivity.
The clinical protocol initiates with the application of the bonding system following the manufacturer'southward instruction. Later the concluding light-curing of the adhesive system, it most superficial layer should be removed by Robinson bristle brush with pumice. The post-obit steps comprise the construction of the temporary restoration and impression procedure. Special circumspection should be taken during the removal of the superficial bonding layer, because otherwise, temporary restoration volition firmly bond to the tooth.
More recently, some authors have indicated the insertion of a composite layer after the application of the adhesive organisation not simply on dentin, but likewise on cervical enamel. In cases displaying subgengival grooming, cervical wall should be repositioned supragingivally by using the cloth, e'er under absolute isolation. To execute this technique, we should choose a micro-hybrid blended resin of regular consistency (normal), avoiding high flow, low viscosity (flowable) resins. This selection is because regular consistency resins present more adequate modulus of elasticity for this clinical situation.
I question that tin can be raised regarding to the cementation step is whether this layer could interfere on the bail strength of the resin cement. Several studies accept demonstrated that, in one case well prepared, this surface becomes highly receptive to the resin cement and shows bail force values higher than those demonstrated by cementations directly on not-sealed dentin.
At the moment of cementation, the previously sealed dentin should be sandblasted with aluminum oxide particles. This procedure volition increase this sealing layer's surface energy, even so, without completely removing information technology. The bonding potential on this surface is very skillful, and the professional should ordinarily follow the cementation protocol proposed by the cement agent'south manufacturer.
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Carla Castiglia Gonzaga
5300, Professor Pedro Viriato de Sousa St. – Campo Comprido
Zip code 81280-330 – Curitiba – PR – Brazil
E-mail: carlacgonzaga2@gmail.com
Source: http://revodonto.bvsalud.org/scielo.php?script=sci_arttext&pid=S1984-56852011000300021
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