Periapical periodontitis

Introduction
Inflammation in the periapical area of the periodontal ligament is similar to that occurring elsewhere in the body. It is often accompanied by resorption of bone, and occasionally the root apex, sufficient to be detected radiographically. However, the periapical vascular network has a rich collateral circulation, greatly enhancing the ability of the tissue to heal if the cause of the inflammation is removed. This potential for complete periapical healing, providing the source of irritation is removed, is the basis of endodontic treatment.

Whether the response to irritation in the periodontal ligament is principally an acute or chronic inflammation depends on factors such as the number and virulence of any microorganisms involved, the type and severity of any mechanical or chemical irritant, and the efficiency of the host defences. While it is convenient to describe acute and chronic periapical periodontitis as separate conditions, it must be realized that the tissue reaction to irritation is a dynamic response, often vacillating with time between acute and chronic inflammation. The sequelae are determined by the balance between the nature, severity, and duration of the irritant and the integrity of the defence mechanisms of the patient.

Aetiology

Introduction

The main causes of periapical periodontitis are detailed below.

Pulpitis and pulp necrosis

If pulpitis is untreated bacteria, bacterial toxins, or the products of inflammation will in time extend down the root canal and through the apical foramina to cause periodontitis. When pulp necrosis follows other causes, for example a blow to the tooth damaging the apical vessels, clinically significant periodontitis does not develop, unless bacteria gain access to the necrotic pulp or to the periapical tissues. The possible changes that may occur around the apex of an infected non-vital tooth and their inter-relationships are illustrated in

Changes that may occur around the apex of an infected non-vital tooth

Trauma

Occlusal trauma from, for example, a high restoration, undue pressure during orthodontic treatment, a direct blow on a tooth, and biting unexpectedly on a hard body in food may all cause minor damage to the periodontal ligament and localized inflammation. Traumatic periodontitis is often acute and transitory.

Key points - Periapical periodontitis
dynamic process; inflammation can vary with time
outcome reflects the balance between the nature, duration, and severity of the irritant and the effectiveness of the host defences
bacterial infection of the root canals is the major cause of clinically significant periodontitis
can follow acute traumatic injury to periapical tissues without pulp necrosis; usually transient

Key points - Mnemonic for differential diagnosis of pain of pulpal and periapical origin - LOCATE
Location
Other symptoms
Character
Associations
Timing
Evaluation of other investigations, e.g. pulp vitality tests
 

 Endodontic treatment

Mechanical instrumentation through the root apex during endodontic treatment, as well as chemical irritation from root-filling materials, may result in inflammation in the periapical periodontium. Instrumentation of an infected root canal may also be followed by periapical inflammation as a result of bacteria being forced inadvertently into the periapical tissues.

Acute periapical periodontitis

This is characterized by an acute inflammatory exudate in the periodontal ligament within the confined space between the root apex and the alveolar bone. Pain is elicited when external pressure is applied to the tooth because the pressure is transmitted through the fluid exudate to the sensory nerve endings. Even light touch may be sufficient to induce pain and, unlike pulpitis, this is generally well located by the patient to a particular tooth due to stimulation of proprioceptive nerve endings in the periodontal ligament. As the fluid is not compressible, the tooth feels elevated in its socket. Hot or cold stimulation of the tooth does not cause pain, as it would in pulpitis. The radiographic appearances are often normal as there is generally insufficient time for bone resorption to occur between the time of injury to the periodontal ligament and the onset of symptoms. If radiological changes are present, they consist of slight widening of the periodontal ligament and the lamina dura around the apex may be less well defined than normal.

The inflammation may be transient if it is due to acute trauma rather than infection and the condition soon resolves. If the irritant persists the inflammation becomes chronic and may be associated with resorption of the surrounding bone. Suppuration may occur if there is severe irritation and tissue necrosis associated with bacterial infection and the continued and massive exudation of neutrophil leucocytes leading to abscess formation. Such an abscess is called an acute periapical or alveolar abscess and, although such abscesses may develop directly from acute apical periodonitis, most arise because of acute exacerbation within a pre-existing periapical granuloma (see below and).

Periapical granuloma with central zone of suppurative inflammation

Chronic periapical periodontitis (periapical or apical granuloma)

Introduction

Persistent irritation, usually derived from bacteria and their products in the pulp chamber and root canals, leads to chronic periapical periodontitis. This is characterized by resorption of the periapical alveolar bone and its replacement by chronically inflamed granulation tissue to form a periapical granuloma. Around the periphery of the lesion the chronic inflammatory stimuli may lead to the formation of dense bundles of collagen fibres that separate the chronically inflamed granulation tissue from the surrounding bone. These collagen fibres, forming a sort of capsule around the lesion, are attached to the root surface and in some cases the granuloma may be removed attached to the extracted toot .

Histologically the lesion consists mainly of granulation tissue infiltrated by lymphocytes, plasma cells, and macrophages and, although the composition of the inflammatory infiltrate varies considerably, T-lymphocytes predominate. Immunological reactions, in response to persistent antigenic stimulation derived from the pulp chamber and root canals, are key factors in the development of the lesion. In addition to the inflammatory infiltrate, deposits of cholesterol and haemosiderin are often present in a periapical granuloma and both are probably derived from the breakdown of extravasated red blood cells. Cholesterol crystals in the granulation tissue are represented in routine histological sections as empty needle-like spaces or clefts, the crystals having dissolved out in the reagents used in section preparation. Multinucleate foreign-body giant cells are grouped around the cholesterol clefts. Foci of lipid-laden macrophages - foam cells - may also be seen . Epithelial cell rests of Malassez incorporated within the granuloma may begin to proliferate, probably as a result of stimulation by growth factors released by a variety of cells within the granuloma. The proliferated squamous epithelium forms anastomosing cords, often arranged in loops or arcades, throughout the granulation tissue. Neutrophil leucocytes in varying stages of degeneration are often seen infiltrating the oedematous intercellular spaces of the epithelium.

Periapical granulomas tend to be asymptomatic, but may be associated with occasional tenderness of the tooth to palpation and percussion. Percussion may produce a dull note because of the lack of resonance caused by the granulation tissue around the apex. Radiological examination at first shows a widening of the periodonal ligament space around the apex and later a definite periapical radiolucency may develop. In some instances this radiolucency is well circumscribed and clearly demarcated from the surrounding bone by a corticated margin, while in others the border is poorly defined. These appearances are related to differences in cellular activity around the margins of the lesion. Where there is active bone resorption and expansion of the lesion the margin is ill-defined. Where the lesion is static and a balance is established between the level of irritation and the host defences, the chronic inflammatory stimulus may lead to bone apposition and the formation of a zone of sclerosis around the lesion (see osteosclerosis (point 5) below). Histological evidence of external resorption of the apical cementum and dentine is frequent and is occasionally sufficient to be detected radiographically.

The importance of the root canal as a continued source of infection and antigenic challenge in an apical granuloma is shown by the fact that most periapical lesions heal once the canal is sealed by satisfactory endodontic treatment. The predominant organisms are obligate anaerobes (70 per cent or more) with smaller numbers of facultative anaerobes. Microorganisms surviving in the root canals or dentinal tubules after endodontic treatment may be important in teeth with persistent apical radiolucencies.

	Periapical granuloma attached to extracted root. 0
	Histological section of root and attached periapical granuloma from.Note the more heavily inflamed central area of the periapical granuloma (blue/purple stained), compared to the less inflamed, more collagenous peripheral zone.   0

	Cholesterol clefts with associated foreign-body giant cells   0
	0

	Periapical granuloma containing proliferating strands of squamous epithelium. 0
	Periapical radiolucency and apical resorption associated with a periapical granuloma. 0

Sequelae

1. If the level of antigenic challenge is in equilibrium with the host's immunological response, the granuloma can remain quiescent for long periods. However, if the equilibrium is disturbed in favour of the microbial flora in the root canal, the granuloma will continue to enlarge and be associated with continued resorption of bone, the process being symptomless, until equilibrium is restored.

2. When organisms invade the granuloma from the root canal acute exacerbation is likely and the patient may present with acute symptoms. Acute exacerbation can cause rapid enlargement of the lesion and may progress to abscess formation (see below). Alternatively, the inflammatory response may overcome the infection and a new equilibrium can be established.

3. Suppuration may occur in the granuloma. This may continue to enlarge to form an acute periapical (alveolar) abscess. Clinically this may present with rapid onset of pain, followed by redness and swelling of the adjacent soft tissues as the abscess tracks and points. The affected tooth is tender to percussion, and there may be slight mobility on palpation. Alternatively, the area of suppuration may be contained by the host's defences to form a chronic abscess that shows little tendency to enlarge or spread and which causes few, if any, clinical signs or symptoms until a further acute exacerbation.

4. Proliferation of the epithelial cell rests of Malassez associated with the inflammation may lead to the development of an inflammatory radicular cyst.

5. Low-grade irritation to the apical tissues may result in bone apposition (osteosclerosis) rather than resorption, histologically a mild chronic inflammatory infiltrate being seen in the rather scanty, fibrous marrow. The process is clinically asymptomatic and shows as an opaque area of bone on radiographs. On occasions, the opacity is well circumscribed while on others it shows no clear line of demarcation from the normal surrounding bone.

6. Low-grade irritation to the apical tissues may also result in the apposition of cementum on the adjacent root surface to produce hypercementosis.

Key points - Periapical granuloma
chronically inflamed granulation tissue around apex of a non-vital tooth
infection and antigenic challenge from endodontic flora
apical radiolucency; margins reflect dynamics of the lesion
host response may be in equilibrium with level of irritation
may be symptomless and remain quiescent for long periods
stimulation and proliferation of rests of Malassez within the lesion

Osteosclerosis around the roots of a mandibular molar.

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Free Download Crown, Bridges and Veneer Wall Chart (Poster)

I needed some wall charts to hand on my clinic. I have searched days and days on internet to find some good posters about "Crowns", "Bridges", and "Veneers". But I couldn't make any. Finally I have decided to make my own posters. I think I have done something very interesting. So I printed them and pasted on the walls of my clinic. After that I thought of uploading them to my blog where everyone can download them. Here are those posters.

Free Download Dental Crown, Bridges and Veneer Wall Chart (Poster)

Dental BRIDGE Wall chart (Poster)

A Bridge is a Dental prosthesis which fills a space that a tooth previously occupied.

Dental CROWN Wall chart (Poster)

Crown is a permenent covering that fits over an original tooth that is earlier decayed, damaged or cracked. 

 

 Dental VENEER Wall chart (Poster)

A Veneer is a thin layer of restorative material placed over a tooth surface, either to improve the aesthetics of a tooth, or to protect a damaged tooth surface. 

 

Hand signs to commiunicate with the dentist during proceedure?

Most of the patients seeking dental treatments might be having a problem of how to communicate with the dentist during the dental procedure. That is because our main source of communication is verble communication which will be affected during dental procedure.
Here are some hand signs which you can use to communicate with the dentist during dental procedure. Please use these hand signals to communicate with the dentist during your dental procedure.

Dear Dentists, You can display this poster in your clinic in the waiting room.

Managing patients who are taking warfarin and undergoing dental treatment

General guidelines

 

• If patients on warfarin who require dental surgery have an International Normalised Ratio (INR) of below 4.0, they can usually receive their dental treatment in primary care without needing to stop their warfarin or adjust their dose.

• The risk of thromboembolism after temporary withdrawal of warfarin therapy outweighs the risk of oral bleeding following dental surgery.

• Patients on warfarin may bleed more than normal, but bleeding is usually controlled with local measures.

Advice to be given to patients

Advice for patients is available in the patient leaflet, Oral Anticoagulant Therapy: Important information for dental patients.

Drug interactions

Amoxicillin

There have been anecdotal reports that amoxicillin interacts with warfarin causing increased prothrombin time and/or bleeding, but documented cases are relatively rare. Patients requiring a course of amoxicillin should be advised to be vigilant for any signs of increased bleeding.

Clindamycin

Clindamycin is restricted to specialist use and should not be used routinely for dental infections due to its serious side effects. There is a single case report of an interaction between warfarin and clindamycin.

Erythromycin and other macrolide antibiotics (for example, azithromycin)

Macrolide antibiotics interact with warfarin unpredictably and only in certain individuals. Patients should be advised to be vigilant for any signs of increased bleeding.

If increased bleeding occurs then the patient should be advised to contact the GP or anticoagulant clinic to arrange additional INR testing and dose review.

Metronidazole

Metronidazole interacts with warfarin and should be avoided if possible. If it cannot be avoided, the warfarin dose may need to be reduced by a third to a half, and re-adjusted again when the antibiotic is discontinued. Contact the GP or anticoagulant clinic to arrange additional INR testing and dose review.

Non-steroidal anti-inflammatory drugs

Drugs including ibuprofen, aspirin and diclofenac should not be used as analgesics in patients taking warfarin.

Dental surgery covered by this advice includes:

Treatment where the INR does not need to be checked:

• Prosthodontics

• Conservation

• Endodontics

Treatment where the INR does need to be checked (follow flow diagram):

• Extractions

• Minor oral surgery

• Periodontal surgery

• Biopsies

Watch-Preparation for Full metal Crown Video

A Apical Diagnosis Flowchart

Apical diagnosis flowchart

Purpose of Root Canal Obturation and method of root canal obturation

Introduction

Root canal obturation involves the three-dimensional filling of the entire root canal system and is a critical step in endodontic therapy. There are two purposes to obturation: the elimination of all avenues of leakage from the oral cavity or the periradicular tissues into the root canal system; and the sealing within the root canal system of any irritants that remain after appropriate shaping and cleaning of the canals, thereby isolating these irritants. Pulpal demise and subsequent periradicular infection result from the presence of microorganisms, microbial toxins and metabolites, and the products of pulp tissue degradation. Failure to eliminate these etiologic factors and to prevent further irritation as a result of continued contamination of the root canal system are the prime reasons for failure of nonsurgical and surgical root canal therapy.

The importance of three-dimensional obturation of the root canal system cannot be overstated, with the ability to achieve this goal primarily dependent on the quality of canal cleaning and shaping as well as clinical skill. Other factors that influence the ultimate success or failure of each case include the materials used and how they are used. The ultimate coronal restoration of the tooth following canal obturation may loom as the most important goal, for there is reasonable evidence that coronal leakage through improperly placed restorations after root canal treatment and failure of the restorative treatment or lack of health of the supporting periodontium are the final determinants of success or failure in treatment.

Factors influencing complete obturation

• Quality of the cleaning and shaping of the canal system
• Skill and experience of the clinician
• Materials and their usage
• Restoration of the tooth
• Health of the supporting periodontium

Characteristics of an Ideal Root Canal Filling

An ideal root canal filling three-dimensionally fills the entire root canal system as close to the cemento-dentinal junction as possible. Minimal amounts of root canal sealers, most of which have been shown to be biocompatible or tolerated by the tissues in their set state, are used in conjunction with the core filling material to establish an adequate seal. Radiographically, the root canal filling should have the appearance of a dense, three-dimensional filling that extends as close as possible to the cemento-dentinal junction. These standards should serve as the benchmark for all clinicians performing root canal therapy, and it is only through a knowledgeable approach to root canal treatment that quality assurance can be continually demonstrated in the obturation of root canal systems.

The ideal root canal filling

3-D filling of the entire root canal space as close as possible to the cemento-dentinal junction

Radiographically dense fill with absence of voids

 

Shape reflecting a continuously tapered funnel that is approximately the same as the external root morphology

While a plethora of materials has been advocated over the last 150 years for root canal obturation, historically, gutta-percha has proven to be the material of choice for successful filling of root canals from their coronal to apical extent. Although it is not the ideal filling material, gutta-percha has satisfied the majority of criteria for an ideal root filling material. The disadvantages of gutta-percha – specifically, its adhesiveness, lack of rigidity, and ease of displacement under pressure – do not overshadow its advantages. In light of its shortcomings, a sealer/cement is always used with gutta-percha. However, regardless of the delivery system or technique used, neither gutta-percha nor sealer/cement alone enables standard-ofcare canal obturation. In addition, the available materials and techniques do not routinely provide for an impervious seal of the canal system; all canals leak to a greater or lesser extent.

It is recommended that clinicians master multiple obturation techniques and become competent with various root canal sealers/cements, to be able to manage the diversity of anatomical scenarios that may be encountered.

Contemporary Sealers/Cements

The use of a sealer during root canal obturation is essential for success. Not only does it enhance the possible attainment of an impervious seal, it also serves as a filler for canal irregularities and minor discrepancies between the root canal wall and core filling material. Sealers are often expressed through lateral or accessory canals and can assist in microbial control should there be microorganisms left on the root canal walls or in the tubules.Sealers can also serve as lubricants, enabling thorough seating of the core filling material during compaction. In canals in which the smear layer has been removed, many sealers demonstrate increased adhesive properties to dentin in addition to flowing into the patent tubules. A good sealer should be biocompatible and well tolerated by the periradicular tissues, and although all sealers exhibit toxicity when freshly mixed, their toxicity is greatly reduced on setting and all are absorbable when exposed to tissues and tissue fluids. Subsequent tissue healing or repair generally appears unaffected by most sealers, provided there are no adverse breakdown products of the sealer over time. In particular, the breakdown products may have an adverse action on the proliferative capability of periradicular cell populations. Some clinicians consider that a small puff of root canal filler extending beyond the working length is indicative of a fully obturated canal space with a well-sealed apical constriction. Excessive sealer should not be routinely placed in the periradicular tissues as part of an obturation technique.

Sealers/cements can be grouped based on their prime constituent or structure, such as zinc oxide-eugenol, polyketone, epoxy, calcium hydroxide, silicone, resin, glass ionomer, or resin-modified glass ionomer. However, many of the sealers/ cements are combinations of components, such as zinc oxideeugenol and calcium hydroxide,43 with the addition of calcium hydroxide claimed to create a therapeutic material that can be inductive of hard tissue formation.Epoxy-based and methacrylate-based resin sealers that can be bonded to the root canal dentin (but not to gutta-percha) are also now available.

Sealers should be mixed to a creamy consistency, allowing them to adhere to the master cone and not ball up at the shaft of the cone, leaving the gutta-percha exposed. The sealer should adhere to the cone evenly along its length and at the end of the cone. Clinicians should read the product insert and material safety data sheet for each product chosen before using it.

Contemporary Core Filling Materials

Gutta-percha is the standard material of choice as a solid core filling material for canal obturation. It demonstrates minimal toxicity and minimal tissue irritability, is the least allergenic material available when retained within the canal system,and in cases of inadvertent gutta-percha cone overextension into the periradicular tissues, is well tolerated provided the canal is clean and sealed. Chemical solvents have been used for almost 100 years to soften gutta-percha, with methods ranging from merely dipping the gutta-percha cones into the solvent for one second for better canal adaptation, to creating a completely softened paste of gutta-percha with the solvent. Solvents used have included chloroform, halothane, rectified white turpentine, and eucalyptol. Periradicular tissues may be irritated if the solvent is expressed beyond the canal or significant amounts of softened gutta-percha are inadvertently placed into the periradicular tissues. Failure to allow for dissipation of chemical solvents, if volatile, or the removal of excess solvent with alcohol can result in significant shrinkage and possible loss of the apical seal. The use of chemical solvents has been both praised and questioned, but with the advent of thermoplasticized gutta-percha, the need to consider the use of solvents at any time must be questioned. The use of solvents, however, may still be considered for a number of challenges the clinician may face in daily practice, such as the custom fitting of master cones in irregular apical preparations or following apexification.

Gutta-percha Cones

The composition of gutta-percha cones is approximately 19% to 22% Balata and 59% to 75% zinc oxide, with the remainder a combination of various waxes, coloring agents, antioxidants, and metallic salts.58 The specific percentages for components varies by manufacturer, with resulting variations in the brittleness, stiffness, tensile strength, and radiopacity of the individual cones attributable primarily to the percentages of gutta-percha and zinc oxide. The antimicrobial activity of gutta-percha is also primarily due to the zinc oxide.

The cones are manufactured in both standardized and nonstandardized sizes. The standardized sizes coordinate with the ISO root canal files sizes 15 through 140 and are used primarily as the main core material for obturation. They generally have a 2% taper, but can have a 4 or 6% taper or more. The non-standardized sizes are more tapered from the tip or point to the top. With some obturation techniques these cones have been used primarily as accessory or auxiliary cones during compaction, being matched with the shape of the prepared canal space or the compaction instrument.

Non-standardized cones began to assume a greater role as the primary core material in the more contemporary obturation techniques, and with the development of more predictable shapes with current nickel titanium (NiTi) rotary and hand instruments, cones tapered from 4% to 10% have gained use.

Tapered gutta-percha cones

In particular, for techniques that use vertical compaction of heat-softened gutta-percha, both the non-standardized and more tapered cones have become quite acceptable. Custom cones can also be developed for canals with irregular or large apical anatomy, Over time, numerous methods have been advocated for obturating the prepared root canal system, each with their own claims of ease, efficiency, or superiority. Most contemporary techniques still rely on gutta-percha and sealer to achieve their goal. Four basic techniques exist for the obturation of the root canal system with gutta-percha and sealer

(1) the cold compaction of gutta-percha; (2) the compaction of heat-softened gutta-percha with cold instruments

Cold compaction carrier              Heated compaction              Presoftened core

until it has cooled; (3) the compaction of gutta-percha that has been thermoplasticized, injected into the system, and compacted with cold instruments; and (4) the compaction of gutta-percha that has been placed in the canal and softened through the continuous wave technique (Calamus). A multitude of variations on these four basic themes exists. For injectable thermoplastic obturation techniques, gutta-percha may come in either pellet forms or in cannulae.

Cold compaction carrier Heated compaction Presoftened core

No single technique has proven to have statistically significant superiority when considering both in vitro and in vivo studies, as the success of all techniques is highly dependent on the cleaning and shaping of the canals and the clinician’s expertise in the use of a particular technique.While many have advocated the use of the lateral compaction technique or a single cone fill (monocone) to achieve a quality apical seal, the technique in itself does not necessarily favor the filling of canal irregularities.63 Recognizing this, use of a softened gutta-percha technique with heat or chemical softening is required to achieve a thorough obturation.

In addition, while filling the entire root canal system is the major goal of canal obturation, a major controversy exists as to what constitutes the apical termination of the root canal filling material. Working length determination guidelines often cite the cemento-dentinal junction or apical constriction as the ideal position for terminating canal cleaning and shaping procedures and placing the filling material. However, the cemento-dentinal junction is a histologic and not a clinical position in the root canal system and, in addition, the cemento-dentinal junction is not always the most constricted portion of the canal (yellow arrows) in the apical portion of the root

Contemporary practices of obturation favor material softening even this does not guarantee that an impervious seal of the root canal system will be established. Also, with softened gutta-percha obturation techniques there has been a greater incidence of material extrusion beyond the confines of the canal. While softening of gutta-percha may be viewed as routinely desirable, the selective use of this technique solely or in combination with a solid core of gutta-percha must be at the discretion of the competent clinician when anatomy dictates this approach.

Apical constriction of root canal

Recent research conducted at Nova Southeast University using micro CT scanning technology has shown the effectiveness of scanning for imagery and the greater precision observed compared to standard radiographs. In one example, a mesiobuccal canal was filled using GT® Series X™ obturator and the mesiolingual canal was filled using a single cone technique (ActiV GP). It appeared from one angle that all canals were equally filled.

Radiograph of filled canals

However, closer examination subsequent to filling showed voids using the single cone technique throughout the length of the root filled using this technique. The single cone technique did not produce a monoblock obturation. The gutta-percha from the GT obturator flowed into the canal isthmus and filled it.

Voids using single cone technique

Cross-section with ActiV GP and GT Series X obturation

                                          

                                Activ V GP             GT Series X obturator

Canal isthmus filled with GT obturator gutta-percha

Differences in obturation techniques and results are also more observable using CT scanning than using traditional radiographs.Contemporary techniques include the use of bonded root canal filling materials. Recent developments in resin-bonding have led to the availability of resin cones and pellets similar in shape and size to gutta-percha materials.

Resin-based cones containing methacrylate resin, fillers, bioactive glass, and polymers are available that can be handled similarly to gutta-percha and can be used with a lateral or vertical compaction technique. Resin-based materials can also be delivered via a heated syringe (Obtura gun, Spartan Obtura). Since resin-based materials require a slightly moist environment, it is important to avoid using any dessicating solutions, such as alcohol, during root canal preparation. Further, if sodium hypochlorite or peroxide was used during root canal preparation, this must be thoroughly removed prior to using a resin-based material as it would reduce the ability of the resin material to bond. Similarly, the smear layer must also be thoroughly removed.

Prefabricated Obturators

Gutta-percha can also be formed on a plastic carrier or corecarrier. Prefabricated obturators were first described in 1978 by William Ben Johnson.79 The prototype for the obturator had been prenotched K-files wrapped in gutta-percha (hand formed) that were then heated over a flame until the surface glistened and expanded. These prenotched “obturators” were inserted into the canal and apical pressure applied while the handle was twisted off.

Prototype obturator

Prefabricated obturators were introduced in 1988 (Thermafil) using first a stainless steel and subsequently a titanium core, coated with gutta-percha. Plastic obturators were first offered in 1992. Since then, a number of prefabricated obturator systems have been introduced, including one that does not involve thermosoftening of the gutta-percha (SimpliFil, Discus Dental) but instead is used cold with only the apical area coated in gutta-percha, and after placement the carrier itself is removed.

A recently developed prefabricated obturator utilizes a resin-based system (RealSeal One, Sybron Endo) and is used with, and bonded to, methacrylate resin-based sealer material and is first held in its custom oven and thermosoftened. Other systems use thermosoftened gutta-percha, including Calamus® (Tulsa Dental, Dentsply) , Successfil® (Hygienic-Coltene-Whaledent, Inc.), Gutta- Flow®, System B Obturation System, Thermafil, Thermafil Plus, ProTaper® Universal and ProSystem GT® Obturators (Dentsply, Tulsa Dental), and Soft-Core® (Soft-Core® Texas, Inc.).

Current plastic obturators are available in a nonvented shape with a taper of around 0.04 (Densfil) and a vented shape with the same taper (Thermafil Plus). Both are biologically inert. The carrier is thick with a thinner outer coating of gutta-percha, which helps to reduce material shrinkage as the gutta-percha cools in the canal. A vented prefabricated obturator helps the flow of gutta-percha during placement and also aids in retrieval of the obturator should retreatment be necessary.

For sizes 40 and below in the Thermafil series, an insoluble liquid crystal plastic is used. For size 45 and above soluble polysulfone polymer is used. All of these use a size verifier to help select the correct size obturator, as do ProTaper Universal carriers, which start at a .04 taper. Systems that do not use a size verifier include the ProSystem GT carriers and GT Series X carriers, which are made in a variety of tapers between 0.04 and 0.12.