General Updates, Study Guides

Are Most Published Research Findings False?

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Slimey DelightAlong with some other enlightening speakers, I just had the pleasure of listening to a full day of lecture material by Dr John Ioannidis. Dr Ioannidis is a leader in the field of Epidemiology and Research Statistics. In 2005 he authored an article entitled, “Why Most Published Research Findings are False”.

I’ve read his articles before, but having the man himself run through each of the areas covered in the article was a real eye opener. I don’t want to be critical of all the dedicated and hard-working researchers out there. We owe them a debt of gratitude. But, it would seem that the publishing of research findings is a an area where accidental (or non-accidental) misleading statement, conclusions and assumptions are often made.

The biggest issue we have is the pursuit of findings that are often based on research with a formal statistical significance, commonly with a p value less than 0.05. Dr Ioannidis shows that these findings can often be incorrect. He should know. He’s been involved in large scale studies which made findings that were later refuted and shown to be (more than likely) incorrect.

As practitioners, we are called upon ever day to make decisions based on the published research, so it is important that we have a good understanding of what we are reading. I recommend reading the article by Dr Ioannidis and taking note of the corollaries he mentions. It is this sort of introspection which makes us better practitioners.

Please, read his article. In fact, don’t read it, study it, and get interested in what all those statistics actually mean.

John Baez does a nice job of simplifying the corollaries, and there is some good discussion to follow it on his blog.

The article is free here: http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0020124

Clinical Tips, Diagnosis of Pulpal Pathology, Endodontic Radiography

Perio-Endo? Get Some GP in it!

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The second most common reason for extraction of root filled teeth is periodontal disease. So it’s important we identify periodontal disease when deciding if we should treat a tooth. Periodontal pockets around teeth can generally be due to three things:

1. Periodontal disease;

2. Vertical root fracture;

3. A sinus tract draining through the PDL.

Usually, a true periodontal pocket will be broad, whereas a pocket due to a root fracture or a draining sinus will be very narrow. We are more likely to find a true periodontal pocket in a patient who suffers periodontal disease in other teeth besides the one we are looking at.

When we do identify a periodontal pocket in a tooth that also has apical periodontitis, we want to know if the periodontal disease is separate to the apical disease. When these two are combined in a perio/endo lesion, the success rate in treating the teeth is lower than when we have separate perio and endo disease. If the pocket is narrow, then it’s important to differentiate between the draining sinus (which may be easy to treat) and the root fracture, which cannot be treated. I usually do this by raising a flap and inspecting the root with the microscope after staining with methylene blue.

Endo Perio lesion

GP placed into a sinus tract helps determine the true depth of the sinus tract.

In cases where I find a very deep, broad periodontal pocket which I think may be to the apex of the tooth, I place a GP point in the pocket to full length and take a radiograph. If the GP extends to the apex, then I know we have a fight on our hands to save the tooth.

The Endospot

A true perio/endo lesion makes this tooth a difficult prospect for successful treatment.

In the comments section, please leave your tips on identifying perio/endo lesions.

Diagnosis of Pulpal Pathology, Microbiology

How Strong Can A Pulp Be?

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Way back in 1965 Kakaehashi et al(1) showed us that in the absence of microorganisms, even exposed dental pulps can survive quite well. For those of you who aren’t familiar with the research, gnotobiotic (or germ-free) rats had pulps exposed and the access cavities were left completely open. These rats lived in a sterile environment and ate sterile food. After the rats were sacrificed, histology showed that even though the pulp exposures were open and had food and debris packed into them, the pulps in these teeth remained vital and showed healing in the form of dentine bridging. Conversely, the rats who lived in normal environments showed bacterial contamination of their pulps leading to necrosis and paeriapical inflammation.

Vital Pulp Post Endodontic

This tooth had been asymptomatic for forty years, despite having no root filling present.

I recently treated a case where a single piece gold inlay and post needed to be removed as there was carious breakdown of the margins. The tooth was asymptomatic and had been so since the post and restoration was placed over forty years prior. There was no root filling to be seen .On removal of the post and restoration, I was a little surprised by what I found. Have a look at the video below…..

httpv://www.youtube.com/watch?v=1bgUq588xPc

The apical portion of the pulp remained vital after 40 years. This shows the importance that microorganisms play in pathology of the pulp. Other factors, especially heat from preparations (especially when not using water spray) and mechanical trauma can damage a pulp, but microorganisms play the MOST important role.

So, my recommendations when placing restorations are to use chlorhexidine or sodium hypochloride to clean cavities prior to restoration, use a good aseptic technique to exclude saliva (i.e. rubber dam) and use materials and techniques that seal well and prevent bacteria gaining access to deeper parts of restorations and thus the pulp. Oh, and don’t try putting a post into tooth without root filling it first. You’re not going to get as lucky as the dentist who did this one.

Endodontics, endospot

Final Obturation with post space left in tooth 21.

 

References:

1. The Effects of Surgical Exposures of Dental Pulps in Germ-Free and Conventional Laboratory Rats. KAKEHASHI S, STANLEY HR, FITZGERALD RJ. Oral Surg Oral Med Oral Pathol. 1965 Sep;20:340-9.

Diagnosis of Pulpal Pathology, Study Guides

Classifying Cracked Teeth. Operation Complex Part II

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CRACKED TEETH: Classification

Cracked teeth can be one of the most complex, confusing and frustrating dental problems we face in every day practice. Its estimated in general practice that at least one patient per week presents with symptoms relating to a cracked or fractured tooth.  Accurate diagnosis and correct management are obviously the crucial steps of successful treatment, but we need to start by defining the various crack types to ensure we are all talking about the same thing at the same time.

It is important for us to have a clear understanding of what is meant by each definition as this allows discussion of the characteristics, prognosis and reliable treatment planning for each crack type. There are many classification systems out there for cracked teeth. Thankfully, the American Association of Endodontists (AAE) has developed a simple classification system for longitudinal tooth fractures based upon their location, direction, and extent. Not everyone out there agrees with this classification, but it’s the best we have and a good starting point when trying to manage.

Craze Lines
Craze lines occur only within enamel. They run parallel to enamel rods and terminate at the DEJ (Bodecker et al. 1951). Craze lines are present in most adult teeth. Various patterns of infraction lines can be seen depending on the direction and location of the impact to enamel, i.e. horizontal, vertical or diverging. Anterior teeth often exhibit vertical craze lines, involving the incisal edge or proximal corners. Posteriorly, craze lines usually cross the marginal ridges and extend along buccal and lingual surfaces.

Fractured Cusp
Fractured cusps occur most frequently in heavily restored teeth, where the marginal ridge is weakened and the affected cusp has insufficient support (Kahler 2008). A fractured cusp involves a complete or incomplete fracture initiated from the crown and extending subgingivally, usually directed both mesiodistally and buccolingually (Rivera & Walton 2008). The fracture usually crosses the marginal ridge, and also tracks down a buccal or lingual groove. It extends to the cervical third of the crown or root.

Cracked Tooth

Fractured Cusp

Cracked Tooth
A cracked tooth is an incomplete longitudinal fracture originating in the crown and extending apically. Often cited as being only in a mesio-distal direction (Rivera & Walton 2008), the literature also reports an significant number of bucco-lingual fracture planes (Seo et al. 2012). It may extend through either or both of the marginal ridges, through the proximal surfaces and onto the root surface. Occlusally, the crack is more centred and apical than a fractured cusp and therefore more likely to cause pulpal and periapical pathosis (Rivera & Walton 2008). A cracked tooth may progress to a split tooth.

Cracked Tooth

Cracked Tooth

Split Tooth
A split tooth is a complete fracture originating in the crown and extending subgingivally, directed most commonly mesiodistally through both marginal ridges and proximal surfaces (Seo et al. 2012). The split root area is often in the middle or apical third and tends towards the lingual. The more centred the crack is on the occlusion, the further apically the split extends. The segments are entirely separate and although it may occur suddenly it may be considered as a continuum from an incompletely cracked tooth (Rivera & Walton 2008).

Split Tooth

Split Tooth

Vertical Root Fracture
Vertical root fractures are complete or incomplete fractures initiated from the root (at any level), usually directed buccolingually (Rivera & Walton 2008). Most occur in endodontically-treated teeth although the literature reports occurrences in non-root filled teeth (Yang et al 1995). A VRF may progress coronally and/or apically from the point of origin in any part of the root.

Vertical Root Fracture

Vertical Root Fracture

Now we’re all on the same page, take a look at the next post in this series: Management of Cracked Teeth for an overview of recommended treatment strategies.

REFERENCES
Bodecker, CF, Gottlieb, B, Orban, B, Robinson, HB, Schour, I,  Sognnaes, RF 1951. Enamel lamellae. Oral Surg Oral Med Oral Pathol, vol. 4, 787-98.
Kahler, W 2008. The cracked tooth conundrum: terminology, classification, diagnosis, and management. American Journal of Dentistry, vol. 21, 275-82.
Rivera, EM,  Walton, RE 2008. Cracking the Cracked Tooth Code: Detection and Treatment of Various Longitudinal Tooth Fractures. Endodontics Colleagues for Excellence, Summer 2008.
Seo DG, Yi YA, Shin SJ, Park JW (2012) Analysis of factors associated with cracked teeth. Journal of Endodontics 38(3), 288-292.
Yang SF, Rivera EM, Walton RE (1995) Vertical root fracture in nonendodontically treated teeth. Journal of Endodontics 21(6), 337-339.

Conservation of tooth structure
Clinical Tips, Endodontic Preparation Techniques, General Updates

Endodontic Access for Conservationists. A How To Guide.

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There are a huge number of factors that can affect the outcome of endodontic therapy. Attempting to isolate these individual factors and determine the relative importance of each is something that has proven difficult or impossible in endodontic scientific literature.

Ultimately, our primary aim is to allow our patients to keep their teeth for the rest of their lives. The evidence we have available points to the majority of endodontically treated teeth surviving for long periods of time. (1) Those that are extracted most commonly fail due to non-endodontic reasons. The most common cause of extraction of root filled teeth is crown fracture and periodontal disease.(2)

In terms of crown (and root) fracture, I believe that the conservation of dentine in the crown and in the region a couple of mm just above and below the cervical area is essential to providing ongoing resistance to fracture. In order to have as strong a tooth as possible, we need maximum thickness of tooth structure in this area.

In terms of this, I see that using strategies to limit the amount of tooth structure loss during endodontic access as one of the most important measures that can be taken to ensure the greatest longevity for root filled teeth. Of course, we still need to achieve the aims of endodontic treatment, but this shouldn’t come at the cost of doing irreversible damage to the crown of the tooth that may compromise the tooth’s long term survival.

Poor endodontic access

Endodontic access has been performed which gives good access to the canal orifices. But imagine the thickness of dentine that will remain mesially and distally if a crown was prepared for this tooth. The endodontics can be perfectly performed, but the tooth is compromised due to the excessive loss of tooth structure during access.

This is why we aim to keep access limited and you will sometimes see what appears to be incomplete opening of the pulp chamber. This is by design and allows important tooth structure to be maintained that contributes to the strength and durability of the tooth. Strategies for conserving tooth structure during endodontic access include removing restorations and caries and utilising this space for endodontic access. A good discussion of these strategies, along with examples can be found in articles by Clark and Khademi. (3) (4)

Conservative endodontic access in lower molar

Maintaining the dentine in the peri-cervical region whilst achieving the goals of endodontics give this tooth the best possible chance of survival. Ultrasonics and copious irrigation allow the cleaning of the pulp chamber space and canal spaces without the need for excessive removal of tooth structure.

Maintaining dentine for endodontic access

The restricted access still give good straight line access to the canal orifices. But see how much solid tooth structure remains? It does, however make the job of performing high quality endodontics more difficult. But what’s more important? Us having an easy time of it, or giving the patient the best possible long term outcome?

Limiting tooth destruction becomes a greater challenge when attempting to treat teeth with calcified pulp chambers or canals. When attempting to work through pulp chamber calcification or locate these difficult to find canals it can be easy to remove vitally important dentine.  Assessing the degree of calcification prior to attempting treatment is the key to preventing this iatrogenic damage to teeth. Additionally, if upon access the location of all canals is difficult, it may be better to consider referring at that early stage, rather than to damage the tooth’s long term prognosis in an attempt to locate a difficult to find and prepare canal.

One important aspect of learning to limit the removal of healthy tooth structure for access is that it actually makes endodontic procedures much more difficult (especially in second and third molars) and increases the chances of missing canals, so you need to balance these potential issues with benefits of doing so.

1.    Salehrabi R, Rotstein I. Endodontic treatment outcomes in a large patient population in the USA: An epidemiological study. J Endod. 2004;30(12):846-50.
2.    Vire D. Failure of endodontically treated teeth: classification and evaluation. J Endod. 1991;17:338-42.
3.    Clark D, Khademi J. Modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010 Apr;54(2):249-73.
4.    Clark D, Khademi JA. Case studies in modern molar endodontic access and directed dentin conservation. Dent Clin North Am. 2010 Apr;54(2):275-89.

Aetiology of Apical Periodontitis, Clinical Tips, Diagnosis of Pulpal Pathology

Viral Pulpitis. This Would Have to Hurt…..

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We usually blame bacteria for causing pulpitis but………. This patient complained of severe irreversible pulpitis symptoms for four days, which were only just starting to settle. She couldn’t isolate to either the upper second premolar or molar. Her dentist had extirpated the molar but symptoms hadn’t changed. Pulp testing showed the premolar was also responding negatively.

Take a look at the image below. This presentation is consistent with herpes zoster, commonly referred to as shingles. It is caused by the varicella zoster virus, also responsible for chicken pox. The trigeminal nerve is an unusual location for an outbreak (approximately 1-2% of cases), but when it occurs the virus affects a particular dermatome. If this dermatome also includes teeth, the pulp can also be affected. I can only imagine how painful this would be. Long term follow up is required as multiple teeth may lose vitality.

Notice how the viral outbreak is only affecting the greater palatine nerve distribution. If the nerve innervating the teeth are involved, this can lead to pulpitis and necrosis of the pulp tissues.

Diagnosing this initially may prove difficult, as the lesions on the mucosa don’t show up until a few days after symptoms appear, but some things to look out for include pulpitis symptoms from multiple teeth and a tingling or burning sensation in the distribution of the trigeminal nerve.

Pat Caldwell

General Updates

Diagnosing Cracked Teeth. Operation Complex.

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In Australia, the average dentist sees at least one patient with cracked tooth syndrome (CTS) per week (Bader et al 1995), so managing this condition is bread and butter work.  When dealing with CTS a good outcome relies on an accurate diagnosis but this can vary from straightforward diagnostic results to complex, inconsistent signs and symptoms that are difficult to distinguish from other dental and non-dental pathologies.

A detailed pain history is a good place to start. First and foremost, look out for pain on biting. Sensitivity to cold/sweet/hot, and symptoms of reversible/irreversible pulpitis may be reported too. Where there is periodontal involvement due to advanced CTS or vertical root fracture, there may also be recurrent swelling, or a feeling of vague pain or pressure. Patients with a cracked tooth often report having made multiple dental visits, with only temporary pain relief achieved.

I think it’s important to distinguish between what we refer to as CTS, and vertical root fracture. CTS usually occurs in a vital tooth. The pain that is felt is a response of the vital pulp and progression of the condition relates to increasing inflammation of the pulp due to bacterial infiltration of the crack. Vertical root fracture occurs most commonly (but not exclusively) in root filled teeth. The pain that is felt is periodontal in nature and relates to infection of the crack.

When it comes to conducting the examination, we’re looking to confirm first the diagnosis of CTS, and secondly diagnose the pulp. These include, in order of importance:

  • Bite tests to reproduce the chief complaint. By far the best method is to use a ‘Tooth Slooth’ or ‘FracFinder’. Cotton rolls, rubber wheels etc. can be used, but they can’t as accurately isolate pressure to one part of the tooth.

Note: Though pain on release is considered to be a classic sign of a cracked cusp, one study actually found that 68% of cracked tooth cases had pain only when pressure was applied (Abbott & Leow 2009). That said, if you do find that the pain is significantly worse on release than on biting, you can be comfortable with the diagnosis of CTS.

  • Perio probing – presence of a deep, narrow pocket at a single site may indicate a vertical root fracture or endo lesion draining through the periodontium.

In this xray you can see the two molars present with lucencies that surround the coronal portion of the mesial roots. The video below is not the best quality, but you get the drift of how a vertical root fracture presents. A vertical root fracture usually presents as a deep, narrow pocket. Locating a pocket such as this can only be done adequately under local anaesthesia.

Note the lucency surrounding the mesial roots of the first and second molars, yet there is no distinct periapical lucency. This is suggestive or vertical root fracture. The video below shows the periodontal probing pattern.

httpv://youtu.be/8P5trYcaNII

  • Visual examination (with dental operating microscope and rubber dam for best results). Pay particular attention to marginal ridge areas. Restoration removal is ESSENTIAL to visualise the crack completely.
Diagnosis of Cracked Tooth

Removal of the restoration allows the full extent of the crack to be visualised.

  • Staining and/or transillumination – staining the crack with methylene blue + transillumination is a good combination to confirm the presence of a crack. (Wright et al. 2004).
  • Pulp testing – The pulp is usually vital in CTS and non-vital in vertical root fracture, but you need to confirm this, because the status of the pulp will help determine treatment.
  • Palpation, percussion testing, mobility testing as per ususal to confirm pulpal and periapical status.
  • Radiographic examination – may not be useful in actually identifying the crack, but it can help to rule out other options during your differential diagnosis stage. In cases of complete vertical root fracture, you may be able to see periradicular bone loss (a ‘halo’ radiolucency). There is plenty of debate as to whether CBCT can confirm the presence of a crack, and I would be wary of relying on this for diagnosis.

I’ll discuss my preferred method of management of CTS in an upcoming post.

References

Abbott, P,  Leow, N 2009. Predictable management of cracked teeth with reversible pulpitis. Aust Dent J, 54, 306-15.

Bader, JD, Martin, JA,  Shugars, DA 1995. Preliminary estimates of the incidence and consequences of tooth fracture. J Am Dent Assoc, 126, 1650-4.

Wright, HM, Jr., Loushine, RJ, Weller, RN, Kimbrough, WF, Waller, J,  Pashley, DH 2004. Identification of resected root-end dentinal cracks: a comparative study of transillumination and dyes. J Endod, 30, 712-5.

Clinical Tips, General Updates, Study Guides

An Endodontic Masterclass

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This is just a short post to let you know that I will be running a hands-on course for general dentists on October 12 in Brisbane. I wanted to let Endospot followers have the first opportunity to sign up. It should be a great day with a nice mix of useful information, practical advice and hands-on experience.

You can download the course flyer here or sign up here.

I hope to see you there.

Pat Caldwell

Clinical Tips, Endodontic Preparation Techniques, General Updates, Irrigation

The Squid. A Study in Persistence and Access Design

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I know it’s been a long time since I’ve posted so I thought I’d show a case that caused me some trouble recently. The owner of this tooth had suffered a significant facial swelling and ended up in hospital. Fortunately, the swelling had subsided by the time I saw him and he was keen to save the tooth.

Lower Premolar with unusual anatomy

A Wide Canal That Narrows Suddenly is an Indication of a Splitting Canal.

Lower premolar AP 2
Apical Periodontitis is Apparent. Note the Bulbous Shape of The Root.

The thing to note about this pre-op xray are that the canal appears to split at the mid root level. Even if you can’t see the split, the fact that the canal narrows suddenly is an indication of a split in the canal system. The second telling point that we are dealing with something complex is the bulbous shape of the root, when compared to the first premolar. This alone would tell us that we should be looking for anatomy other than a single canal.

I was able to locate two canals, and confirm that these canals joined apically, but I wasn’t happy with the position of the files in the radiograph. As you can see, the lingual canal was quite centred in the root, while the distobuccal canal is shifted to the distal. It doesn’t look right does it? There must be another canal.

Lower Premolar with unusual anatomy showing working length

Note the Off-Centre Location of the Second File

So…. I know to look for a third canal, but no matter how hard I looked, I just couldn’t find it. The canal were prepared and obturated, with the result below.

Initial Obturation Unusual Premolar

After Preparation and Obturation a Small Squirt of Sealer to the Mesial Confirms the Missed Anataomy

So you can see the squirt of sealer to the mesial at the mid-root point. There is no doubt that some anatomy has not been properly cleaned, and would likely be full of infected tissue. Back in we go. The GP was removed and the access expanded to allow location of the canal to be identified and confirmed with a file.

Unusual Anatomy in Premolar

There it is!

The third canal was then prepared. It too joined the other canals apically. The key to cleaning this sort of anatomy is passive ultrasonic irrigation, which I have discussed previously. The only way to then obturate is with a warm technique such as continuous wave or warm vertical. The tooth, of course needs a crown. In this case persistance paid off and the outcome can be much more certain now that the full anatomy has been cleaned and obturated. In hindsight, a cone beam CT scan may have assisted in locating the full anatomy.

Pat

Premolar with unusual anatomy

I Call This Tooth “The Squid”

Unusual Anatomy of Premolar After Obturation

The Arrow Shows the Spot Where the Missing Canal Was Located