Problem-solving endodontics: length estimation in a case of hypercementosis

hypercementosisJohn Rhodes presents an interactive practical and problem solving solution in endodontics. This month, he looks at how to overcome difficulties estimating root length in a case of hypercementosis.

Hypercementosis is idiopathic but has been associated with local and systemic factors such as over-eruption of teeth, inflammation at the apex of a tooth, traumatic occlusion and Paget’s disease.

It is a non-neoplastic condition characterised by the excessive build-up of normal cementum on the roots of one or more teeth. The thicker layer of cementum makes the root tip appear larger and it can be difficult to identify the apex on a paralleling radiograph.

Teeth with hypercementosis do not require root canal treatment unless associated with pulpal or periapical inflammation. The altered radiographic morphology can make treatment and in particular length estimation more complex.

Figure 1

Figure 1: Radiograph shows hypercementosis associated with the LR5 and LR6

A paralleling radiograph shows hypercementosis associated with the LR5 and LR6.

There is a periapical radiolucency LR6. The roots of this tooth are long with bulbous tips and the root canals sclerosed. The pulp has reacted to the large amalgam restoration and associated potential microleakage; there is irritation dentine in the pulp where the filling is at its deepest.

The pulp horns are highest mesially and this is where access cavity preparation will be initiated. Root filling material in the LR5 is short of the apex but there are no radiographic signs of apical pathology.

Figure 2

Figure 2: Small volume CBCT clearly demonstrates the hypercementosis

Small volume CBCT clearly demonstrates the hypercementosis. Four main canals can be identified and they have acute curvature in a buccal-lingual direction (something that cannot be appreciated on a radiograph). The LR5 is not associated with any periapical pathology.


After achieving profound anaesthesia and fitting rubber dam, access cavity preparation was started.

In this case I felt that the amalgam restoration was good and decided to make access through it. Initial penetration into the highest part of the mesial pulp horn was made with a long tapered diamond bur.

Once this had been achieved the pulp chamber roof was lifted off and the lateral borders of the access defined using an Endo-Z non-end cutting tungsten carbide bur (Dentsply Sirona).

Coronal flare

The coronal third of the root canals were enlarged using a Protaper SX (Dentsply Sirona) rotary instrument, brushing in to the bulkiest wall of the root and on the outer curve in a buccal-lingual direction.

After irrigation with 3% sodium hypochlorite root length was estimated using an apex locator.

Apex locators

Figure 3: The diagnostic working length radiograph shows the correct root lengths and confluence apically

Apex locators are a very accurate way of determining the root length and generally better than a diagnostic working length radiograph since the apex can be up to 4mm from the radiographic terminus and this can be difficult to determine when the cortical plate is thick.

There are a few points to bear in mind when using an apex locator to get the best results and prevent false readings:

  • Make sure the unit has good battery levels or is fully charged
  • Metal restorations do not need to be removed you just have to make sure that the file does not touch them when using the apex locator
  • Make sure that the pulp floor is dry, sodium hypochlorite will conduct electricity and may allow short-circuiting
  • The canals do not need to be dry, some moisture can be beneficial
  • Use a file that is ‘snug’ in the root canal
  • Always work to the zero reading
  • Compare your reading with the pre-operative radiograph, your knowledge of anatomy. If there is any discrepancy consider an adjunctive radiograph
  • Short readings may indicate a perforation.

Root length estimation

Figures 4 and 5: Two radiographs from different angle demonstrate the completed root canal filling. An excellent coronal apical seal has been achieved and length control is good

In this case the canals were sclerosed and had significant curvature in the buccal-lingual plane.

Sizes 8 and 10 would not advance to the full working length so I used a size 6 with watch-winding action until it reached the zero reading. A glide path was then created with the 8 and 10 files using small increment filing action and watch-winding.

To see how these steps are applied visit:

Tapering the canals

Once a reproducible glide path had been established with a size 10 hand file it was safe to rapidly taper the primary root canals with rotary or reciprocating instruments.

In this case tapering was carried out with Small and Primary Waveone Gold (Dentsply Sirona) instruments. The canals were prepared to approximately two thirds of the length in one pass and completed in a second or third. Patency was confirmed with an ISO size 010 file and the canals irrigated profusely.

The canals had significant curvature in the buccal-lingual plane and so recapitulation was important to make sure that they remained patent. I confirmed the working lengths with the apex locator and exposed a diagnostic working length radiograph after preparation with the Primary Waveone Gold instrument to be absolutely confident (Figure 3).


The root canals were irrigated using 3% sodium hypochlorite. They were agitated with an endo-activator (Dentsply Sirona) in a pumping action (Figure 3). Master Gutta Percha cones were measured and a trial fit carried out while the canals were filled with irrigant.


The root canal system was obturated using a vertically compacted Gutta Percha technique and AH Plus sealer (Dentsply Sirona).

Coronal seal

The access was sealed with IRM packed in to the coronal aspect of the root canals and Fuji IX compomer.

The case will be reviewed at six months to confirm bony healing apically. The general dentist will provide a full-coverage crown to prevent fracture (Figures 4 and 5).

Watch the video

To see how these steps are applied visit: or search Youtube for Endodontic Practice – Retreatment of UL1 with apical resorption or johnrhodesendo.

The author is happy to answer questions directly via Youtube or Twitter @johnrhodesendo.

This article first appeared in Endodontic Practice today.

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