Front tooth implant after a root fracture — same-day extraction, bone graft & implant (#11)

The patient, a man in his 60s, had an upper front tooth (upper right central incisor, #11) that had been crowned more than 30 years earlier. While eating, the tooth suddenly felt as if it had shifted, and he came to RODIN.

Even when a front tooth looks almost unchanged, a crown that feels loose or moves when you bite can be a sign of a problem in the root underneath it.

At the first examination, the tooth was not loose, but the pocket on the front (labial) side measured 7 mm and bled on probing. A deep pocket confined to one spot on a single tooth, while the surrounding gum is otherwise shallower, can be a sign of a root fracture, as bacteria travel down along the crack.

A 3D CT scan (cone-beam CT) showed that the root of the tooth had fractured, and that the bone on the front (labial) side of the root had resorbed. A root fracture line can be hard to see on a conventional two-dimensional X-ray, so a 3D scan is useful for this diagnosis.

A root fracture is a crack or split in the part of the tooth that sits inside the gum and bone. A fracture can run along the length of the root (a vertical root fracture) or across it (a horizontal root fracture).

Once a crack reaches the root, bacteria can enter along the fracture line and the bone around the root can gradually break down. Symptoms may be mild at first, so bone loss can progress before the patient notices. In this case, the labial bone had already resorbed.

Depending on how and where the root has split, an attempt to keep the tooth (for example by bonding) is sometimes possible. When the crack is deep and the surrounding bone has been lost, extraction is usually the recommended option.

In this case, the extracted tooth showed a crack in the root beneath the crown (photo).

During root canal treatment, decay and the inside of the tooth are cleaned out, so less tooth structure remains. A post and core are often placed before a crown, and biting forces can concentrate on part of the root. For these reasons, teeth that have had root canal treatment are generally considered to carry a higher risk of root fracture than teeth with a living nerve.

In Japan's nationwide survey of the causes of permanent-tooth extraction (8020 Promotion Foundation, 2nd survey, 2018), fracture accounted for 17.8% of extractions, third after periodontal disease (37.1%) and decay (29.2%). The report states that the proportion of fractures was markedly higher in teeth without a living pulp than in teeth with one.

A crown placed 30 years ago has carried decades of biting force. If a crowned tooth starts to feel different, an early examination is advisable.

The main options for replacing a single front tooth are an implant, a bridge, or a partial denture. A bridge is attached to the two neighbouring teeth, which are prepared as supports for a joined set of crowns.

In this case, both neighbouring teeth had also had root canal treatment in the past, so they carried the same higher fracture risk. A bridge would have added the biting load of the missing tooth to those teeth, and was considered likely to increase the chance of them fracturing in the same way in future.

The front teeth also have a large impact on appearance. An implant stands on its own without relying on the neighbouring teeth, protecting them while aiming to restore appearance — including the shape of the gum. For these reasons, an implant was chosen.

Because the labial bone had resorbed, guided bone regeneration (GBR — rebuilding bone with bone graft material and a membrane) was carried out at the same time as the extraction, and the implant was placed in the same surgery (immediate implant placement).

Bone tends to shrink after a tooth is removed. Combining extraction, grafting and placement keeps it to one surgery. The implant position was planned on the CT scan and transferred to the mouth with a 3D-printed surgical guide. Immediate placement on its own does not prevent this post-extraction bone loss, so bone grafting was combined here to rebuild the labial bone. The ITI notes that a thin facial bone wall resorbs considerably more after immediate placement and that a damaged facial wall is a risk factor for gum recession, so careful assessment on CT — including whether bone grafting is needed — is essential.

How firmly an implant is anchored at the moment of placement (primary stability) is assessed by its insertion torque. With limited bone available, the primary stability in this case was 30 Ncm.

Attaching a temporary crown to an implant and loading it straight away (immediate loading) is considered predictable when conditions are favourable, including sufficient primary stability. Because this case combined bone grafting with modest primary stability, the implant was not loaded, and healing until the implant had integrated with the bone was given priority.

In the meantime, appearance was maintained with a temporary tooth bonded to the neighbouring teeth, so the patient did not have a visible gap at the front during healing — without putting any load on the implant.

With a front-tooth implant, the shape of the gum matters as much as the bone. To preserve as much gum tissue as possible, no incision was made (flapless surgery), and a custom healing abutment shaped to the contour of the original tooth at the gumline was connected and left in place for about three months.

A custom healing abutment supports the gum from the inside immediately after extraction and guides it towards the emergence shape of the natural tooth. A 2024 systematic review reported that customized healing abutments predictably shape the peri-implant soft tissue, which can improve aesthetic outcomes compared with standard round healing abutments — while noting that the number of studies is small and follow-up periods are short.

In this case, the gum contour was preserved without a gum (soft-tissue) graft (individual results vary).

After healing, the bonded temporary was replaced with a provisional restoration connected to the implant. With it, appearance, speech, the bite and the gum contour were checked and confirmed.

The final restoration was a screw-retained zirconia crown. It is fixed with a screw rather than cement, so it can be removed for maintenance if needed, and no cement is left below the gumline.

The neighbouring upper lateral incisor (#12) had a crown that no longer fitted well, with decay beneath it. Left untreated, decay under a crown can progress unnoticed, so it was treated at the same time.

After removing the old crown and the decay, the tooth was rebuilt with a fiber post core. A fiber post was chosen over a metal post with the aim of reducing stress concentration on a root that has already had root canal treatment. The tooth was then prepared and restored with a zirconia crown, matched in colour and shape to the new implant crown.

This case used a Hiossen implant, made by the U.S. subsidiary of the Osstem group. The Hiossen implant system is FDA 510(k)-cleared.

According to the manufacturer, the tapered body and thread design are intended to achieve initial stability in soft bone. The surface is SA-treated (sandblasted and acid-etched).

Implant healing generally takes about three months. In a randomized clinical trial comparing three implant surfaces including Osstem SA (early loading in sites healed for at least two months after extraction), stability improved in all groups six weeks after placement, when the definitive restorations were delivered, with no significant difference between surfaces (Körmöczi et al., BMC Oral Health, 2021). Where bone conditions are favourable, an earlier move to the final restoration may therefore be considered for patients who want to shorten treatment. Healing time depends on the bone and on whether grafting is needed; because this case involved bone grafting, about three months was allowed.