Howarth Elevator and Mitchell Trimmer: Oral Surgery Tools

A lower third molar, distoangular, half covered by bone. The incision is made, and the surgeon’s next thirty seconds decide how the next forty minutes go. Get a clean plane between periosteum and cortex on the first pass and the flap lifts as one sheet, retracts without tearing, and closes over sound bone at the end. Tear it, and you spend the case fighting a shredded flap that bleeds into the field and heals badly.

Two instruments do most of that work in oral surgery, and they are usually on the same tray: the Howarth periosteal elevator and the Mitchell trimmer.

Where the Howarth came from — and why that matters

The pattern is a borrowed one. Walter Howarth designed it as a nasal rasparatory for submucous resection of the septum, where the requirement is to separate mucoperiosteum from cartilage and bone in a narrow corridor without perforating a membrane that is under a millimetre thick. Oral surgery took the instrument over largely unchanged, because the anatomical problem is the same: a thin, tough, adherent membrane that has to come off intact.

That origin explains the geometry. The Howarth periosteal elevator is double-ended, with two long slender shafts running from a flat central handle. Overall length varies by pattern — commonly 180 mm to 215 mm, with 215 mm (8½ inch) the length most often catalogued for the classic Howarth. One working end carries a narrow flat blade, usually 3 to 4 mm wide, with a squared or slightly rounded leading edge. The opposite end is broader, commonly 5 to 6 mm, and often given a shallow curve so it can follow a convex buccal cortex.

The long shaft is the point. It lets the working end reach the distal aspect of a lower eight while the surgeon’s hand stays out of the mirror’s line and clear of the assistant’s suction.

The flat handle

The central handle is flat rather than round on most patterns, sometimes with a fine cross-hatched or diamond knurl. Round handles roll under a wet glove. A flat handle also gives you rotational reference: you know which way the blade face is pointing without looking, which matters when the working end is out of sight under a reflected flap.

The Mitchell trimmer

Also a double-ended instrument, shorter at around 165 to 175 mm, and the pairing is deliberate rather than accidental. The Mitchell trimmer carries a small spoon-shaped excavator at one end — typically 2.5 to 3.5 mm across the bowl — and a flat, slightly angled blade at the other.

It does three jobs a Howarth cannot do well:

Starting the reflection. The spoon end slips under the interdental papilla and lifts it off the interproximal bone. That first millimetre of separation is the hardest and the most likely to tear, because the papilla is tethered by transseptal fibres. A narrow spoon works there; a 5 mm flat blade does not.

Curetting. Removing the follicular sac from around an impacted crown, clearing granulation tissue from a socket, debriding a periapical lesion after apicectomy. The bowl edge is sharpened for this.

Trimming. The original name refers to trimming bone and soft tissue at the margins of a surgical site — smoothing a sharp interseptal crest, tidying a socket rim before closure.

Howarth versus Mitchell versus the alternatives

The Warwick James row is worth reading twice. Tooth elevators and periosteal elevators end up in the same kidney dish and get confused. A Warwick James has a bevelled, sharpened tip built to wedge into the periodontal ligament space and transmit rotational force to a root. Used against periosteum it perforates the flap; used the other way round, a Howarth blade bends. Our comparison of dental luxators and elevators for extraction sets out where each of those belongs.

Flap design decides which end you use

Instrument choice follows the incision, not the other way round. Three designs cover most oral surgery, and each loads the instruments differently.

Envelope flap. A sulcular incision along the gingival margin with no vertical relieving cut, extended one or two teeth either side of the surgical site. Blood supply is excellent and closure is simple because the flap returns to its own margins. The cost is access: to expose bone apically you have to reflect a long flap, which means the whole length of the reflection is done by pushing along cortex. This is the design that most rewards a long-shafted Howarth, and the one where a Mitchell spoon is essential at every papilla along the run.

Triangular flap. An envelope plus a single mesial relieving incision, usually placed at the line angle of the tooth rather than over the papilla or over a bony prominence. Access improves sharply for the same length of sulcular incision. The instrument consequence is that the relieving incision has a corner, and corners tear. Reflect the corner first, working from the vertical limb into the sulcular limb, and keep the elevator blade fully seated on bone as you turn it.

Ward’s incision. The standard approach for a mandibular third molar: a distobuccal relieving limb running from the distal aspect of the second molar up the external oblique ridge, joined to a sulcular incision. Reflection here is almost entirely a pushing stroke along the ascending ramus, which is why the narrow 3–4 mm Howarth end is used first and the broad end takes over once the plane is established.

Two rules apply across all three. The base of the flap must be at least as wide as its free margin, or the apical portion outruns its blood supply. And a relieving incision should never end over the surgical defect — the closure line needs sound bone underneath it, or it dehisces.

Technique: raising a flap that survives retraction

The sequence that works is the same whether the flap is an envelope design or a triangular flap with a mesial relieving incision.

1. Cut to bone. The single most common cause of a torn flap is an incision that only went through mucosa. The blade must contact cortex along the whole length of the incision, including at the base of a relieving incision.
2. Start at the papilla with the Mitchell spoon. Concave surface toward the bone, tip engaged in the interdental space, lift rather than push. Two or three papillae, not the whole arch.
3. Switch to the Howarth. Blade face flat against bone, bevel toward the bone, and advance with a pushing stroke — not a levering one. The instrument should be sliding on cortex, and you should feel it, not the flap.
4. Keep the blade loaded against bone. The moment the working edge lifts off cortex it is in periosteum, and periosteum is what tears. If you lose the plane, come back to a point where the plane is clean and re-enter.
5. Reflect past the mucogingival junction before retracting. A flap held under tension at its base is a flap that will tear at the corner and heal with a scar band.
6. Hold, don’t stretch. The broad end of the Howarth rests against reflected bone and holds the flap passively. Retraction force belongs on bone, not on the soft tissue margin.

The lingual retraction question

A Howarth is frequently used as a lingual retractor during mandibular third molar removal, raised subperiosteally on the lingual aspect to protect the lingual nerve from the bur. The evidence on this is genuinely mixed and any honest instrument guide has to say so: systematic reviews of lingual flap retraction during third molar surgery consistently report a higher rate of temporary lingual nerve dysfunction in retracted cases, alongside comparable or lower rates of permanent injury.

The instrument is not the variable there — the decision to raise a lingual flap at all is. Where a unit’s protocol does include lingual retraction, a Howarth with a smooth, unsharpened broad end and no burr on the edge is the correct tool for it; a sharp-edged or nicked blade is not.

Beyond exodontia

Apicectomy. After a semilunar or rectangular flap, the Howarth holds the flap clear of the osteotomy while the root end is resected. The Mitchell spoon then enucleates the periapical lesion. This pairing is essentially the whole soft-tissue instrument set for the procedure.

Implant and grafting surgery. Full-thickness reflection over an edentulous ridge, then holding the flap while the osteotomy is prepared. Broader elevators take over for wide exposures, but the Howarth remains the instrument for reflecting at the crestal line and around adjacent teeth. Instrument selection for that work is covered in our dental implant instrument kit guide.

Cyst enucleation. Mitchell spoon against the bony wall, working around the cyst lining. The spoon edge has to be sharp for this or the lining fragments and leaves remnants.

Alveoloplasty. Flap reflection with the Howarth, then the Mitchell flat end for smoothing after rongeur or bur work.

Steel, hardness and edge

Both instruments are made from martensitic stainless steel — AISI 420 for the working ends where an edge is required, hardened and tempered to roughly 50 to 56 HRC. That band is a compromise. Harder steel holds a sharpened spoon edge longer but chips against cortical bone; softer steel rolls its edge and needs re-dressing every few cases.

A few specification points that separate a serviceable instrument from a disposable one:

• One-piece construction. The best patterns are machined from a single bar. Instruments with a soldered or welded joint between shaft and working end fail at that joint under retraction load, and they fail without warning.
• Edge geometry on the Mitchell spoon. The bowl should be sharpened on its outer circumference to a defined bevel, not left as a stamped rim. An unsharpened spoon crushes rather than cuts and will not enucleate cleanly.
• Blade edge on the Howarth. Squared and smooth, deliberately not knife-sharp. A cutting edge on a periosteal elevator perforates flaps. Run a gloved fingertip along the leading edge on receipt; a burr or a nick means the instrument was finished carelessly.
• Passivation. A properly passivated instrument carries a uniform chromium-oxide layer. Untreated surfaces pit at the working end first, where the finish is thinnest, and pitted steel harbours protein residue. Our note on surgical instrument passivation covers what to ask a supplier about this.
• Handle finish. Satin, not mirror. Mirror finish reflects operating light back into the surgeon’s eye at exactly the angle these instruments are held.

Reprocessing and service life

Neither instrument is hinged or lumened, so reprocessing is straightforward: enzymatic pre-soak, ultrasonic cleaning, thermal disinfection, then a standard 134°C prevacuum steam cycle. No lubrication is needed — there is no joint.

What kills these instruments is bone contact, not sterilisation. Expect the Mitchell spoon edge to need re-dressing after a few dozen cases of active curettage, and inspect the Howarth blade edges at every set assembly for the two failure modes that matter: a rolled or burred leading edge, and a bent shaft. A shaft bent even slightly means the instrument has been used as a lever against a tooth or a bony ledge, and its working end will no longer sit flat on cortex.

Practical inspection at set assembly takes about ten seconds per instrument: sight down the shaft for straightness, run a fingertip along the blade edge for burrs, check the spoon rim for chips, and confirm the handle knurl has not worn smooth. Full details of what a receiving inspection should cover are set out in our instrument QC checklist for buyers.

What to specify when ordering

Dental instrument catalogues are inconsistent about these two patterns, and the same name covers noticeably different geometries between makers. Specify:

• Overall length in mm, not “standard”
• Blade width at each end for the Howarth, in mm
• Spoon bowl diameter and whether the rim is sharpened, for the Mitchell
• Steel grade and target hardness range in HRC
• Handle profile — flat or round — and finish
• Single-piece construction, explicitly

A specification written that way makes samples comparable between suppliers. Without it, a quoted price difference of 40% usually turns out to be a difference in construction rather than a difference in margin. The full dental instruments range lists these dimensions per pattern.