A Sales Representative, a Laser Protocol and a Retrospective Case Series
A 52-year-old woman attends a private clinic with a previously root-treated tooth 46. It is asymptomatic, restored with a cast post and crown, and a radiograph shows a 5 × 6 mm periapical radiolucency. Meanwhile, the clinic owner has bought a laser-activated irrigation unit and asks you to offer it as a standard adjunct, quoting a distributor-supplied retrospective case series of 38 teeth followed for 6 months, which reports 95% success with no control group and no statement of lesion size or pulp status. The distributor offers a per-case honorarium and invites the clinic to co-author a further case series; the owner also proposes to extract the records of all endodontically treated patients from the last year for the study without contacting them. You are asked to advise.
1. Appraise the evidence for the laser-activated irrigation protocol and decide whether to adopt it as standard care.
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What the study can and cannot show. This is a single-arm retrospective case series: no control, no randomisation, no blinding, no sample-size calculation and no pre-specified outcome. With 38 teeth and 95% success, the 95% confidence interval runs roughly from 82% to 99% - two additional failures would materially change the estimate. Six months is too short: periapical healing must be judged at 12 months or more, ideally using a validated index such as the periapical index (PAI) with two calibrated examiners. Case selection is unknown: lesion size, pulp and periapical diagnosis, number of visits, irrigant regimen and operator skill all confound the result, and clinicians tend to select easy cases when evaluating a new device. Success is also defined vaguely, and without a control group we cannot separate the device from good conventional technique.
Biological plausibility. Laser- and ultrasonically activated irrigation improves irrigant exchange and biofilm removal in laboratory models, but laboratory findings frequently fail to translate into measurable clinical benefit, and the existing randomised trials of activation methods have not demonstrated a clear superiority in healing.
Decision. I would not make the device standard care. The current standard remains adequate shaping, sodium hypochlorite at a documented concentration and volume with activation, EDTA, and a hermetic seal. Adoption would be defensible within a registered, ethically approved randomised trial or with explicit patient consent and disclosure that benefit is unproven and there is an additional cost. The owner should be told that changing a departmental protocol on this evidence creates both clinical and reputational risk.
2. Identify the ethical, regulatory and authorship problems in the owner's proposal and state what should happen instead.
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Retrospective chart review. Using identifiable records without patient contact is research on human subjects. It requires prospective approval from an institutional review board or research ethics committee, a data protection plan, minimal necessary data collection, secure storage and a documented basis for any waiver of consent. The fact that the data already exist does not remove that obligation, and in many jurisdictions using the records for a publication without approval is a reportable breach. The correct route is an application to the ethics committee with a protocol, a data-management plan and a statistical analysis plan.
Conflict of interest. A per-case honorarium from the equipment distributor creates a direct financial incentive to use the device and to report favourable results. If it is accepted at all, it must be declared to the ethics committee, to patients and in any publication, and it must not be linked to the number of cases treated or to the findings. The safer option is to decline it. The clinic's marketing must not describe the technique as proven or superior.
Authorship. Authorship requires a substantial contribution to conception, design, acquisition or interpretation, drafting or critical revision, final approval, and accountability for the work. Supplying equipment or funding does not qualify; a distributor representative belongs in the acknowledgements, not the author list. Gift or reciprocal authorship is research misconduct.
Patient consent for treatment. Any patient offered the adjunct must be told that it is unproven, that conventional treatment is available, what the extra cost is, and that refusal will not affect their care. Consent must be documented. Separately, the woman with tooth 46 needs a clinical decision based on her own findings, not on the clinic's equipment purchase.
3. How would you counsel the 52-year-old patient about tooth 46, incorporating the uncertainty about adjunctive technologies?
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Findings. Tooth 46 has been root-filled and has a cast post and crown. It is asymptomatic but has a 5 × 6 mm periapical radiolucency, which most often represents persistent intraradicular infection, though a stable scar or a true cyst is possible. The absence of symptoms does not mean the lesion is harmless, and the post makes retreatment technically demanding.
Options and reasoning. (1) Monitor with radiographs at 6–12 months if the tooth is comfortable, the restoration is sound and the lesion is small and not enlarging; some persistent lesions remain stable for years. (2) Nonsurgical retreatment, which requires removing the post with a real risk of root fracture and may require replacing the crown; success for retreatment of apical periodontitis is roughly 80–85% in favourable cases, less with a post. (3) Apical microsurgery with root-end resection and filling, which avoids post removal and directly addresses the lesion; success is similarly around 85% with modern technique. (4) Extraction and eventual implant, which is predictable but irreversible and costly.
The technology question. I would explain that laser-activated irrigation and similar adjuncts have plausible laboratory benefits but no reliable clinical evidence that they improve healing, and that they add cost. The standard that matters is complete cleaning and shaping of all canals, adequate sodium hypochlorite with an EDTA final rinse, and a good coronal seal. She should not feel that choosing not to pay for an unproven device reduces her care.
Plan. A CBCT would clarify the anatomy, the post and the lesion before deciding between monitoring and surgery. I would document the discussion, record her preference, and make clear that a decision to monitor is contingent on review at a defined interval. If she chooses surgery, the informed consent must include nerve injury, bleeding, and the possibility of extraction, as with any posterior mandibular apical procedure.