Dr Felicity Borrie, Dr Nicola Innes

Should I extract every six?

BOSF Grant


University of Dundee/NHS Tayside


This clinical trial investigates relative benefits (clinical effectiveness, and quality of life) of two extraction patterns when lower first permanent molars are extracted in children: the conventional treatment where current guidance is followed and extraction of the upper FPM is carried out, compared with the intervention where there is no compensation extraction of the upper FPM following extraction of the lower FPM.


To determine whether compensating extraction of upper FPMs following loss of lower FPMs in children is of benefit. The particular benefits being investigated are related to the resulting occlusion, patient experience and oral health related quality of life. The follow up will extend over a period of 5 years or until the patient is 14 years of age – whichever is earlier.


A multi-centre, two-arm parallel group, randomised clinical trial using a superiority framework, set in Primary and Secondary Care settings


Intervention – extraction of lower FPMs only.
Control – following RCS Eng Guidelines; extraction of lower and opposing upper FPMs.


Children, aged 7-11 years (n=400) requiring extraction of a lower FPMs


The primary outcome measure is extent of tipping of the lower second permanent molar with a favourable outcome being a degree of tipping less than 15° and unfavourable outcome being greater than 15°.

The secondary outcomes are; residual space between the lower second premolar and lower second permanent molar; dental and orthodontic treatment during the follow-up period; quality of life; use of LA, IHS and GA for treatment; and, over-eruption of the upper FPM for the intervention group where this tooth has been retained.


Extraction of first permanent molars (FPMs) children is common. When lower FPM extraction is planned, current Royal College of Surgeons of England (RCS Eng) guidelines recommend a ‘compensating extraction’ (removal of the upper FPM to prevent its over eruption). However, uncertainty amongst clinicians as to whether the compensation extraction is necessary means that some clinicians follow the guidelines, and others do not. As a result, children may be having unnecessary extractions carried out or may be failing to receive extractions required to achieve optimal long-term oral health. The decision to extract fewer or more teeth can impact on the management options needed to support the child with the surgical procedure(s). For example, if a single FPM extraction is required, a child may be able to cope with local anaesthetic (LA) injections, while for two or more FPMs, LA alone may be inadequate and inhalation sedation (IHS) or general anaesthetic (GA) may be required. Therefore many children may be undergoing significant surgical procedures when there is no benefit to their oral health, at considerable cost to the child, family and the healthcare system.

The SIXES (Should I eXtract Every Six) Dental Trial will investigate clinical effectiveness and quality of life for conventional treatment (following the guideline of compensation extraction of the upper FPM) compared with the alternative intervention (removal of lower FPMs but no extraction of the upper FPM).


The SIXES Dental Trial is a multi-centre, two-arm parallel group randomised clinical trial. Dundee Dental Hospital Paediatric/Orthodontic staff and General Dental Practitioners (GDPs)/practice-based Orthodontists will recruit 400 children, aged 7-11 years requiring extraction of a lower FPM but who have upper FPMs of good prognosis. Baseline measures (prior to treatment) and outcome data (at one year and at five years, or when the patient reaches 14 years of age) will be assessed through study models and paper based questionnaires to the child and parent.

The primary outcome measure is degree of tipping of the lower second permanent molar.

The secondary outcomes are; use of LA, IHS or GA for treatment provision, residual spacing (between lower second premolar and lower second permanent molar); orthodontic treatment requirement, quality of life, and over-eruption of the upper FPM in the intervention group.


Currently dentists and orthodontists face a dilemma in clinical decision-making in this area, relying on the lowest level of evidence, expert opinion. SIXES will provide evidence to support decision-making and inform practice. Should this study find the procedure to be unnecessary, it will result in a reduction in the number of teeth extracted. The impact of the study would then be significant for children and their carers, as well as providers and purchasers of dental treatment.