Does early cervical headgear treatment influence the eruption of canines?

Orthodontists traditionally used cervical headgear to correct molar relationships and attempt to correct Class II skeletal discrepancies. In the past decade, its use has declined, partly due to advances in anchorage, such as TADS, and the perception of low patient cooperation. Nonetheless, we can still learn from long-term research on the effects of headgear.

This paper reports the findings of an RCT on the early effects of cervical pull headgear. It is notable because it follows a study that the team started in 2008.

In this report, the team looked at the effect of headgear on the eruption and position of the permanent canines and molars.

What did they ask?

They did this study to 

“Investigate the effects of early vs late cervical headgear treatment on eruption time of maxillary canines and second molars”.

What did they do?

They did a randomised controlled trial with a 1:1 allocation of treatment timing. The PICO was 

Participants: 7-year-old children with Class II occlusion with overjets greater than 6mm and a deep bite. The investigators identified the children from a school screening programme from February 2004 to June 2008.

Intervention: Standard cervical pull headgear when the patients were approximately 7 years old. This was the early treatment group. 

Comparison: No active treatment. They observed this group for 18 months. After this time they treated them with cervical pull headgear. This was the later treatment group.

Randomisation was done using sealed envelopes and was prepared in advance of the study. One of nine general dental practitioners did the treatment.  The follow-up period ended in 2018.

Blinding of operators and patients was not possible. They analysed the data blind.

The team have done previous papers on this study. I have also written posts about the study that has looked at the effects on the airway, path of eruption of the maxillary canine, and dental arch dimensions. 

The primary outcomes of this paper were the positions of the teeth derived from dental panoramic tomographs. They took these at five time points T0 (age 7.3 years), T1 (9.6 years), T2 (11.5 years), T3 (15.3 years) and T4 (17.8 years).

They analysed the data using linear mixed models.

What did they find?

By the end of the study period, half of the participants had dropped out of the trial. 

The study team provided a substantial amount of detailed data on tooth positions. This presentation was fairly complex, and I do not have the space or time to display all the information. If you want more details, you should read this open-access paper.  

Their main finding was that later treatment seemed more advantageous than early treatment regarding the position of the permanent canines. These teeth erupted earlier and were more vertically aligned than in the early group. Similarly, later treatment led to better vertical inclination and earlier eruption of the second permanent molars.

Their final conclusion was:

“Later treatment was more beneficial than early treatment for the permanent canines and second molars”.

What did I think?

This report presents some additional outcomes from an ambitious and complex randomised controlled trial. This study required an incredible amount of work. Since the study began in 2008, it is easy for us to criticise the methodology now, as our trial methods have since improved. I have mentioned this in my earlier posts. 

The most significant issue with this long-term report is that it has lost 50% of its participants. However, retaining only 50% is a considerable achievement. Nonetheless, we must exercise caution when interpreting the findings, as the study is likely at high risk of response bias. Unfortunately, we do not know the direction of that bias.

Nevertheless, their results indicate that there are few benefits from early headgear treatment. Their findings are consistent with several other studies examining early interceptive treatment and may challenge the effectiveness of early or Phase I treatment. 

Does early treatment make a difference? I’m not so sure.

Key points

• Decline of traditional headgear use in orthodontics: Despite its historical role in correcting molar relationships and Class II discrepancies, the use of cervical headgear has decreased due to advances like TADS and concerns about patient cooperation.
• Importance of long-term research on headgear effects: The study emphasises the value of long-term research, as it provides insights into the effects of headgear on dental development over the years, which can inform current practices.
• Focus of the study on eruption and position of permanent teeth: This randomised controlled trial investigated how early versus late cervical headgear treatment influences the eruption timing and positioning of permanent canines and molars.
• Study methodology and participant details: The trial involved 7-year-old children with Class II occlusion, using a 1:1 randomisation to early treatment with headgear or delayed treatment, with follow-up until 2018.
• Main findings and implications for treatment timing: The results suggest that later treatment may be more advantageous, with earlier eruption and better alignment of permanent canines and molars; however, response bias due to participant dropout should be considered.