The present retrospective study of dental records for 3–19-year-old extremely preterm–, very preterm–, and full term–born children and adolescents supported our hypotheses for many of the investigated variables. At younger ages, 3–6 years and 7–12 years, preterm children missed significantly more dental appointments and had more notes on BMP in their check-up and treatment records than their full term–born counterparts. Overall, the present study has yielded valuable information for future considerations in the dental care of preterm–born adults; one main result is that both preterm– and full term–born children can be offered the same dental care, which is a welcome result from both patient and care provider perspectives.
Ghanei et al. found that, in general, 19.3% of the time, children experience pain and 17.7% of the time, discomfort during dental radiographic examinations . The findings of the present study show that premature birth does not seem to be an important factor in BMP during radiographic examinations, although they can be painful and uncomfortable. Other findings support this. Our study sample had also participated in a previous questionnaire survey at age 17–19 years ; 34% of the extremely and very preterm–born respondents claimed experiencing pain (a rating of ≥ 50 on a Visual Analog Scale [VAS] scale) in dental radiography examinations compared with 37% of the full term–born respondents. This study of Brogårdh-Roth et al., however, did document a significant gender difference in both preterm groups as well as in the control group and revealed that 17–19-year-old adolescents who had been extremely preterm at birth reported pain during dental radiography more frequently than the very preterm–born adolescents . The Brogårdh-Roth et al. study  also reflected that the views and experiences of the adolescents themselves are important; Marshman et al. have similarly stated that it is necessary for dental research to acquire the adolescent perspective in future evaluations of treatment .
The overall aim of the present study, however, was a longitudinal overview of the dental care given to preterm– and full term–born patients during their growing up years without focusing on the patient perspective. At all age intervals, preterm–born children and adolescents with a history of oft-reported chronic illness need to be identified in order to determine suitable pain management strategies, which was also highlighted by Hatfield et al. . Johnson and Marlow concur, for the reason that cognitive deficits are often reported in extremely and very preterm–born individuals . Pierro et al. found that age is significantly related to behaviour during radiographic examinations because cooperation increases with age , which agrees with our findings.
Regarding the documentation of dental radiographs in the dental records, this study found that almost no dental professional documented why bitewing radiographs were necessary. This is most likely because Sweden had no national regulations for recording justifications for use of ionizing radiation at the time of our study. Regulations were introduced first in 2018 . Justification of periapical and panoramic radiographs, however, was usually documented. This might be a consequence of the situation during which these dental radiographs were taken or that they served as an answer to a specific clinical problem.
Our study found no significant differences in mean numbers of periapical and panoramic radiographs between preterm–born and full term–born children at any age interval. Nevertheless, the mean number of bitewing examinations was significantly higher in full term-born children than in very preterm-born children. This could be due to the fact that before, in Sweden, children were examined in groups. Bitewing radiographs were exposed regularly on every child. Probably, some of the preterm-born children were not included in this type of screening. Preterm–born children still appear to have undergone the same radiographic examination procedures as full term–born children, with similar exposures to radiation. However, from 3–6 years of age, both the very preterm– and extremely preterm–born presented with more BMP during dental examinations and various treatments compared to the full term–born controls; furthermore, during ages 7–12 years, the very preterm–born patients also presented with more BMP than the controls. Yet, this did not occur during dental radiographic examinations compared to full term–born children.
Reports of preterm–born children having more behavioural and emotional problems than full term–born, as Johnson and Marlow have observed , may help explain why the two preterm groups in our study presented with more BMP during dental examinations and treatments at ages 3–6 and 7–12 years. This difference disappeared at 13–19 years, which may be due to the adolescent phase being a time of greater maturity and, thus, the preterm–born adolescent being able to adjust to dental care situations better; several studies on preterm–born adolescents have reported similar observations [4, 6, 21, 24].
Behaviour in the dental situation, however, may be linked to behaviour in everyday situations, and there are reports that preterm–born children have problems with social and behavioural functioning that manifest when they reach school age and adolescence; Rogers and Hintz have noted that these include hyperactivity, anxiety, and difficulties focusing . Brogårdh-Roth et al. found in one study that negative experiences are an important factor in the development of dental fear and anxiety; this was not a factor, however, for the same participants at ages 17–19 years. In this follow-up study, dental fear and anxiety in the preterm–born adolescents were comparable to in the full term–born control group .
Klaassen et al. showed that the most common reason for referral to a paediatric dental specialist was uncooperative behaviour . Our study found no significant differences between preterm– and full term–born children in number of referrals to paediatric dental specialists, which indicates that although preterm–born children may present with more BMP during dental examination and treatment, general-practicing dentists are still able to manage these patients. The lack of a significant difference in mean number of visits for behaviour shaping between our experimental and control groups supports this.
In line with many other studies, we found no significant difference in caries prevalence between preterm– and full term–born children [7, 33, 34, 35, 36]. Also in line with Johnson and Marlow, however, are the findings in our study that extremely preterm– and very preterm–born children and adolescents have more chronic illnesses than full term–born children and adolescents at all age intervals . The Brogårdh-Roth et al. study on the same participants as in our study found that about 50% of the preterm– and full term–born adolescents reported consuming sweets and sugary drinks between meals several days per week at 17–19 years of age . As Hasselkvist et al. have noted, this frequent consumption of sweets and soft drinks may be a risk factor for developing caries and, later in life, dental erosion . Further, Sharafi et al. have shown that this less-than-healthy lifestyle throughout young adulthood increases cardiovascular disease in young adults born preterm ; thus, there is risk of problems in adulthood.
In our study, extremely preterm–born children was the group that missed most appointments at ages 3–6 years while very preterm–born children missed most appointments at ages 7–12 years. Preterm–born children have more medical appointments than full term–born children, which may explain this difference. By ages 13–19 years, however, the difference had disappeared, probably because the need for medical care is less as the adolescent matures.
In line with the study of Brogårdh-Roth et al., which found that preterm–born children are not more exposed to traumatic dental injuries than full term–born children, we found no difference in mean number of dental emergency visits between our experimental and control groups . We also found no differences in orthodontic treatment experience, although Paulsson et al. have reported a higher treatment need in preterm–born children than full term–born children . Nonetheless, Paulsson et al. showed in another study that extremely preterm–born children can experience delayed tooth development, which the general practicing dentist should note .
Deciphering handwritten dental records can be challenging. How and when the records are written, whether at the end of the day, or during the patient visit, as well as which dental care professional who writes them, may lead to an inaccurate portrayal of the actual problems, especially of BMP. Further, statistical comparisons between the two preterm groups should be interpreted with caution as the extremely preterm–born group had only 33 participants; the group size, however, was in line with official Swedish statistics concerning prevalence of birth between 23 and 28 weeks of gestation.
Our study followed the same groups of preterm– and full term–born children and adolescents over a long period (3–19 years of age), which can be considered a strength. Further, the original preterm study population included all adolescents born at ≤ 32 gestational weeks in the catchment area of Malmö and Lund in southern Sweden from 1994 to 1996. Participation was relatively high; thus, the data could be helpful in determining population norms.
Another strength of the study was that one examiner (AV) retrieved all notes from the dental records in collaboration with a specialist in paediatric dentistry (SBR) and a specialist in Oral and Maxillofacial Radiology (KH-H). Well-defined, standardized methods were used in the dental record review.