The hypomineralised second primary molar is a defect of tooth enamel development that has a reported worldwide prevalence of 6.8% on a child level and 4.1% on a tooth level. The aetiology of hypomineralised second primary molars remain unclear but associations have been reported in the literature with conditions including in vitro fertilisation, alcohol, smoking and hypertension during pregnancy, prematurity, low birth weight, complications during childbirth, fever, asthma and otitis.

The aim of this review was to investigate adverse health conditions in the prenatal, perinatal and postnatal periods associated with hypomineralised second primary molars (HSPM).

Methods

A review protocol was registered on PROSPERO and searches conducted in the Cochrane library, Medline/PubMed, Scopus, Virtual Health Library and Web of Science databases. Two reviewers independently conducted searches and study selection. Observational studies assessing the sociation of prenatal, perinatal and postnatal adverse health conditions with HSPM in children were considered. Data was abstracted and two reviewers independently assessed study quality using the relevant Newcastle-Ottawa Scale.  Odds ratios (OR) and 95% confidence intervals were used where possible and meta-analysis conducted.

Results

• 14 studies (9 cross-sectional, 5 cohort) were included.
• 10 studies (6 cross-sectional, 4 cohort) were considered to have a low risk of bias, 3 cross-sectional had a moderate risk of bias and one cohort had a high risk of bias.
• 7 studies with low and moderate risk of bias contributed to the meta-analyses (see table).

		No. of studies	Odds ratio (95%CI)
Prenatal conditions
	Maternal smoking	2	2.88 (1.62 to 5.15) *
	Maternal hypertension	2	2.91 (1.35 to 6.28) *
	Mother’s alcohol use	3	4.36 (0.45 to 42.00)
	Antibiotics during pregnancy	2	1.27 (0.80 to 2.02)
	Maternal diabetes mellitus	2	0.60 (0.17 to 2.20)
	Infection in pregnancy	2	3.42 (0.51 to 23.05)
Adverse health conditions in the perinatal period
	Low birth weight	3	1.50 (1.15 to 1.96) *
	Prematurity	5	1.93 (1.37 to 2.71) *
	Delivery complications	3	2.42 (1.52 to 3.83) *
	Need for an incubator	3	1.65 (1.01 to 2.70) *
	Type of delivery	3	0.72 (0.50 to 1.02)
	Apgar score	2	1.14 (0.12 to 10.86)
Postnatal factors
	Did not breastfeed	2	1.26 (1.01 to 1.58) *
	Antibiotics use by the child	3	1.24 (1.04 to 1.48) *
	Fever	4	1.37 (1.10 to 1.72) *
	Asthma	2	1.91 (1.16 to 3.13) *
	Pneumonia	2	1.31 (0.81 to 2.10)
	Otitis	2	1.19 (0.41 to 3.47)

* Significant – suggesting an association

Conclusions

The authors concluded: –

Maternal smoking, presence of maternal hypertension, low birth weight, prematurity, delivery complications, need for an incubator, non-breastfeeding, child antibiotic use, fever and childhood asthma were significantly associated with HSPM in low heterogeneity meta-analyses.

Comments

The authors pre-registered their review protocol and followed a standard systematic review process. While a good number of studies were identified the majority were cross-sectional in design where ideally a prospective cohort design with detailed data capture of potential associated factors is required. Not all the included studies were able to contribute to the meta-analyses because of incompatibilities in study methodology and only a small number of studies assessed the same health condition. Consequently, although a number of conditions were positively associated with HSPM the findings should be interpreted cautiously. Additional high quality well-reported studies would be needed to further clarify any strong association between the prenatal, perinatal and postnatal exposures and HSPM.

Links

Primary Paper

Lima LJS, Ramos-Jorge ML, Soares MEC. Prenatal, perinatal and postnatal events associated with hypomineralized second primary molar: a systematic review with meta-analysis. Clin Oral Investig. 2021 Dec;25(12):6501-6516. doi: 10.1007/s00784-021-04146-6. Epub 2021 Aug 19. PMID: 34414520.

Review protocol in PROSPERO

Other references

Dental Elf – 29^th Nov 2021

Hypomineralised second primary molars

Dental Elf – 7^th Aug 2020

Hypomineralisation and drugs used during pregnancy and infancy