The same approach can be taken for HSPM. Similar treatment approaches exist in the management of hypomineralised primary teeth: prophylaxis, regeneration, non-invasive therapy, temporary and permanent therapy as well as extraction (Elfrink and Weerheijm 2020).

The structure of the flow chart is similar to the MIH-flow chart (Fig. 1): in the first horizontal row, the four indices (HSPM-TNI 1–4) are shown. In the first column, all available treatment approaches are displayed: prophylaxis (at home, in office), non-invasive therapy, temporary therapy (GIC, SDF or SDF + GIC), permanent therapy (filling or prefabricated crown) and extraction. The flow chart should be read in such a way that after the diagnosis (TNI 1–4), the user can find the treatment options in the appropriate column.

Treatment plan based on the HSPM-TNI

Prophylaxis is not only important in MIH affected patients but also in children showing HSPM as both groups have a higher caries risk (Lygidakis et al. 2022; Ben Salem et al. 2023). Higher prevalences of dental caries in MIH/HSPM children compared with non-affected ones were found by Ben Salem et al. in a recent review (Ben Salem et al. 2023). Therefore, prophylaxis should be performed directly after hypomineralised teeth eruption independently of the severity of the diagnosed TNI. Fluoridated tooth pastes should be used twice a day at home. Topical fluoride varnish can be applied ‘in office’ 2–4 times per year depending on caries risk (Toumba et al. 2019). The additional use of mineral containing agents (e.g. calcium glycerophosphate (CaGP), casein phosphopeptide amorphous calcium phosphate (CPP-ACP), or casein phosphopeptide amorphous calcium fluoride phosphate (CPP-ACFP)) are recommended to hypomineralised lesions with mineral deposition (Sezer and Kargul 2022).

Non-invasive therapy strategies include sealings. One possibility is the use of a sealant or flowable in combination with an adhesive if the tooth is fully erupted and the child is compliant. Another option is the application of a glass ionomer cement (if the tooth is not fully erupted or if there is a non-compliance).

The original flow chart for MIH includes two temporary therapy options: short-term (therapy C) and long-term (therapy D). Regarding HSPM, no subdivision is needed. Therefore, this flow chart only includes therapy C. First, temporary treatment approaches include the application of a glass ionomer cement in case of defects (dimension < 2/3 of the surface) being present. Glass ionomer cements that are less technique-sensitive and can be placed in only one increment, favouring clinical management (Amend et al. 2022). If caries is present and the child is non-compliant SDF without/with GIC might be considered as treatment of choice (BaniHani et al. 2022).

The following treatment options can be considered definitive for the restoration of primary teeth: restorations using composite or compomer materials and preformed crowns (stainless steel or zirconia) (Amend et al. 2022). When applying crowns, a distinction can also be made between the conventional approach and the Hall technique (BaniHani et al. 2022; Hu et al. 2022).

The therapy plan is finalised with therapy F, extraction. In severe cases, when primary molars show severe post-eruptive breakdowns, the pulp is involved or dental abscesses are present, extraction should be the treatment of choice in HSPM. The indications are similar to the management of MIH (Lygidakis et al. 2022).

For hypomineralised primary teeth that do not show any post-eruptive breakdowns or hypersensitivity (HSPM-TNI 1), prophylaxis/regeneration is the starting point. In addition to this, the sealing of the fissures could be an option. If the tooth is fully erupted, this procedure should be carried out with a conventional fissure sealant or a flowable with the pre-application of an adhesive (Lygidakis et al. 2009). If the molar has not yet fully erupted, a temporary fissure sealant should be applied using a low viscosity glass ionomer cement.

A TNI 2 is defined as substance loss being present and hypersensitivity being absent. If the breakdown is not located in the fissure and involves < 1/3 of the surface of the tooth, sealing therapy (B) may be a first step in the management of HSPM beside prophylaxis. If the breakdown is found in the fissure, the defect is up to 2/3 or close to the pulp, and the child is not compliant, a temporary therapy (C) using a GIC is the option of choice. If, in addition to non-compliance, caries is also present, SDF can be used with or without GIC (C2, C3) (Zaffarano et al. 2022, Inchingolo et al. 2023). Permanent restorations (E) include the use of composite or compomer-based fillings (Amend et al. 2022). Alternatively, a prefabricated (preformed) stainless steel crowns can be chosen (D) (Declerck and Mampay 2021; Amend et al. 2022). The preparation technique can be conventional (both materials) or Hall (stainless steel crown, (Innes et al. 2007)). For larger defects (TNI 2c), especially where there is a risk of compromising pulp integrity, prefabricated zirconia crowns may be an option for restoration. However, due to the large loss of substance during preparation for this restoration, there is a high risk of artificial pulp opening in less severe cases (Mohn et al. 2022, Sparks et al. 2022). In severe cases (TNI 2c), extraction is also an option.

Hypersensitive hypomineralised primary molars with no breakdown can be sealed. Thereby, resin-based sealants in combination with an adhesive can be applied similar to the treatment of MIH (Lygidakis et al. 2022). If the tooth has not fully erupted and the child is not cooperative, sealing with a low viscosity glass ionomer cement (B2) can also be performed.

In the case of the presence of a substance loss and hypersensitivity, the treatment plan is similar to the options presented for the TNI 2. The size and location of the defect is important. Minimal breakdowns that do not occur in the fissure can be sealed. Temporary therapy options include the application of GIC when defects can be found in the fissure or if the breakdown is > 1/3 or > 2/3 in its extension or close to the pulp. In case of non-compliance and caries being present, the application of SDF without/with GIC should be considered (Zaffarano et al. 2022, Inchingolo et al. 2023). Permanent restorations (E) comprise the use of composite/compomer fillings or of prefabricated crowns (stainless steel or zircona) (Amend et al. 2022). Extraction marks the end of increasingly invasive methods and must be considered in severe cases with breakdowns of more than 2/3 of the crown.