A branch of Supply Chain Management focuses on the evaluation of supplier-buyer relationships, in order to understand the determinants of a successful relationship, especially in terms of long-term continuance of the relationship itself [1–4].
Two of the dimensions mostly investigated by scholars as influencing the success of business relationships are service quality and relationship quality. For example, Ulaga and Eggert  identified benefits and costs building the relationship value dimensions. Among the benefits, they mentioned service support and personal interaction as dimensions characterizing the relational aspect, in addition to more traditional dimensions characterizing the service quality aspect (product quality and delivery performance).
Scholars agree that the evaluation of business relationships should consider not only service quality aspects, but also customers’ and suppliers’ mutual perceptions related to the quality of the relationship. Indeed. as stated by Cannon and Perreault , “customer evaluations of supplier performance and satisfaction with relationship represent important outcomes in business exchange”. Coherently, some researchers studied how to evaluate the performance of inter-organizational relationships, often stressing the importance of the relational dimension as a key determinant of the overall relationship performance. For example, Giannakis  proposed a framework for the assessment of the performance of supplier relationships, applicable both to the manufacturing and services contexts. This model took into consideration both the supplier and the customer perspectives, measuring their perceptions related to the nature of the relationship, the relational performance of the other party and their own relational performance.
Another example is the work by Benton and Maloni  that investigated the relationships between service outcomes, relationship quality, supplier satisfaction and relationship performance, both from the customer and the supplier perspective in the automobile sector. They discovered how the positive effect of service quality outcome on supplier satisfaction was completely mediated by the effect of supplier-buyer quality of relationship. This finding implies that in assessing overall performance of a relationship, what is most important is the relational dimensions, rather than the service outcome.
Most of the studies dealt with relationships belonging to the private sector. Whereas, in the public sector only few attempts have been made to investigate the performance of inter-organizational relationships in the supply chain context [7–8]. One example is a study  that developed a framework for the evaluation of the supply-chain performance in the healthcare sector.
As seen in this paragraph, the evaluation of supply chain relationships may be performed considering dyadic or network relationships, and focusing either on the supplier or on the buyer/customer perspective. The majority of studies focused on the customer (buyer) perspective for the evaluation of the relationship, because customer voice is deemed fundamental in order to improve the service quality provided. In particular, in inter-organizational contexts how to measure and use the customer voice is an issue both in public and private sector, since customer voice is considered as a proxy of the value created during the relational exchange between the two parties [10–11].
In this paper, a dyadic relationship between a supplier of medical products and a customer represented by the healthcare professionals that buy that products is investigated. A peculiarity of this study is that the relationship analyzed is a dyadic supply-chain relationship that belongs to the public sector sphere. In fact, in the public sector in general, and in the healthcare sector in particular, the majority of studies are focused on the evaluation of the relationship between a service provider (such as the health care professional) and the final customer (such as the patient), rather than on inter-organizational relationships. Also, in the public sector scholars mainly takes into consideration network relationships rather than dyadic ones [12–14].
This paper evaluates what occurs before the healthcare service is provided to the patient, in particular it investigates the provisioning service offered by a public organization to the healthcare professionals, from the perspective of the customer. More specifically, this work investigates the relationship between customer satisfaction, as perceived by the customer, and two of the main dimensions studied in relation to it, that are service quality and relationship quality. Moreover, the dyadic relationship is analyzed taking into consideration that different typologies of customers may evaluate differently the relationship with the supplier, since different customers have different needs and different expectations. Therefore, the analysis is conducted considering that the supplier establishes different relationships with different customers. This distinction also answers to the call [15–16] to consider contextual dimensions (such as the type of industry, the nature and intensity of the relationship, and the category of product or service under consideration), when analyzing the B-to-B relationships.
To conclude, this papers aims at understanding what determines customer satisfaction related to a provisioning public service and possible differences according to the customers’ typology. The provisioning service is provided by a public organization in the healthcare sector (i.e. the supplier), while the customers are healthcare professionals who directly or indirectly interact with the supplier. In particular, this article first analyzes whether or not service and relationship quality have a different impact on the overall customer satisfaction, also by taking into account the typology of customer. Finally, through a mediation model, the relationship between service quality, relationship quality and overall satisfaction with the supplier is investigated.
1.1 The supply chain in the Tuscan healthcare system
In this paper, the focus of analysis will be the relationship between the public organization that is in charge of the provisioning service in the healthcare system of the Tuscany region, and health professionals who relate with it. Since 2015, all the provisioning activities in the Tuscan healthcare system are carried out by a single organization, called Estar, that has its own independence on administrative affairs, legal personality, management and accounting. Estar represents a unique experience in the Italian panorama, since it is not only in charge of the purchasing activities, but it has also to guarantee an integrated supply chain in the Tuscan healthcare system . In addition to the provisioning activity, Estar is also responsible for the organization and fulfilment of the personnel recruitment and payment, public tendering, and information and communication technologies (ICT).
As regards the provisioning activity, Estar is in charge of the supply of several products, such as medical drugs, medical diagnostic devices, personal protection devices and administrative stuff and it became the unique supplier for all the healthcare authorities for the majority of products. Among the customers there are a plethora of different subjects (nurses, physicians, pharmacists, administrative staff, other health professionals, engineers, etc.), that can be divided in two groups: one composed by those subjects who have direct contacts with Estar, and the other one composed by those subjects who use the product provided by Estar, even if not interfacing directly with it. These two groups can be defined as the intermediaries and the end users, respectively. More specifically, intermediaries are direct customers since they are in charge of the product ordering, whereas the end users are indirect customers since they only use the products in their daily work activities. Therefore, end users do not relate with the supplier, rather with the intermediaries only. In the provisioning of the products, Estar has to guarantee not only service and product quality, but also support in managing the ordering procedure, in case the intermediator needs it. The latter aspect may be defined as the relational dimension, meaning that Estar has to be able to establish a good relationship with its customers, which entails being available when needed by the customer, and provide adequate answers to the customers’ requests.