@EnableTransactionManagement
public class JPAConfig {
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean localContainerEntityManagerFactoryBean =
                new LocalContainerEntityManagerFactoryBean();

        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        localContainerEntityManagerFactoryBean.setJpaVendorAdapter(vendorAdapter);

        DriverManagerDataSource driverManagerDataSource =
                new DriverManagerDataSource();
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("");
        driverManagerDataSource.setUrl("jdbc:mysql://localhost:3306/odontology");
        driverManagerDataSource.setDriverClassName("com.mysql.jdbc.Driver");

        localContainerEntityManagerFactoryBean.setDataSource(driverManagerDataSource);

        Properties properties = new Properties();
        properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect");
        properties.setProperty("hibernate.show_sql", "true");
        properties.setProperty("hibernate.hbm2ddl.auto", "update");
        localContainerEntityManagerFactoryBean.setJpaProperties(properties);
        localContainerEntityManagerFactoryBean.setPackagesToScan("org.odontology.models");

        return localContainerEntityManagerFactoryBean;
    }

    @Bean
    public JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory){
        return new JpaTransactionManager(entityManagerFactory);
    }
}

org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Could not open connection