<div>
  <span class="itemNavigationTitle">Im Konvolut blättern:</span>

  <button md-button title="vorangehender Text" *ngIf="idOfPrev"
          [routerLink]="[idOfPrev]" (click)="goToPrevFassung()" >
    <md-icon>navigate_before</md-icon>
    {{ titleOfPrev }}
  </button>

  <button md-button title="nächster Text" *ngIf="idOfNext"
          [routerLink]="[idOfNext]" (click)="goToNextFassung()">
    <md-icon>navigate_next</md-icon>
    {{ titleOfNext }}
  </button>
</div>

<div>
  <span class="itemNavigationTitle">Im Konvolut blättern:</span>

  <button md-button title="vorangehender Text" *ngIf="idOfPrev"
          [routerLink]="[idOfPrev]" (click)="goToPrevFassung()" >
    <md-icon>navigate_before</md-icon>
    {{ titleOfPrev }}
  </button>

  <button md-button title="nächster Text" *ngIf="idOfNext"
          [routerLink]="[idOfNext]" (click)="goToNextFassung()">
    {{ titleOfNext }}
    <md-icon>navigate_next</md-icon>
  </button>
</div>

Move navigate_next icon after the poem title
Move navigate_next icon after the poem title
