Pivot root syndrome: the tip of a clinical iceberg

pivot root syndromeRory Mac Sweeney discusses pivot root syndrome, a novel pattern of bone degradation around canines, single-rooted molars, and certain roots on multi-rooted structures.

A novel pattern of bone degradation around canines, single-rooted molars, and certain roots on multi-rooted structures has been discovered. Specifically, the defects observed have formed around the individual roots of lower molars and the palatal roots of uppers, while both the opposite roots of the respective teeth remain intact. 

The diagnostic term ‘pivot root syndrome’ may be applied to these defects. In the absence of evidence to suggest that bacteria prefer such roots, an alternative explanation may be required. A recent narrative review reflects the prevailing consensus ‘that occlusal trauma and excessive occlusal forces do not initiate periodontitis or loss of connective tissue attachment’ (Fan and Caton, 2018). This subject, however, remains controversial.

The difficulties in formulating a firm position include differences in the study design, the body types used for investigation (including animal and/or human) and how the traumatic forces are applied (Hallmon, 1999). 

This article does not intend to retrace these arguments but to set the cat among the proverbial pigeons with a case study analysis of several teeth.  

Observations

Recently, the advent of CBCT scanning marked one of the biggest leaps in dental diagnostics, offering unprecedented visualisation of intrabony and furcation defects (Kasaj and Willershausen, 2007). 

Current concerns about CBCT imaging are focused primarily on radiation dosage. Consequently, it is advised that CBCT should only be employed if an affirmative diagnosis cannot be arrived at with lower dosage conventional imaging. 

However, the radiation dosage from CBCT has been observed to be equivalent to, or just slightly higher than, that from conventional imaging (Silva et al, 2008). Thus, we may have an inadvertent blind spot in our diagnostic field by missing out on the opportunities that CT scanning offers for defining bone pathology. 

A clinician and an assistant, operating in London, performed CT diagnoses daily between 2019 and 2021. They observed a series of periodontal defects. In all cases, the defects were discovered to be present in the absence of any other significant periodontal destruction. 

Any peripheral periodontal destruction can be contained within the extended paradigm defined by the clinical definition of pivot root syndrome.  

Pivot root

A pivot root is defined as a root upon which an abnormal amount of, and/or obtuse load force has been applied, resulting in a unilateral loss of the periodontal apparatus. Differential diagnoses include:

  • Localised periodontitis
  • Vertical root fracture
  • Perio-endo and endo-perio lesions. 

Pivot root is an inflammatory condition and frequently presents with both intraoral and extraoral swelling. Pocketing tends to be present; however, normal probing may be observed. Treatment is multidisciplinary, and the prognosis depends on the stage of intervention. 

It is proposed that the condition progresses through a series of three stages. The initial activity is proposed to occur in the cervical region of the periodontal ligament. In Figure 1 (stage one), we can see the ligament is inflamed on the mesial aspect of this lower molar. The tooth was being aggressively loaded on the distobuccal cusp in maximum intercuspation.  

A bone defect, it is proposed, will progress from the inflammatory activity in the ligament. This would be classified as a stage two lesion. 

The example in Figures 2 and 3 (stage two) shows a lower right first molar (female, aged 52). The distal root has a bone defect while the mesial root remains intact. The former is referred to as the pivot root (Figures 2 and 3). No pocket was evident.

A stage three lesion refers to when the condition has progressed to engulf the periapical apparatus. In Figures 4, 5 and 6 (stage three), we can see a plunger cusp has diminished the distal wall of the lower second molar.  

  • Figure 1: Stage one

Case presentations

Numerous case studies are presented, illustrated in Figures 7 to 28.  

  • Figures 7, 8, 9, 10, 11 and 12: Patient A (male, aged 46). Upper left first molar. The palatal root has total periodontal breakdown while the buccal roots remain intact (Figures 7 and 8). The lower right molar has partial loss of bone on the distal root while the mesial root remains undisturbed (Figures 9 and 10). The upper right canine has severe palatal bone loss (Figure 11). Palatal bone loss can be seen on both upper first molars as well as the canine (Figure 12)
  • Figures 13 and 14: Patient B (male, aged 48). Lower right first molar. The distal root exhibits severe tissue loss in the distal aspect. The mesial root remains unaffected (Figures 13 and 14). An abfraction lesion is noted. These are proposed to be associated with biomechanical stresses associated with normal chewing and swallowing (Grippo, 1991)
  • Figures 15, 16 and 17: Patient C (male, aged 52). Lower right first molar. The mesial root remains unaffected despite complete tissue loss around distal root. The upper right first molar exhibits significant bone loss (Figures 15 and 16). Both left canines exhibit severe bone loss with a distal bias (Figure 17)
  • Figures 18 and 19: Patient D (female, aged 62). Upper left first and second molars. Palatal roots exhibit complete bone deterioration: mesial roots remain undisturbed on the first molar; partial loss of tissue on the upper second, as an extension of the tissue loss from the palatal ridge
  • Figures 20 and 21: Patient E (female, aged 52). Lower left molar. The mesial root remains vital and unaffected despite complete loss of structure around the distal root
  • Figures 22 and 23: Patient F (male, aged 54). Lower left second molar. Partial loss of the mesial apparatus as an extension of the total consumption of the distal periodontium. The tooth was vital
  • Figures 24 and 25: Patient G (female, aged 52). Upper right first molar. The palatal root has severe periodontal tissue loss while buccal roots remain unaffected

Conclusion 

Pivot root syndrome is a new diagnostic term that describes vertical periodontal defects that have a distinctive unilateral pattern. 

You should view local periodontal defects in 3D to avoid diagnostic errors with the differential diagnosis. 

It is not considered a coincidence that the teeth involved in mastication (including canine and/or group function) are the foci of the pattern. It is speculated that the underlying cause may be of an orthopaedic nature. Further dentoskeletal analysis is required.      

  • Figures 26, 27 and 28: Patient H (female, aged 30). Lower left second molar. The single root (Figure 26) shows a lingual bias in the bone loss pattern (Figure 27). The bone loss pattern follows the contour of the morphology of the root

This article first appeared in Clinical Dentistry magazine. To read more articles like this you can sign up to the magazine here.

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