TOOTH POSITION–RELATED CONDITIONS
Tooth crowding, crossbite, extreme overjet/overbite, and malposition are very common forms of malocclusion235,236 and often associated with worsened periodontal conditions.237–239 Studies evaluating the prevalence of crowding and periodontal diseases had reported values ranging between 58% and 95%, and their presence is seemingly influenced by age.240–243
Different definitions and grading scores have been proposed to assess crowding for periodontal purposes.226,244,245 Van Kirk developed a scoring index to examine malalignment.244 Score 0 was given to an ideal alignment with no deviation from the ideal arch line projected through contact areas. Minor and major malalignment conditions were also assessed by the degree of rotation and displacement. Score 1 includes situations where rotation is less then 45 degrees and malalignment less 1.5 mm. Score 2 includes situations of rotation exceeding 45 degrees and displacement equal to or more than 1.5 mm.
To date, it remains controversial whether tooth position–related factors exert a significant impact on the periodontium using oral hygiene as a confounding factor.226,246–255 Early studies showed a correlation between crowding and increased loss of clinical attachment, plaque accumulation, and gingival inflammation.241,256–258 On the other hand, other studies reported that crowding has no effect on periodontal health.226,235,240,259–261
Results from a cross-sectional study among 154 army recruits concluded that tooth malposition does not enhance periodontal breakdown; however, it decreases the ability for optimal oral hygiene habits.242 Ultimately, Ingervall et al demonstrated that crowding did not favor plaque accumulation or extent of gingival inflammation in an experimental gingivitis model.245
Because tooth crowding is not a causal agent for the initiation of periodontal disease, it must be considered in conjunction with biofilm as a contributing factor for periodontal breakdown.262 Hence, individuals with poor plaque control and crowding might be more susceptible to attachment loss.
IMPACTED THIRD MOLARS
Generally, third molar sites are prone to plaque accumulation due to the difficulty of proper access for oral hygiene. Also, impaction of these teeth might create vertical defects on the distal surfaces of second molars.
In a retrospective study, Kugelberg showed a significant correlation between bone healing of third molar extraction sites and patient age.263 Residual probing depths greater than 7 mm and intrabony defects exceeding 4 mm in depth were evaluated in the distal surfaces of second molars after extraction of impacted mandibular third molars. Curiously, a significant improvement of the intrabony defect depth was noted among individuals under 25 years old (Table 5-14).263
TABLE 5-14 Incidence of residual intrabony defects after third molar extraction263
PD, probing depth.
Later, Kugelberg et al confirmed their previous findings in a prospective study and provided evidence that periodontal healing after third molar extraction is impaired in patients over 30 years.264 One year postoperatively, 14% of patients aged 20 years or younger had residual intrabony defects of 4 mm or greater, while 47% of the patients aged 30 years or older had intrabony defects 4 mm or greater following removal of the impacted third molars. Thus, early removal of the impacted third molars with severe angulation and close positional relationship adjacent to the second molars will benefit the periodontal health.264
RETENTION OF HOPELESS TEETH
Several studies have investigated the potential detrimental effects of retention of a hopeless tooth. In a retrospective study with a 4-year observation period, Machtei et al defined teeth as hopeless when Class III furcation involvement or more than 50% alveolar bone loss was present.265 It was later demonstrated that in the absence of periodontal therapy, an annual bone loss at dentition adjacent to hopeless teeth was 10 times greater (3.12% vs 0.23%) than the teeth adjacent to the healed sockets of extracted hopeless teeth. Conversely, DeVore et al and Wojcik et al presented data of 17 hopeless teeth with a mean follow-up of 3.41 years266 and 8.4 years,267 suggesting that retention of hopeless teeth has no effect on the proximal periodontium prior to and following periodontal therapy.
Overall, these studies demonstrated that the effect of the retention of hopeless teeth on adjacent dentition is diminished as long as active and supportive periodontal therapy is provided. Hence, Machtei revisited his previous findings and concluded that the long-term preservation of these teeth following periodontal surgery is feasible with no detrimental effects on the adjacent proximal teeth268 (Box 5-4).265–268
BOX 5-4 Effect of retained hopeless teeth upon the adjacent periodontium
| Negative effect (absence of periodontal therapy)– Machtei et al265No effect (with periodontal therapy)– DeVore et al266– Wojcik et al267– Machtei and Hirsch268 |
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