Fernando Suarez - Periodontics

Tooth crowding, crossbite, extreme overjet/overbite, and malposition are very common forms of malocclusion 235,236and often associated with worsened periodontal conditions. 237–239Studies 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. 226,244,245Van Kirk developed a scoring index to examine malalignment. 244Score 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. 226,246–255Early studies showed a correlation between crowding and increased loss of clinical attachment, plaque accumulation, and gingival inflammation. 241,256–258On 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. 242Ultimately, 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. 262Hence, individuals with poor plaque control and crowding might be more susceptible to attachment loss.

Generally, third molar sites are prone to plaque accumulation due to the difficulty of proper access for oral hygiene. Also, impactionof 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. 263Residual 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 extraction 263

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. 264One 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

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. 265It 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 years 266and 8.4 years, 267suggesting 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 teeth 268( Box 5-4). 265–268

BOX 5-4 Effect of retained hopeless teeth upon the adjacent periodontium

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