Apical Shift Research Articles

Periodontal conditions in adult patients with cleft lip, alveolus, and palate.

The present study assessed the progression rate of periodontal disease over 8 years in a group of 52 adult patients with various forms of cleft lip, alveolus, and palate considered at risk for progression of periodontal disease. Of special interest was the evaluation of periodontal disease progression at sites adjacent to cleft regions compared to changes found at control sites not directly affected by such defects. High incidences of generalized plaque accumulation and bleeding on probing were noted at both examinations in 1979 and 1987. A mean apical shift of the clinical attachment level amounting to 0.2 mm had occurred over the 8-year observation period. A slight apical displacement of the mesial and distal mean crestal alveolar bone was also noted. The rate of progression of periodontal disease over the 8 years was not found to be different at statistically significant levels at cleft sites compared to control sites. However, the results of this study documented that the cumulative periodontal destruction at 26 to 28 years of age was statistically significant and more pronounced at cleft sites as revealed by greater probing pocket depth and loss of clinical attachment. The differences between test and control sites amounted to 0.3 and 0.4 mm respectively for probing depth and 0.6 mm for loss of clinical attachment. In addition, the discrepancy between alveolar bone height and the levels of the clinical attachment at cleft sites demonstrated the presence of a long supracrestal connective tissue attachment adjacent to cleft defects. Therefore, the alveolar bone height as visualized in radiographs at such sites was considered an unreliable diagnostic tool for the assessment of the degree of periodontal destruction.

Periodontal Conditions in Adult Patients with Cleft Lip, Alveolus, and Palate

The present study assessed the progression rate of periodontal disease over 8 years in a group of 52 adult patients with various forms of cleft lip, alveolus, and palate considered at risk for progression of periodontal disease. Of special interest was the evaluation of periodontal disease progression at sites adjacent to cleft regions compared to changes found at control sites not directly affected by such defects. High incidences of generalized plaque accumulation and bleeding on probing were noted at both examinations in 1979 and 1987. A mean apical shift of the clinical attachment level amounting to 0.2 mm had occurred over the 8-year observation period. A slight apical displacement of the mesial and distal mean crestal alveolar bone was also noted. The rate of progression of periodontal disease over the 8 years was not found to be different at statistically significant levels at cleft sites compared to control sites. However, the results of this study documented that the cumulative periodontal destruction at 26 to 28 years of age was statistically significant and more pronounced at cleft sites as revealed by greater probing pocket depth and loss of clinical attachment. The differences between test and control sites amounted to 0.3 and 0.4 mm respectively for probing depth and 0.6 mm for loss of clinical attachment. In addition, the discrepancy between alveolar bone height and the levels of the clinical attachment at cleft sites demonstrated the presence of a long supracrestal connective tissue attachment adjacent to cleft defects. Therefore, the alveolar bone height as visualized in radiographs at such sites was considered an unreliable diagnostic tool for the assessment of the degree of periodontal destruction.

Location of the mucogingival junction 18 years after apically repositioned flap surgery

The apically repositioned flap procedure, by definition, implies that the mucogingival junction (MGJ) is shifted into an apical location. That this actually would be the case has never been shown in long-term studies. The 13 subjects in the present study had during the years 1964-1965 received treatment of moderately advanced periodontal disease (probing pocket depths less than or equal to 5 mm) in the lower jaw. An apically repositioned flap (ARF) procedure was applied in the left or right half of the mandible and a gingivectomy (GE) was performed in the contralateral side. Starting in December 1981, the patients were recalled for clinical and radiographic determination of long-term results. The width of the band of keratinized gingiva was measured clinically and the distance from the MGJ to the lower border of the mandible (LBM) was measured from orthopantomograms. Slightly less keratinized gingiva was observed on the sides where GE had been used. There was no statistically significant difference in the orthopantomographic distance from the MGJ to the LBM between ARF and GE operations. The results indicate that the apically repositioned flap procedure does not result in a permanent apical shift of the MGJ.

歯肉炎症の拡がりに対する付着歯肉の役割に関する実験的研究

The purpose of this study was to evaluate the inflammatory response in dento-gingival units with or without attached gingiva in monkeys. Two different types of dento-gingival units with or without attached gingiva were established in premolar and first molar areas of three monkeys. In the experimental group, a part of the keratinized gingiva was removed with periodontal scissors following mucoperiosteal flap procedure, while in the control group, sham surgery was performed. After the surgery, plaque control was performed by mechanical tooth cleaning procedures three times a week for 3 months. As baseline examinations, width of the keratinized gingiva, probing pocket depth, position of the gingival margin, and the clinical attachment level were recorded and oral photographs were taken. Following these examinations silk ligatures were placed around the neck of the teeth to induce gingival inflammation in both the experimental and control groups. A soft diet which allowed plaque accumulation on the teeth was given during the experimental periods. The clinical examinations were carried out at 0, 1, 2, 3, 5 and 12 weeks and all monkeys were sacrificed for histological examination. The results obtained were as follows: 1. The use of silk ligature and a soft diet produced moderate to severe gingival inflammation in the monkeys. 2. The degree of gingival inflammation was greater in the experimental group which was characterized by the absence of the attached gingiva. 3. Marked marginal tissue recession with an apical shift of the attachment level was found in the gingival units of the experimental group at 12 weeks. 4. Histologically, a distance between the level of notch on the root surface and the most apical position of epithelial cell was greater in the experimental groups at 5 and 12 weeks, compared with the pre-experimental level. 5. The degree of alveolar bone resorption was higher in the experimental group at 5 and 12 weeks. These results suggest that an attached gingival tissue plays a certain role as a barrier against the extension of gingival inflammation.

Location of the centers of resistance for anterior teeth during retraction using the laser reflection technique

The location of the centers of resistance for various symmetric units of the anterior maxillary dentition for a lingually directed force was studied in two dry human skulls. The units investigated were composed of (1) two incisors, (2) four incisors, and (3) six anterior teeth. In addition, the effect, of change in force magnitude on the location of the centers of resistance of these units was investigated. The laser reflection technique was used to study both the direction and magnitude of the initial displacement of the consolidated Teeth under loading. The results indicated that the center of resistance shifted apically with the incorporation of a greater number of teeth into an anterior segment. With a unit of six anterior teeth, the apical shift of the center of resistance was the greatest. Increasing force levels had little effect on the location of the center of resistance of a given unit. This phenomenon was observed in both the skulls tested, suggesting that general trends may exist in the displacement characteristics of the dentition when subject to controlled force systems.

Frequency-specific effects of stimulus rise-fall time on the human BAEP

High-pass masking was used to determine the effect of varying rise-fall time (0, 1, 2, and 5 ms) on the frequency specificity of the brainstem auditory evoked potential (BAEP) to 50 dB nHL noise bursts. The latencies and amplitudes of frequency-specific waveforms were obtained by subtractive masking [Don and Eggermont, J. Acoust, Soc. Am. 63, 1084–1092 (1978)]. Results showed increasing latency and decreasing amplitude of wave V with decreasing frequency band. Increasing rise-fall time within a frequency band prolonged latencies and decreased amplitudes. There was a convergence of latency values between rise-fall times as frequency band decreased consistent with a place mechanism. However, divergent latency differences between rise-fall times but within frequency bands suggests that additional mechanisms may be operative. Amplitude effects were complex but there was a suggestion that increasing rise-fall time results in an apical shift in the generation of the BAEP. Traveling-wave velocities calculated using previously published techniques and the latencies described herein are in good agreement with prior estimates in the human. [Work supported by NIH.]

The effect of orthodontic tilting movements on the periodontal tissues of infected and non‐infected dentitions in dogs

Abstract The aim of the present investigation was to study (1) whether it was possible, by orthodontic tooth movement, to shift a supragingivally located plaque into a subgingival position, and (2) periodontal tissue reactions around tilted and intruded plaque‐infected teeth.The experiments were performed on five dogs which were fed a diet that allowed dental plaque accumulation. The lower third premolars (3P and P3) were extracted and a phase of experimental periodontal breakdown was initiated on day 0. The periodontal pockets around the lower fourth premolars (4P and P4) were eliminated on day 210. During surgery, a notch was prepared in the root at the level of the marginal alveolar bone in order to facilitate measurements in radiographs and histological sections. After 60 days of healing with plaque control, i.e. on day 270, orthodontic appliances producing tipping forces on 4p and P4 were inserted. From day 270 to day 450, plaque was allowed to accumulate on 4P (test = T) while P4 (control = C) was brushed twice daily. The dogs were sacrificed on day 450. Following sacrifice, tissue sections comprising 4P, 1M and P4, M1 were produced and subjected to microscopic analysis.The present investigation showed that it was possible by orthodontic tooth movement to shift a supragingivally located plaque into a subgingival position. The mesial‐apical movement of the plaque‐infected teeth resulted in the formation of infrabony pockets. In four out of five dogs the displacement of the plaque‐infected tooth resulted in an apical shift of the connective tissue attachment. When similar orthodontic forces were acting on plaque‐free teeth, the tilting movement did not result in the formation of infrabony pockets. In only two dogs did the treatment result in loss of connective tissue attachment.

ブラッシング方法の差による炎症歯肉辺縁の根尖側移動の程度について

The purpose of this study was to compare the degree of apical shift of gingival margin on inflamed gingiva by three toothbrushing techniques (modified Stillman's, roll and scrubbing method). Fifty-seven patients with mild periodontitis were used for this study. Patients were divied to three groups (19 patients for each group). Each group was instructed one of the three methods, at the beginning of the study. The position of the gingival margin was assessed on labial surface of upper and lower central incisors. At the same time, pocket depth of the labial and proximal surfaces as well as gingival and plaque index was scored. These examinations were performed at the beginning of the study, and were repeated at the 1st, 3rd, 5th, 9th and 13th week.The results of this examination were as follows.At the labial area, apical shift of gingival margin was found in all three groups. The modified Stillman's method showed the highest tendency to reduce the position of margin. Then the rolling method was followed. The scrubbing method made a minimum change on gingival margin. The bottom of the pocket, however, did not change during the period of this study in spite of difference of three brushing meshods.At the proximal areas, period of this the scrubbing method was found to significantly reduce the pocket depth when compared with other methods.The scrubbing method was the most effective on plaque removal among three brushing methods.Gingival Index scores were decreased during the period of this study, though significant differences among the three methods could not be found.